Download Apraxia continued - Huntington`s Disease Support Information

I started the accumulating these definition which are sometimes used to describe symptoms of/or
tests for HD or discuss other diseases or condition which have symptoms similar to Huntington's
Disease. The majority of information comes from the Physician’s Guide to HD or other online
medical links describing neurological or motor disorders.This list is very long, but interesting so
get a cup of coffee and prepare to sit a spell!
Jean
Color Coding of Words
Symptoms
Scientific/Technical
Testing
Drug
Other diseases similiar to HD
Action tremor: a tremor that occurs during the
performance of voluntary movements. Such
tremors include postural, isometric, kinetic, and
intention tremors.
Activities of daily living (ADL):
functions that are typically performed as part of
a person's daily routine, such as dressing,
bathing, eating, toileting, leisure activities,
socialization, and other functions of daily
living. (see HD Activities of Daily Living)
Acute:
Referring to symptoms of abrupt onset, often of
marked severity or intensity.
AEP/BAER:
Auditory-evoked potentials, or "brainstem
auditory-evoked response") are the responses
of the brainstem and auditory regions of the
cortex to brief sounds in the ear. In addition to
determining abnormalities of hearing, AEPs
may be helpful in finding subtle problems with
the function of the brainstem.
Akathisia (restlessness)
Is an extremely uncomfortable internal sense of
restlessness, sometimes induced by
neuroleptics, which may cause patients to pace,
or be unable to sit still. It can be mistaken for
agitation or anxiety, prompting the physician to
increase the dose of the offending drug,
creating a vicious cycle.
Akinesia:
absence of movement or loss of the ability to move
such as temporary or prolonged paralysis or
"freezing in place."
Akinetic:
Referring to absence or poverty of voluntary
movement; loss of the ability to move all or part
of the body
Alpha 2-adrenergic agonist:
A drug that reduces the activity of the
neurotransmitter norepinephrine by
stimulating certain receptors within the central
nervous system (central presynaptic alpha 2adrenergic receptors). The release of
norepinephrine triggers action within the
sympathetic nervous system. This part of the
nervous system regulates certain involuntary
activities during stress, such as increasing the
heart rate, deepening breathing, and raising
blood pressure. Norepinephrine also plays a
role in regulating mood and emotion. The
administration of alpha 2-adrenergic agonists
may result in a reduced heart rate and lowered
blood pressure and have depressive or sedative
effects.
Ambulant (ambulatory):
Able to walk; may be used to describe patients
who do not require a wheelchair or are not
confined to bed.
Ambulation: The act of walking
Amino acid:
The chemical "building blocks" or basic
structural units of proteins. All proteins in the
body are formed from a "pool" of 20 different
amino acids. Some are essential
amino acids and must be supplied by the diet.
The remainder are classified as "nonessential."
These can be made by the body and need not
come from the diet.
Amniocentesis: (prenatal test)
A screening or diagnostic procedure during
which a sample of amniotic fluid surrounding
the developing fetus is withdrawn by means of
an ultrasound-guided needle. The amniotic sac
is a fluid-filled membrane that surrounds and
protects the developing fetus within the uterus.
Amniotic fluid contains cells that may be used
for DNA analysis, chromosomal testing, and
enzyme studies. Such testing may detect certain
genetic disorders, metabolic diseases,
chromosomal abnormalities, or developmental
defects. This procedure is typically performed
between the 14th and 18th week of pregnancy.
Amplitude:
The "size" or "height" of a tremor; the extend or
breadth of a tremor's range.
Anhedonia
Lack of interest in acts that previously provided
pleasure
Angiography:
During this test, a series of regular x-rays are
taken as a radiopaque (impenetrable by x-ray)
contrast material (dye) is injected directly into
an artery. The resulting radiographic image is
like a map of the blood vessels. An angiogram
is an accurate way of looking at arteries and
veins of the head, neck and brain, and provides
information that cannot be obtained with other
tests. It is often used to determine the degree of
narrowing of an artery in the head or neck.
Angiography: continued
It can also be used to detect the location and
size of aneurysms and vascular malformations.
This is an invasive test, requiring a physician to
insert a catheter into the major artery near the
groin and direct it "upstream" to the arteries
near the brain.
Antagonist:
(1) A drug that blocks a receptor,preventing
stimulation.
(2) A muscle whose contraction opposes an
intended movement.
Antibodies:
Specialized proteins that function as an
essential part of the immune system.
Antibodies are produced by certain white blood
cells (B cells) in response to the
presence of specific, usually foreign proteins
(i.e., antigens), helping the body to neutralize
and destroy the invading microorganism,
foreign tissue cell, or
other antigen in question.
Anticholinergics:
Drugs that block the action of acetylcholine, a
neurotransmitter whose effects oppose
dopamine. By blocking acetylcholine's action,
these drugs increase dopamine's ability to
control movement.
Anticholinesterase:
An agent that inhibits action of acetylcholinesterase (AChE). AChE is an enzyme that
inactivates acetylcholine, a neurotransmitter at
the junctions of nerve and muscle cells
(neuromuscular junctions) that regulates the
delivery of messages from neurons to muscle
fibers. By inhibiting the activity of AChE, such
medications allow high levels of acetylcholine
to accumulate, potentially enabling repeated
stimulation of nerves at neuromuscular
junctions.
Anticonvulsant medication:
An agent that prevents or arrests convulsive
seizures.
Antioxidants:
Agents that inhibit or neutralize potentially
harmful compounds known as free radicals.
Free radicals are produced during metabolic
activity. High levels of free
radicals may eventually lead to impaired
functioning and destruction of neurons and
other bodily cells. Certain antioxidants are
thought to neutralize free radicals before
cellular damage occurs.
Anxiety -is a word that can be used to mean the
same thing are worry, stress, or nervousness. In
psychology-speak, anxiety is seen as a feeling
that a person has when they think there is some
sort of threat or danger to them. Anxiety is
usually split into two different types; Panic
Attacks, and Generalised Anxiety States which
you can think of as people who worry too much
about everything. Physical signs of Generalised
anxiety can include Shakiness, Tensed up
muscles, Sweating, Palpitations, Dry mouth,
Finding it hard to concentrate and Going to the
toilet a lot. Some of the most effective forms of
therapy for this problem include CognitiveBehavioural Therapy, Behavioural Therapy,
and various techniques such as Relaxation.
Various drugs can also be used, and there are
now specialist treatment packages available
specifically designed to help manage anxiety.
Aphasia: (Language/speech)
Loss or impairment of language comprehension
or production is calledaphasia. The difficulties
in language function must not be attributable to
impairment of the speech or writing production
apparatus, such as muscles ofthe tongue and
throat, or peripheral sensory loss. Although the
personsuffering such impairment may have
trouble articulating a languageutterance, the
brain centers moderating language are
presumably intact.
Apoptosis:
Cell death due to a programmed pattern of
gene expression; a form of cell death in which
certain enzymes activate to degrade DNA
within the nucleus, resulting in cellular
degeneration and loss.
Apraxia:
Apraxia is a collective term used to describe
impairment in carrying out purposeful
movements. Loss of the ability to sequence,
coordinate, and execute certain purposeful
movements and gestures in the absence of
motor weakness, paralysis, or sensory
impairments. Apraxia is thought to result from
damage to the cerebral cortex, such as due to
stroke, brain tumors, head injury, or infection.
It may also occur as a result of impaired
development of the cortex as in certain
neurodevelopmental disorders, including Rett
syndrome.
Apraxia may affect almost any voluntary
movements, including those required for
proper eye gaze, walking, speaking, or writing.
Impaired or absent language function, usually
referring to speech; which results from an
injury to brain structures usually in the
dominant hemisphere (the side of the brain that
controls language function is usually the side
opposite to the handedness of the person and is
referred to as the dominant hemisphere by
definition).
People with severe aphasia are usually
extremely limited in explaining themselves by
pantomime or gesture, except for expressions of
emotion. Commonly they will show you
something in their wallet, or lead you to show
you something, but this is the extent of their
non-verbal communication.
Specific examination usually shows that they
are unable to perform common expressive
gestures on request, such as waving good-bye,
beckoning, or saluting, or to pantomime
drinking, brushing teeth, etc. (limb apraxia).
Apraxia continued
Apraxia may also primarily affect oral, nonspeech movements, like pretending to cough or
blow out a candle (facial apraxia).
This disorder may even extend to the inability
to manipulate real objects. More often,
however, apraxia is not very apparent unless
one asks the patient to perform or imitate a
pretended action. For this reason it is almost
never presented as a complaint by the patient
or the family. Nevertheless it may underlie the
very limited ability of people with aphasia to
compensate for the speech impairment by using
informative gestures.
Aphasia-Anomic
This term is applied to persons who are left
with a persistent inability to supply the words
for the very things they want to talk aboutparticularly the significant nouns and verbs. As
a result their speech, while fluent in
grammatical form and output is full of vague
circumlocutions and expressions of frustration.
They understand speech well, and in most
cases, read adequately. Difficulty finding words
is as evident in writing as in speech.
Apraxia of speech
This term is frequently used by speech
pathologists to designate an impairment in the
voluntary production of articulation and
prosody (the rhythm and timing) of speech. It is
characterized by highly inconsistent errors.
This web site provides
information on ocular motor apraxia including
message boards and mailing lists.
http://wwweb.org/oma/
Apraxia-Ocular Motor
Ocular Motor Apraxia (OMA) is a visual
condition where a child or person has difficulty
in controlling their horizontal eye movements.
This web site provides information on ocular
motor apraxia including message boards and
mailing lists.
http://wwweb.org/oma/
Aphasia--Mixed non-fluent
This term is applied to patients who have
sparse and effortful speech, resembling severe
Broca's aphasia. However, unlike persons with
Broca's aphasia, they remain limited in their
comprehension of speech and do not read or
write beyond an elementary level.
Aphasia-Wernicke's
In this form of aphasia the ability to grasp the
meaning of spoken words is chiefly impaired,
while the ease of producing connected speech is
not much affected. Therefore Wernicke's
aphasia is referred to as a 'fluent aphasia.'
However, speech is far from normal.Sentences
do not hang together and irrelevant words
intrude-sometimes to the point of jargon, in
severe cases. Reading and writing are often
severely impaired.
Aphasia--Other varieties
In addition to the foregoing syndromes that are
seen repeatedly by speech clinicians, there are
many other possible combinations of deficits
that do not exactly fit into these categories.
Some of the components of a complex aphasia
syndrome may also occur in isolation. This may
be the case for disorders of reading (alexia) or
disorders affecting both reading and writing
(alexia and agraphia), following a stroke.
Severe impairments of calculation often
accompany aphasia, yet in some instances
patients retain excellent calculation in spite of
the loss of language.
Apraxia - Links:
Links: Developmental Coordination Disorder
(DCD) Also called "limb apraxia,"
"global apraxia," or "developmental dyspraxia".
and Motor Disorders of Speech and the
PROMPT System (click on titles to go there)
Antipsychotic describes the category of drug
whose original or most common use and
intended therapeutic effect is to control or
prevent psychiatric symptoms of psychosis or
to treat mental disorders whose features
include psychotic symptoms such as
hallucinations and delusions
Archimedes spirals:
a relatively simple test used to evaluate tremor
severity. During this test, the patient is asked to
draw increasingly wider circles on a piece of
paper.
Asterixis: involuntary, jerking or flapping
movements, especially of the hands. Extending
the patient's arm with the wrist bend in a
backward position may induce this form of
tremor, which may be associated with
advanced liver disease
Astrocyte:
A type of glial cell. Glial cells are the connective
tissue cells of the central nervous system (CNS),
serving as the supportive structure that holds
together and protects neurons.
Ataxia:
A condition characterized by an impaired
ability to coordinate voluntary movements.
Ataxia may result from damage to the
cerebellum, cerebellar pathways, or the spinal
cord due to various underlying disorders,
conditions, or other factors. The condition is
often characterized by incoordination, postural
imbalance, and a lurching, unsteady manner of
walking (gait). Additional findings may include
slurred speech (dysarthria); rapid, involuntary,
rhythmic eye movements (nystagmus); and/or
other abnormalities.
Athetosis:
Involuntary, relatively slow, writhing
movements that essentially flow into one
another. Athetosis is often associated with
chorea, a related condition characterized by
involuntary, rapid, irregular, jerky movements.
Although athetosis may be most prominent in
the face, neck, tongue, and hands, the condition
may affect any muscle group. Athetosis may
occur in association with certain neurodegenerative diseases, such as Huntington's or
Wilson's disease, or cerebral palsy (CP). It may
also result from infections affecting the brain or
the use of particular medications.
Atrophy:
Wasting away or loss of a cell, tissue, or organ
due to disease, malnutrition, insufficient blood
supply, or other causes, such as loss of skeletal
muscle mass
due to peripheral nerve damage.
Atypical:
Irregular; not standard or characteristic; not
conforming to type.
Autoimmune: Referring to an immune
response against one's own tissues or organs.
Autoimmune diseases result from abnormal
immune reactions in which the actions of
certain white blood cells (T cells) are directed
against "self proteins" (autoantigens) or normal
tissue components (i.e., cell-mediated immune
response)--or in which specialized proteins
(antibodies) produced in response to specific,
usually foreign proteins (antigens) improperly
act against certain of the body's own cells (i.e.,
antibody-mediated immune response). In
certain disorders, the autoimmune process may
be primarily directed against one organ, such as
the thyroid gland in Hashimoto's thyroiditis or
the pancreas in insulin-dependent diabetes
mellitus, or may involve multiple organs and
bodily systems, such as associated with
systemic lupus erythematosus (lupus or SLE).
Autosomal dominant trait:
Human traits, including an individual's eye
color, hair color, or expression of certain
diseases, result from the interaction of one gene
inherited from the father and one gene from the
mother. In autosomal dominant disorders, the
presence of a single copy of a mutated gene
may result in the disease. In other words, the
mutated gene may dominate or "override" the
instructions of the normal gene on the other
chromosome, potentially leading to disease
expression. Individuals with an autosomal
dominant disease trait have a 50 percent risk of
transmitting the mutated gene to their children.
Autosomal recessive trait:
Human traits, including an individual's hair
color, specific blood group, or expression of
certain diseases, result from the interaction of
one gene inherited from the mother and one
from the father. With autosomal recessive
disorders, two copies of the disease gene must
be inherited in order for an individual to
potentially develop the disease. If both the
mother and father carry a copy of the disease
gene, each child has a 25 percent risk of
inheriting the two genes for the disease.
There is a 50 percent risk that their children
may inherit one copy of the disease gene and be
carriers for the disease trait (heterozygous
carriers). In addition, there is a 25 percent
chance that the parents' offspring will inherit
two normal copies of the gene and will not
develop the disorder nor be carriers for this
disease trait.
Aura:
Syptoms that occur prior to a particular
neurological ATAXIA: Un-coordination;
Inability to coordinate the muscles in voluntary
movement.
Athetosis and Ballismus:
are opposite ends of the spectrum of chorea,
ballismus consisting of a violent flinging
movement. Athetosis is a slow, worm-like
writhing movement of the limbs, trunk, head,
face or tongue. These two disorders have
different neuropathologic substrates; however,
they seldom occur in pure form.
When athetosis merges with chorea, it is called
choreoathetosis; when merged with dystonia it
is athetotic dystonia. Athetosis and ballisumus
respond to drugs similarly (tetrabenazine)
depletes dopamine], clonazepam or valproate.
Problems (such as seizure or migraine) that
serve as a warning that the abnormal spell may
follow. Includes disturbances in vision, smell or
perception.
Autoimmune:
An abnormal response of the immune system,
causing antibodies and immune mediated cells
to attack parts of the body. This mechanism
may explain many diseases.
Autosomal dominant trait:
Human traits, including an individual's eye
color, hair color, or expression of certain
diseases, result from the interaction of one gene
inherited from the father and one gene from the
mother. In autosomal dominant disorders, the
presence of a single copy of a mutated gene
may result in the disease. In
other words, the mutated gene may dominate
or "override" the instructions of the normal
gene on the other chromosome, potentially
leading to disease expression. Individuals with
an autosomal dominant disease trait have a 50
percent risk of transmitting the mutated gene to
their children.
Axon:
The inner core of peripheral nerves. Axons are
the relatively slender extensions of neurons that
transmit nerve impulses away from nerve cell
bodies. The ends of the axons or "terminals"
release chemical substances known as
neurotransmitters, enabling the transmission of
nerve impulses to other neurons or effector
organs.
Baclofen:
A mainstay of antispastic drug therapy,
baclofen is a GABA agonist that stimulates the
GABAB autoreceptor. When stimulated, this
autoreceptor inhibits muscle activity. In
experimental systems, baclofen inhibits the
release of noradrenaline, and acetylcholine
from peripheral nerve endings, and
acetylcholine, noradrenaline, dopamine,
serotonin, and glutamate from CNS neurons.
BAER (brainstem auditory evoked
response):Measures function of Central
Nervous System, including pathway from
brainstem
Ballismus: An abnormal neuromuscular
condition that is generally considered a severe
form of chorea. Involvement of the upper
muscles of the arms and legs results in
uncontrolled, violent, flinging or throwing
actions. These swinging or jerky movements
may be sporadic or continuous and, in some
patients, restricted to one side of the body
(hemiballismus). Ballismus often occurs in
association with other abnormal involuntary
movements, including athetosis, chorea, and
dystonia.
Basal ganglia:
A series of structures located deep in the brain
responsible for initiating and regulating motor
movements. Specialized nerve cell clusters of
gray matter deep within each cerebral
hemisphere and the upper brainstem, including
the striate body (caudate and lentiform nuclei)
Basal ganglia: continued
and other cells groups such as the subthalamic
nucleus and substantia nigra. The purpose for
the basal ganglia is not known, but much is
known about the types of symptoms that occur
when they are damaged. One recent theory
suggests that a purpose of the basal ganglia is
to select and accentuate certain motor patterns
while inhibiting other "nearby" patterns. Once
the pattern is selected by the basal ganglia, it is
then fed back onto the motor cortex and
amplified in order to begin movement. At the
same time, all other possible patterns are
inhibited in order that only the desired pattern
becomes active. This system must be very
finely tuned. When it is damaged, there may be
errors in the selected pattern, excessive
feedback that may cause oscillations, or
insufficient feedback to initiate rapid
movement.
Benzodiazepines: A class of medications that
act upon the central nervous system to reduce
communication between certain neurons,
lowering the level of activity in the brain.
Benzodiazepines are effective in reducing
anxiety, stress, or agitation; promoting sleep;
alleviating restlessness; and relaxing muscles.
Beta-adrenergic receptor: A specialized
molecular structure on the surface membrane
of a neuron that selectively receives the
neurotransmitter norepinephrine. Reception of
this neurotransmitter causes changes in the
neuron that increase its likelihood of "firing" or
sending its own signal to other neurons. The
activities of norepinephrine affect that part of
the nervous system involved in the control of
some involuntary body functions, such as blood
pressure regulation, etc. (sympathetic nervous
system).
Biopsy of brain-is used only in the most severe
cases and is performed in the operating room
by a neurosurgeon. The skull must be opened
and several days are usually required for
recovery.
Biopsy of Muscle-is performed in the
operating room. This is a relatively simple
procedure and the person can usually go home
the same day. The incision leaves a small scar
over the area where the muscle or nerve is
removed.
Biopsy of nerve-a relatively unimportant nerve
is chosen to minimize the effect for the
procedure. For muscle biopsy, only a small
piece of tissue is taken so there is no effect on
strength. For certain tests, the muscle must be
immediately analyzed or flash-frozen for
transport to a specialized laboratory.
Biopsy of skin-is a rapid procedure during
which a small circular knife is used to extract a
2 to 3 millimeter piece of skin. The resulting
hole heals rapidly. This entire procedure may
be performed with local anesthesia and is
usually done in the doctor's office.
Botulinum toxin (BTX - Botox) injection- This
is a procedure performed to alleviate a variety
of neurological conditions such as spasticity,
torticollis, hemifacial spasm, blepharospasm,
and occupational cramps (e.g., writers cramp).
A very small amount of toxin is injected
directly into the involved muscle(s). The
procedure takes ½ to 1 hour and is only a little
uncomfortable. Side effects are minimal but can
include bruising or infection from the needle
and less than 24 hours of generalized malaise.
Of note, the muscles injected will become
weakened in about 5-7 days. The weakness is
designed to reduce the activity of the overactive
muscle(s). In some cases, insufficient weakness
may require a reinjection and in some cases,
excessive weakness may temporarily interfere
with the injected muscles functioning.
Botulinum toxin continued
There is also the risk of toxin spreading to
adjacent muscles and making them weak as
well. However, all weakness is temporary as
the effect of Botox lasts for about 3 months. If
the effect is beneficial, repeated injections will
be recommended.
Bradykinesia: The slowing of motor
movements due to dysfunction of the basal
ganglia and related structures. The gradual loss
of spontaneous movement; slowness of
voluntary movements.
Brainstem: The region of the brain consisting of
the medulla oblongata, pons, and midbrain.
The brainstem primarily contains white matter
interspersed with some gray matter. This area
of the brain serves as a two-way conduction
path, conveying nerve impulses between other
brain regions and the spinal cord. In addition,
most of the 12 pairs of cranial nerves from the
brain arise from the brainstem, regulating
breathing, digestion, heartbeat, blood pressure,
pupil size, swallowing, and other basic
functions.
Broca's aphasia - This is a form of aphasia in
which speech output is severely reduced and is
limited mainly to short utterances, of less than
four words. Vocabulary access is limited in
persons with Broca's aphasia, and their
formation of sounds is often laborious and
clumsy. The person may understand speech
relatively well and be able to read, but be
limited in writing. Broca's aphasia is often
referred to as a 'non fluent aphasia' because of
the halting and effortful quality of speech.
Bruxism:
Involuntary grinding, clenching, or gnashing of
the teeth, particularly during sleep or times of
stress. Without appropriate protection, such as
the use of night guards that cover the teeth,
severe dental problems may result.
Bruxism continued
Bruxism may also be a feature of certain
neurologic movement disorders, including
dystonia of the jaw, mouth, and lower face
(oromandibular dystonia [OMD]), Rett
syndrome, or tardive dyskinesia
CT or CAT Scan:
The computed tomographic scan (also called a
CT or CAT scan) uses an x-ray beam and a
computer to generate 2 dimensional images of
the body. The information is displayed in a
cross-section or "slice" of body tissue.
Neurological CT scans focus on the head or
spine.
Carbonic anhydrase inhibitors: A class of
medications that inhibits activity of the enzyme
carbonic anhydrase. Carbonic anhydrase
activity serves to accelerate the transfer of
carbon dioxide from tissue to the blood and on
to the lungs. By restricting carbonic anhydrase
activity, these agents decrease hydrogen ion
concentrations in the renal tubules, increasing
excretion of sodium, potassium, bicarbonate,
and water. Certain carbonic anhydrase
inhibitors are prescribed to promote urinary
production and excretion (i.e., as diuretics) or to
lower fluid pressure within the eyes for those
with glaucoma. They are also used to treat
other conditions including epilepsy or certain
neurologic movement disorders
Carnitine: A natural substance found in
skeletal and cardiac muscle and the liver.
Carnitine serves to transport fatty acids across
mitochondrial membranes, thereby playing an
important role in energy production and the
metabolism of fatty acids.
Caudate nucle: One of the 3 major
substructures that, together with the globus
pallidus and putamen, form the basal ganglia.
The caudate nuclei and putamen, which are
relatively similar structurally and functionally,
Caudate nucle continued
are collectively known as the striatum.
Specialized clusters of nerve cells or nuclei
within the caudate receive input from certain
regions of the cerebral cortex. This information
is processed and then relayed (by way of the
thalamus) to areas of the brain responsible for
controlling complex motor functions.
The caudate nuclei are specifically thought to
process and transmit cognitive information that
influences the initiation of complex motor
activities.
cataplexy: A symptom characterized by the
sudden loss of postural tone, often resulting in
the individual falling to the floor. Cataplexy is
often part of the narcolepsy complex.
Central nervous system (CNS): The brain and
spinal cord. The CNS, which receives sensory
impulses from and sends motor impulses to the
peripheral nervous system (i.e., nerves outside
the CNS), plays an essential role in the
coordination and control of the entire body.
Central oscillators: nerve cells that discharge
signals that result in alternating fluctuations of
electrical impulses along certain tracts of the
central
nervous system.
Cerebellum: A two-lobed region of the brain
located behind the brainstem. The cerebellum
receives messages concerning balance, posture,
muscle tone, and muscle contraction or
extension.
Working in coordination with the basal ganglia
and thalamus, the cerebellum integrates,
adjusts, and refines messages transmitted to
muscle groups from the cerebral cortex (i.e.,
motor cortex). Thus, the cerebellum plays an
essential role in producing smooth, coordinated
voluntary movements; maintaining proper
posture; and sustaining balance.
Cerebral cortex: The outer region of the brain's
cerebral hemispheres. Comprised of gray
matter, the cerebral cortex contains several
deep folds (gyri) and grooves (sulci or fissures).
Two sulci divide the surfaces of both cerebral
hemispheres into four distinct lobes that are
named for overlying bones of the skull. These
include the frontal, temporal, occipital, and
parietal lobes. The cerebral hemispheres are
joined by a thick band of nerve fibers known as
the corpus callosum. The cerebral cortex is
responsible for integrating higher mental
functioning and conscious thought, sensations,
and general movements.
Cerebrospinal fluid (CSF): The fluid that flows
through and protects the 4 cavities (ventricles)
of the brain, the spinal cord's central canal, and
the space (known as the subarachnoid space)
between the middle and inner layers of the
membrane (meninges) enclosing the brain and
spinal cord. Laboratory analysis of CSF, usually
obtained via lumbar puncture, may help to
diagnose central nervous system infections,
certain tumors, or particular neurologic
disorders. During lumbar puncture, CSF is
removed from the spinal canal via a hollow
needle inserted between certain bones of the
spinal column within the lower back (i.e.,
usually the third and fourth lumbar vertebrae).
Chemodenervation: Interruption of a nerve
impulse pathway via administration of a
chemical substance, such as botulinum toxin
(BTX). For example, intramuscular injections of
BTX produce local relaxation of treated muscles
by inhibiting the release of acetylcholine, a
neurotransmitter that is present at the junctions
of nerve and muscle cells and that regulates the
delivery of messages from neurons to muscle
fibers.
Chorea: Chorea, which means dance-like, is a
movement that flows from joint to joint. In mild
cases, the patient can cover these movements
by incorporating them into other movements
such as raising the hand to the head to brush
ones hair or by sitting on ones hands.
Chorea continued:
Chorea may affect the face (grimaces, tongue
protrusion, chewing), neck and trunk
(swaying), limbs (restlessness), posture (motor
impersistence), or gait (halting or lurching). An
intermittently relaxing and tightening grip
(milkmaid grasp) is one example of motor
impersistence.
Chorea may be more prominent during action,
stress, or other emotions. Like myoclonus, the
list of causes of chorea is extensive, but it is
useful to differentiate between primary
hereditary conditions and secondary ones,
commonly infrections and drug reactions.
Although one of the best known choreatic
disorders is Huntington chorea, chorea is rare
in the childhood-onset form (Westphal or
akinetic rigid variant), but dementia and
seizures are typical. Chorea is one of the
significant manifestations of rheumatic fever.
Is worsened by stress, anxiety, or depression, is
decreased during sleep, and often varies with
posture or positioning. Various assistive
devices maybe helpful. These include padded,
reclining chairs, padding for the bed, andwrist
and ankle weights to reduce the amplitude of
the chorea.
Pharmacologic (drugs) treatment of chorea may
worsen other aspects of the movement
disorder, cognition or mood. Is the chorea
severe enough to interfere with voluntary
activities such as writing, cooking, or eating?
Does severe chorea seem to be causing falls or
accidents? Is highly visible chorea a significant
source of distress for the patient?
Central nervous system: Refers to the brain
and the spinal cord.
Cerebrospinal fluid: The fluid that surrounds
the brain and the spinal cord
Chorionic villus sampling (CVS):
A screening and diagnostic procedure
performed during which tissue samples are
obtained from a portion of the placenta using a
specially guided needle via ultrasound. The
placenta is the organ attached to the lining of
the uterus that links the blood supplies of the
developing fetus and the mother. The tissue
sample is obtained from the layer from which
the chorionic villi develop. Blood from the fetus
flows through the umbilical cord
to the placenta and enters minute blood vessels
arranged in multiple "thread-like" projections
or chorionic villi surrounded by maternal
blood. Tissue samples obtained during
chorionic villus sampling are analyzed to detect
certain genetic or chromosomal abnormalities.
Chromosomes: The thread-like structures
within the nuclei of cells comprised of DNA.
Deoxyribonucleic acid or DNA carries genetic
information involved in directing cellular
activities, thus controlling bodily growth and
functioning and determining the expression of
inherited traits. The chromosomes contain
thousands of hereditary units known as genes
or segments of DNA molecules.
CLONUS: An abnormal movement
characterized by rapid contraction and
relaxation of muscles. Brisk increase in tone
with involuntary movements that result in
dysfunction of the corticospinal tracts.
Clonus is frequently observed in conditions
such as spasticity and certain seizure disorders.
Confabulation (fabricating answers)
Patients with severe frontal lobe lesions tend to
fabricate quick, impulsive answers to questions.
Some responses may be quite fanciful and
imaginative. The patient cannot inhibit a
response in order to check its validity. For
example, when asked, "How did you get to the
hospital?", the patient may respond with an
imaginative tale that has very little relationship
to the truth.This tendency to fabricate an
answer is called confabulation.
Confabulation continued
It is most common among patients with basal
forebrain lesions and among patients with
additional impairment of memory ability.
Computerized tomography (CT) imaging or
scanning: An advanced diagnostic scanning
technique during which cross-sectional images
of tissues and organs are produced by passing
x-rays through the body at various angles. In
some cases, a contrast medium, which is
opaque on x-rays, may be injected
intravenously to produce enhanced images of
certain tissues, organs, or blood vessels
Congenital: Existing at birth.
Contractures: Fixed resistance to passive
stretching of certain muscles due to shortening
or wasting (atrophy) of muscle fibers or the
development of scar
tissue (fibrosis) over joints.
Contralateral: the opposite side. For example,
during brain surgery for essential tremor, if the
surgery is performed on the right side of the
brain, the left side
of the body will be affected.
Corticobasal degeneration (CBD): A slowly
progressive disorder characterized by
neurodegenerative changes of certain brain
regions, including the cerebral cortex
(particularly the frontal and parietal lobes) and
parts of the basal ganglia.
Most patients initially develop symptoms in
their 60s or 70s. Primary findings may include
stiffness (rigidity); slowness of movement
(bradykinesia); loss of the ability to coordinate
and execute certain purposeful movements of
the arms or legs (limb apraxia); the sensation
that a limb is not one's own ("alien limb
phenomenon"); and other sensory
abnormalities.
Corticobasal degeneration (CBD) continued
Affected individuals may also develop slurred,
labored speech (dysarthria); dystonia; and
irregular, involuntary, "shock-like" contractions
of certain muscle groups, particularly of the
hands and forearms, that may be provoked or
aggravated by voluntary movement and certain
external stimuli (action and reflex myoclonus)
corticospinal tract: The nervous system
structures that begin in the brain and travel to
the motor neuron cell to innervate the motor
nerves. Referring to or connecting the outer
region of the brain (cerebral cortex) and the
spinal cord.
Cranial: Of or from the cranium or skull.
Cranial nerve nuclei: Specialized groups of
nerve cells (nuclei) that give rise to and convey
or receive impulses from sensory and motor
constituents of the cranial nerves, which are the
12 pairs of nerves that emerge from the brain.
These nerve pairs convey sensory impulses for
various functions including taste, smell,
hearing, and vision; motor impulses involved
in controlling eye movements, chewing,
swallowing, facial expressions, etc.; and
impulses for transmission to certain organs and
glands for regulation of various involuntary or
autonomic activities.
Cranial neuropathy: Disease or damage of a
cranial nerve or nerves. The cranial nerves are
the 12 nerve pairs that arise directly from the
brain and are involved in conveying impulses
for various functions including smell, hearing,
vision, and taste; pupil contraction; eye
movements; facial expressions; movements of
the tongue, head, and shoulders; etc.
Cranial neuropathy may result in associated
muscle weakness; abnormal sensations, such as
numbness, tingling, or pain; or other findings.
Specific symptoms depend upon the specific
nerve(s) affected.
Creutzfeldt-Jakob disease (CJD):
A rare, degenerative, life-threatening brain
disorder characterized by severe, progressive
dementia; visual disturbances; muscle
weakness; and abnormal involuntary
movements, such as sudden, brief, "shock-like"
muscle spasms (myoclonus), tremor, and
relatively slow writhing motions that appear to
flow into one another (athetosis). Although CJD
usually appears to occur sporadically, about 10
percent of cases are familial, potentially
suggesting a hereditary predisposition to the
disease.
Deep brain stimulation (DBS) is used for
treatment of a movement disorder, during the
procedure a recording electrode is often first
used to determine exactly where to place the
stimulation electrode. The recording electrode
can measure the electrical activity in the brain
directly.
deep tendon reflexes: The deep muscle stretch
reflexes that are obtained by tapping on the
tendons (such as the "knee jerk").
Degenerative: Marked by or pertaining to
deterioration; particularly, deterioration of the
function or structure of tissue or changes from a
higher to a lower or less functionally active
form.
Dementia An acquired loss of cognitive
function that may affect language, attention,
memory, personality and abstract reasoning.
Dementia is a condition of impairment of
memory, intellect, personality, and insight
resulting from brain injury or disease. Some
forms of dementia are progressive, such as
Alzheimer's disease, Picks disease, or some
forms of Parkinson's disease. Language
impairments are more or less prominent in
different forms of dementia, but these are
usually overshadowed by more widespread
intellectual loss. Since dementia is so often a
progressive disorder, the prognosis is quite
different from aphasia.
Dendrites: The relatively narrow, branching
projections that extend from the cell bodies of
neurons. Nerve cells may contain multiple
dendrites, which are stimulated by
neurotransmitters, receive impulses from the
nerve fibers (axons) of other neurons, and
convey them toward their nerve cell bodies.
Dentatorubropallidoluysian atrophy:
A rare genetic disorder that is most commonly
described in Japan. Associated symptoms may
become apparent in adolescence or adulthood.
Early-onset disease may be characterized by
rapidly progressive neurodegenerative
changes, including seizures, cognitive
impairment, and brief, "shock-like" muscle
spasms of certain muscles or muscle groups
(myoclonus). Late-onset disease may be
associated with progressively impaired control
of voluntary movement (ataxia) and symptoms
often seen in Huntington's disease (HD),
including chorea and gradual loss of thought
processing and acquired intellectual abilities
(dementia). Brain imaging studies typically
reveal degenerative changes of the globus
pallidus and specialized nerve cell clusters
within the cerebellum (dentate nucleus).
Similar to HD, the disorder may result from
abnormally long sequences or "repeats" of
particular coded instructions (unstable
expanded CAG repeats) within a gene (located
on chromosome 12).
Diaphragm: The dome-shaped muscle that
separates the chest and abdomen. The
diaphragm plays an essential role in breathing,
contracting when air is drawn into the lungs
and relaxing upon exhalation.
Differential diagnosis: Distinguishing between
two or more diseases and conditions with
similar symptoms by systematically comparing
and contrasting their clinical findings,
including physical signs, symptoms, as well as
the results of laboratory tests and other
appropriate diagnostic procedures.
DNA: deoxyribonucleic acid; a two-stranded
molecule that contain the genes that provide
the blueprint for all of the structures and
functions of a living being. Most human DNA
is nDNA, which is a huge molecule that is
folded tightly and stored in the nucleus of the
cell. MtDNA is a much smaller molecule stored
in the mitochondria.
Dysarthria: Disordered or impaired articulation
of speech due to disturbances of muscular
control, usually resulting from damage to the
central or peripheral nervous system.
Dysarthria is associated with certain
neurodegenerative disorders, such as
Parkinson's disease or Huntington's disease;
cerebral palsy; brain tumors or stroke; or
certain types of brain surgery.
A difficulty with the physical production of
speech, results largely from impairment of
voluntary movement. Speech becomes slurred,
dysrhythmic, variable in volume due to
inconsistent breath support, and increasingly
difficult to understand. Some patients do not
seem to be aware of distortions in their speech.
For others, articulation is a constant source of
frustration.
No medications are known to be helpful, and
dysarthria may be worsened by agents which
suppress chorea.
However, several interventions may enhance
communication in these patients. A
communication board can also be useful in
some cases. A speech-language pathologist may
be able toprovide additional insights and
management strategies. Dysarthria may be
compounded by cognitive problems found in
HD, such as word-finding difficulty, difficulty
initiating speech, or difficulty completing a
sentence. Unlike apraxia of speech, the speech
errors that occur in dysarthria are highly
consistent from one occasion to the next. Links:
Dysarthria
Dyskinesias: Abnormal neuromuscular
conditions characterized by disorganized or
excessive movement (also known as
hyperkinesia). Forms of dyskinesia include
sudden, brief, "shock-like" muscle contractions
(myoclonus); involuntary, rhythmic, oscillatory
movements of a body part (tremor); rapid
involuntary jerky movements (chorea);
relatively slow writhing motions (athetosis); or
abrupt, purposeless, simple or complex muscle
movements or vocalizations (motor or vocal
tics).
Dyskinesias while awake (DWA):
Uncontrolled, sporadic movements of the legs
and, in some cases, the arms. These movements
may be very rapid (myoclonic) or quite slow
and prolonged (dystonic); they usually
disappear upon voluntary action. Some
researchers suspect that these move-ments may
represent a wakeful form of periodic limb
movements in sleep (PLMS).
Dysphagia: Difficulty in swallowing.
Dysphagia may be associated with esophageal
obstruction as well as certain
neurodegenerative or motor disorders
involving the esophagus.
Results from impaired voluntary control
of the mouth and tongue, impaired respiratory
control due to chorea, and impaired judgment,
resulting in eating too rapidly, or taking overly
large bites of food and gulps of liquid. Dry
mouth, which can be brought on by
neuroleptics, anti-depressants, and
anticholinergics, may worsen the problem.
No medications are known to improve
swallowing directly. Early referral to a speechlanguage pathologist will help identify
swallowing difficulties, and periodic reassessment can identify changes in swallowing
ability and suggest appropriate nonpharmacologic interventions such as a change
in food consistency.
Dysphagia: Difficulty in swallowing continued
Devices such as enlarged grips tor silverware
and nonslip plates with raised edges to prevent
spilling may prolong independent eating.
DYSPHASIA: Lack of coordination in speech,
and failure to arrange words in an understandable way; due to brain lesion. Aphasia is
the complete or near complete absence of
speech, and is used to describe a more severe
situation than dysphasia.
Dyspraxia: Partial loss of the ability to
coordinate and perform certain purposeful
movements and gestures in the absence of
motor or sensory
impairments.
Dystonia: A neurologic movement disorder
characterized by sustained muscle contractions,
resulting in repetitive, involuntary, twisting or
writhing movements and unusual postures or
positioning. Dystonia may be limited to specific
muscle groups (focal dystonia), such as
dystonia affecting muscles of the neck (cervical
dystonia or spasmodic torticollis) or the eyes,
resulting in closure of the eyelids
(blepharospasm).
Dystonia is associated with certain underlying
genetic disorders, such as dystonia musculorum deformans, dopa-responsive dystonia,
and paroxysmal kinesigenic and paroxysmal
non-kinesigenic dystonic choreoathetosis.
It can result in twisted, contorted postures of
the body or limbs. The movements are usually
slow and may appear exaggerated.
There are many causes of this movement
disorder, which include biochemical
abnormalities, degenerative disorders,
psychiatric dysfunction, toxins, and drugs. The
condition may result from the use of certain
medications, lack of oxygen during or
immediately after birth, or other causes of brain
trauma. Many forms of dystonia are not well
understood and occur as a primary syndrome.
Dystonic: Referring to dystonia; sudden jerky
or repetitive movements and muscle spasms
due to impaired muscle tone and abnormal
muscle rigidity.
Electrical stimulation (ES): A test in which a
small electrical charge is applied to a muscle via
a needle to determine the level of muscle
responsiveness.
Electroencephalography (EEG): A noninvasive,
diagnostic technique that records the electrical
impulses produced by brain cell activity. An
EEG reveals characteristic brain wave patterns
that may assist in the diagnosis of particular
neurologic conditions, such as seizure
disorders, impaired consciousness, and brain
lesions or tumors.
Electrodiagnostic tests
(i.e., electromyography (EMG) and nerve
conduction velocity, or NCV) - studies that
evaluate and diagnose disorders of the muscles
and motor neurons. Electrodes are inserted into
the muscle, or placed on the skin overlying a
muscle or muscle group, and electrical activity
and muscle response are recorded.
EEG: (electroencephalography) The diagnostic
test that is used to study the brain wave
activity. It is most useful to evaluate the seizure
disorders.
EMG/NCV: (electromyography/nerve
conduction study) A test that is used to study
the nerves and muscles to help diagnose
disorders that can affect
them. A small needle is placed in the muscle in
the EMG. Electrical conduction is studied in the
NCV. The results are seen on an oscilloscope
screen and compared to normal values. During
this test, a small needle is inserted into a muscle
to record the level of activity
Electrophysiologic studies: The study of the
electrical activity associated with a specific
body function (e.g., EMG, EEG, etc.).
ENCEPHALOPATHY: Any disease of the
brain.
ENZYME: A protein that speeds up a chemical
reaction or causes a chemical change in another
substance. Enzymes do their work without
being changed or used up in the process. A
chemical substance that is acted upon by an
enzyme is called a "substrate." In many cases,
enzymes are named by adding the suffix "-ase"
to the name of the substrate upon which the
enzyme exerts its action.
Epilepsy (Seizures) Said to be present in 30%
of individuals with juvenile-onset HD. A first
seizure in an HD patient should not be
attributed to HD without further evaluation as
it may be indicative qf an additional neurologic
problem, such as a subdural hematoma
sustained in a fall.
The treatment of a seizure disorder in a person
with HD depends on the nature of the seizures.
In the juvenile HD patient, myoclonic epilepsy
or other generalized seizures may suggest
divalproex sodium as a first treatment choice.
Although seizure management in HD is not
usually difficult, for the occasional patient
seizure control is quite difficult to achieve,
requiring multiple medications or specialized
referral.
Ergot: A plant alkaloid produced by the fungus
Claviceps purpurea.
Ergot-derived medication: A medication that
has a chemical structure based on ergot, a plant
alkaloid produced by a fungus called Claviceps
purpurea. Permax® and Parlodel® are
examples of ergot-derived medications that
may be used to treat certain neurologic
movement disorders.
Esophageal atony: Lack of normal muscle tone
within the esophagus, the muscular tube that
transports food from the throat to the stomach.
Essential tremor (ET): A common, slowly and
variably progressive neurologic movement
disorder characterized by involuntary,
rhythmic, "back and forth" movements (i.e.,
tremor) of a body part or parts. In ET patients,
tremor is primarily a "postural" or "kinetic"
tremor or may be a combination of both types:
i.e., tremor occurs while voluntarily maintaining a fixed position against gravity
(postural tremor) and/or when conducting selfdirected, targeted actions (kinetic intention
tremor). ET may appear to occur randomly for
unknown reasons (sporadically) or be
transmitted as an autosomal dominant trait.
This form of tremor is maximal when the body
part is being used, such as when writing or
when making fine coordinated hand
movements. It is less common when at rest.
Extrapyramidal system:
Refers to central nervous system structures (i.e.,
outside the cerebrospinal pyramidal tracts) that
play a role in controlling motor functions. The
extrapyramidal system includes substructures
of the basal ganglia and the brainstem and
interconnections with certain regions of the
cerebellum, cerebrum, and other areas of the
central nervous system. Extrapyramidal
disturbances may result in postural and muscle
tone abnormalities as well as the development
of certain involuntary movements.
Falls
Falls are common in persons with HD, and can
be a source of significant morbidity. Usually
seen more in the moderate to advanced stages,
they often result from the combination of
spasticity, rigidity, chorea, and loss of balance.
Pharmacotherapy (drugs) to prevent falls could
include treatment of chorea, rigidity, spasticity
and dystonia, while minimizing the use of
drugs such as neuroleptics and benzodiazepines, whose side effects include
sedation,ataxia, or parkinsonism.
Falls continued
Most efforts at prevention, however, involve
not drugs, but modification of the environment
and behavior of the patient.
Occupational and physical therapists can
instruct patients in how to sit, stand, transfer,
and walk more safely.
Fasciculation: Twitching of the muscles that is
seen in diseases involving the peripheral
nervous system.
Free radicals: Unstable molecular fragments
that can damage cells.
Frequency: number of cycles or repetitions
within a fixed unit of time such as the number
of cycles per second (Hertz or Hz). For
example, essential tremor is typically 4 to 12
Hz.
Froment's sign: Increased resistance to passive
movements of a limb that may be detected
upon voluntary activity of another body part.
Functional Magnetic Resonance Imaging
(fMRI): A noninvasive, diagnostic scanning
procedure that produces detailed,
computerized images. The use of a "contrast
agent" or dye enhances the detail of the images.
Sequencing of these images may help
physicians visualize the body's functioning,
thus aiding differential diagnosis.
Gadolinium: A contrast agent that is given
intravenously during MRI (magnetic resonance
imaging) to increase visualization of specific
abnormalities
Gait: The style or manner of walking. Gait
disturbances may be associated with certain
neurologic or neuromuscular disorders,
orthopedic conditions, inflammatory conditions
of the joints (i.e., arthritic changes), or other
abnormalities.
Gait apraxia (walking)
Loss of the ability to consciously sequence and
execute the movements required to coordinate
walking. Gait apraxia may result in unsteady
walking patterns; "toe-walking"; a widely
based, jerky gait; and balance difficulties. It is
an abnormality in which the patient is able to
carry out all of the movements required for gait
normally when lying down, but is unable to
walk in the standing position, thought to be
associated with frontal disorders or normal
pressure hydrocephalus.
Gamma-aminobutyric acid (GABA): An amino
acid neurotransmitter that inhibits or decreases
the electrical activities of nerve cells. GABA is
the primary inhibitory neurotransmitter in the
brain
Gastrostomy tube: (feeding tube)
A plastic tube inserted into the stomach
through a surgical incision in the abdomen. A
gastrostomy tube is used to deliver liquified
food to the digestive system when swallowing
becomes dangerous or difficult.
Genetic anticipation: A phenomenon in which
the onset of symptoms of a hereditary disease
appears to occur at a progressively earlier age
in successive generations. Genetic anticipation
has been demonstrated in a number of
hereditary disorders (such as Huntington's
disease, dentatorubropallidoluysian atrophy,
etc.) in which the gene mutation consists of
abnormally long sequences or "repeats" of
particular coded instructions (e.g., unstable
expansion of CAG repeats). With other
disorders in which genetic anticipation has
previously been suggested (e.g., essential
tremor), studies have indicated that increased
awareness of the condition in affected families
may be responsible for earlier recognition of
symptom onset.
GENE: The fundamental unit of heredity.
Genes are located on strands of DNA found in
the cells and mitochondria.
Genetic heterogeneity: Manifestation of similar
or the same observable characteristics or traits
(i.e., phenotype) resulting from different
genetic mechanisms, such as changes
(mutations) of different genes or a combination
of genes.
Gliosis: A proliferation of astrocytes in
damaged areas of the central nervous system
(CNS). Astrocytes are relatively large glial cells,
which are the connective tissue cells of the
CNS. Astrocytes have various functions,
including accumulating in areas where nerve
cells (neurons) have been damaged. Gliosis and
neuronal loss in certain brain regions are
findings seen in various neurodegenerative
disorders.
Global aphasia - This is the most severe form
of aphasia, and is applied to patients who can
produce few recognizable words and understand little or no spoken language. Global
aphasics can neither read nor write. Global
aphasia may often be seen immediately after
the patient has suffered a stroke and it may
rapidly improve if the damage has not been too
extensive. However, with greater brain
damage, severe and lasting disability may
result.
Globus pallidus: A major substructure of the
basal ganglia deep within the brain. Specialized
groups of nerve cells in the globus pallidus
function as an "intermediate relay system." This
system processes and transmits information
from the basal ganglia by way of the thalamus
to areas of the brain that regulate complex
motor functions (e.g., motor cortex, premotor
area of frontal lobe
Glutamate: An amino acid that is a primary
excitatory neurotransmitter in the central
nervous system. This chemical agent plays an
essential role in initiating and transmitting
nerve impulses, crossing synapses to stimulate
postsynaptic neurons.
Gray matter: Nerve tissue that primarily
consists of nerve cell bodies, dendrites, and
unmyelinated axons, thus having a gray
appearance. In contrast, white matter
predominantly contains myelinated nerve
fibers.
Hallucinations continued
Hallucinations may occur with high-dose
administration of certain medications or the
abuse of particular drugs (hallucinogens) that
cause increased stimulation or excitation of the
central nervous system.
Globus pallidus: A major substructure
of the basal ganglia deep within the brain.
Specialized groups of nerve cells in the globus
pallidus function as an "intermediate relay
system." This system processes and transmits
information from the basal ganglia by way of
the thalamus to areas of the brain that regulate
complex motor functions (e.g., motor cortex,
premotor area of frontal lobe).
They may also be caused by chronic alcohol
abuse; sensory deprivation; certain types of
seizures due to impairment or damage of a
limited area of the brain (e.g., temporal lobe
epilepsy); psychotic illnesses characterized by
disturbances in thought, behavior, and
emotional reactions (schizophrenia); or certain
organic disorders, such as Huntington's
disease.
Hallervorden-Spatz disease:
A slowly progressive hereditary disorder
characterized by abnormal accumulations of
iron pigments in certain regions of the basal
ganglia (e.g., globus pallidus and substantia
nigra). This autosomal recessive disorder
typically becomes apparent during late
childhood or adolescence.
Hemichorea: Irregular, abrupt, relatively rapid
involuntary (i.e., choreic) movements that are
unilateral or involve muscle groups on one side
of the body.
Associated symptoms may include progressive
stiffness and resistance to movement (rigidity);
increasing difficulties speaking and eating;
sustained muscle contractions that result in
repetitive twisting motions or unusual postures
or positions (dystonia); the presence of
multiple, irregular, jerky motions that may
combine to appear flowing or writhing in
nature (choreoathetosis); and/or other
abnormalities.
Hallucinations: Perceptions that occur in the
absence of external stimuli and while an
individual is awake. Hallucinations may
involve any of the senses, including hearing
(auditory hallucinations), vision (visual
hallucinations), smell (olfactory hallucinations), taste (gustatory hallucinations), and
touch (tactile hallucinations).
Hemiparesis: Weakness that affects one side of
the body.
Hereditary: Inherited; inborn; referring to the
genetic transmission of a trait, condition, or
disorder from parent to offspring.
Heredodegenerative: Pertaining to genetically
transmitted (hereditary) neurologic disorders
characterized by progressive neuronal loss and
other neurodegenerative changes (e.g.,
associated gliosis). For example, the term
"heredo-degenerative dystonias" is used to refer
to several, usually hereditary disorders in
which neurodegenerative changes may lead to
dystonia as a primary feature and other
neurologic symptoms are typically present.
However, in some patients with such disorders,
dystonia may not always develop and other
neurologic features may be primary findings.
Disorders that have been categorized as
heredodegenerative dystonias include ataxia-
Heredodegenerative continued
telangiectasia, Hallervorden-Spatz disease,
Huntington's disease, Parkinson's disease,
progressive supranuclear palsy, neuroacanthocytosis, and Wilson's disease.
Homocystinuria: A metabolic abnormality
characterized by excessive amounts of the
amino acid homocystine in the urine.
Homocystinuria, which may be transmitted as
an autosomal recessive trait, may result from
deficient activity of certain enzymes involved in
the metabolic conversion of the amino acid
methionine to cysteine.
hemorrhage: Bleeding; (such as in brain
hemorrhage)
Huntington's disease (HD):
A hereditary, progressive, neuro-degenerative
disorder primarily characterized by the
development of emotional, behavioral, and
psychiatric abnormalities; gradual deterioration
of thought processing and acquired intellectual
abilities; and movement abnormalities,
including involuntary, rapid, irregular jerky
movements (chorea) of the face, arms, legs, or
trunk.
HD may be inherited as an autosomal
dominant trait or, less commonly, appear to
occur randomly for unknown reasons
(sporadically). The disorder results from
abnormally long sequences or "repeats" of
certain coded instructions (i.e., unstable
expanded CAG repeats) within a gene (located
on chromosome p16.3). Progressive nervous
system dysfunction associated with HD results
from loss of neurons in certain areas of the
brain, including the basal ganglia and cerebral
cortex.
Hyperkalemic: Pertaining to hyperkalemia, a
condition characterized by unusually high
concentrations of potassium in the blood.
Potassium, a positively charged ion, helps to
regulate water balance, nerve conduction, and
muscle contraction.
Hyperkalemia continued
Hyperkalemia may lead to various signs and
symptoms, such as diarrhea, nausea, abdominal
cramps, weakness, and, with increasing
severity, abnormal heart rhythms and muscle
paralysis.
Hyperkinetic: Characterized by excessive
movement because of abnormally increased
motor activity or function. Certain movement
disorders are termed "hyper-kinetic" such as
tics or essential tremor.
Hyperventilation: Abnormally rapid breathing
usually accompanied by air swallowing.
Hyperventilation results in excessive intake of
oxygen and increased elimination of carbon
dioxide, which may eventually lead to a
disturbance in the body's acid-base balance.
Hypokinetic: Diminished movement and
decreased motor function. Some movement
disorders are hypokinetic, such as Parkinson's
disease.
Hypoparathyroidism:
An endocrine condition characterized by
insufficient secretion of parathyroid hormone
due to injury, disease, or congenital abnormalities of the parathyroid glands. Parathyroid
hormone plays an essential role in regulating
calcium balance in the body.
Hypoparathyroidism results in low calcium
blood levels (hypocalcemia), leading to various
symptoms and findings. For example, hypoparathyroidism may cause a condition known
as tetany in which increased excitability of
nerves and muscles results in uncontrollable,
painful muscle spasms and cramping;
abnormal involuntary movements resembling
chorea; spasmodic closure of the larynx
(laryngospasm); and other findings. Hypoparathyroidism may also lead to seizures;
abnormal calcium deposits (calcifications) in
the basal ganglia; loss of transparency of the
lenses of the eyes (cataracts); dry, scaly skin;
weakened tooth enamel; and/or other
abnormalities.
Idiopathic: A disorder or condition of
spontaneous origin; self-originated or of
unknown cause. The term is derived from the
prefix "idio-" meaning one's own and "pathos"
indicating disease.
Idiopathic epilepsy: Recurrent seizures of
unknown origin or cause; repeated episodes of
uncontrolled electrical activity in the brain that
occur in the absence of detectable brain lesions.
Also known as essential or primary epilepsy,
these conditions are often thought to have a
genetic component. This may suggest that
affected individuals have an inherited
predisposition for recurrent seizures.
Immunogenicity: The ability to or the degree to
which a particular substance may provoke an
immune response; having the properties of an
antigen or any substance that may trigger a
particular immune reaction, such as the
production of anti-bodies.
Implantable Pulse Generator (IPG): A device
that is placed under the skin near the
collarbone as part of a surgical procedure
known as deep brain stimulation. Wire leads
from electrodes implanted in the brain are
connected to the pulse generator, which then
delivers continuous high frequency electrical
stimulation to the thalamus via the implanted
electrodes. This form of stimulation probably
"jams" the nucleus and therefore modifies the
message in the movement control centers of the
brain, serving to suppress tremor.
Inhibition: The restraint, suppression, or arrest
of a process or the action of a particular cell or
organ; the prevention or slowing of the rate of a
chemical or an organic reaction. The term
"reciprocal inhibition" refers to the restraint or
"checking" of one group of muscles upon
stimulation (excitation) and contraction
of their opposing (antagonist) muscles.
Inhibitor: A substance that blocks, restricts, or
interferes with a particular chemical reaction or
other biologic activity.
Innervate: To supply a body part, tissue, or
organ with nerves or nervous stimulation.
Insidious:
Of subtle, gradual, or imperceptible
development; referring to the development of
symptoms that may not be recognized by an
affected individual until the disorder in
question is established.
Ion: An electrically charged atom or group of
atoms due to the loss or gain of one or more
electrons. Positively charged ions, known as
cations, include potassium, calcium, sodium,
hydrogen, ammonium, and magnesium.
Negatively charged ions, called anions, include
chloride, phosphate, and bicarbonate.
The transfer of ions across cellular membranes
plays an essential role in vital bodily processes,
including enzyme activation, protein
metabolism, acid-base balance, nerve impulse
transmission, and muscle contraction.
Joint contractures: Permanent flexing or
extension of joints in fixed postures due to
shortening of muscle fibers. Contractures,
abnormal fixation of the limbs, and associated
deformity may result from prolonged
immobility of developing joints.
Juvenile myoclonic epilepsy: A form of
idiopathic epilepsy or recurrent seizures of
unknown origin, with symptom onset typically
occurring from approximately
12 to 16 years of age. The condition is
characterized by sudden, involuntary, "shocklike" muscle jerks (myoclonus) that primarily
occur during the morning or with stress,
fatigue, or alcohol consumption. Patients may
later develop generalized tonic-clonic seizures
associated with loss of consciousness and
rhythmic contraction and relaxation of all
muscle groups.
Kinematics is the study of the position of the
limbs.
Kinesigenic: Caused by sudden voluntary
movement; movement induced. More
specifically, this term is often used to describe
abrupt episodes of involuntary movement that
are provoked by sudden motions or unexpected
stimuli.
Lafora's disease: A progressive myoclonic
encephalopathy (PME) that is inherited as an
autosomal recessive trait. Associated symptoms
typically begin in childhood or early
adolescence and include frequent seizures
characterized by loss of consciousness and
rhythmic contraction and relaxation of all
muscle groups (generalized tonic-clonic
seizures); sudden, involuntary, "shock-like"
muscle jerks (myoclonus); and rapidly
progressive deterioration of thought processing
and acquired intellectual abilities (dementia).
Removal and microscopic examination of
minute tissue samples (e.g., muscle fibers, liver
cells, etc.) reveal abnormal, characteristic
deposits of complex proteins and carbohydrates
within the fluid portion of cells (intracytoplasmic inclusions known as "Lafora
bodies").
LACTATE or LACTIC ACID: A chemical that
is formed when sugars are broken down for
energy without the presence of adequate
oxygen. Lactic acid cannot be used by the body
and will accumulate in blood and urine. Lactic
acid causes the muscle pain when one runs too
fast for too long. In people with mitochondrial
disorders, lactic acid forms when the oxidative
capacity (ability to burn foods using oxidative
phosphorylation) of the person is impaired.
Lance-Adams syndrome: Also known as
"posthypoxic" or "postanoxic action myoclonus,"
this condition is characterized by the
development of chronic action myoclonus due
to a temporary lack or inadequate supply of
Lance-Adams syndrome continued
oxygen to the brain (cerebral hypoxia or
anoxia). Patients with action myoclonus
experience sudden, involuntary, "shock-like"
muscle contractions that may be triggered or
aggravated by voluntary movement. LanceAdams syndrome is also often associated with
cerebellar ataxia or lack of coordination,
postural imbalance, and other associated
findings.
Lacunar: A subtype of stroke that affects the
deeper parts of the brain and involves the tiny
perforating arteries.
Leigh disease: A disorder of mitochondrial
function that typically becomes apparent
during infancy. Also known as subacute
necrotizingencephalomyelopathy, the disorder
may be characterized by feeding and
swallowing difficulties, vomiting, muscle
weakness, low muscle tone (hypotonia), and
delayed acquisition of motor and language
skills. Affected infants and children may also
develop seizures; an impaired ability to
coordinate voluntary movements (ataxia);
involuntary, rapid, rhythmic eye movements
(nystagmus); tremor; dystonia; and/or other
abnormalities.
The disorder, which has a number of
underlying causes, may occur randomly for
unknown reasons (sporadically) or be
transmitted as an autosomal recessive or Xlinked trait. Leigh disease is associated with
characteristic changes of the central nervous
system (CNS), including symmetric regions of
localized tissue loss (necrosis) and neurodegenerative changes of the basal ganglia,
thalamus, brainstem, spinal cord, and other
regions of the CNS.
Lumbar puncture: A procedure during which
a sample of fluid (i.e., cerebrospinal fluid
[CSF]) is removed from the spinal canal for
diagnostic or therapeutic purposes.
Lumbar puncture continued
During the procedure, CSF is obtained via a
hollow needle inserted between two bones of
the spinal column within the lower back (i.e.,
usually the third and fourth lumbar vertebrae).
Laboratory analysis conducted on CSF may help
to diagnose central nervous system infections,
certain tumors, or particular neurologic
disorders. In some cases, lumbar puncture may
also be performed to inject certain medications
into the CSF, such as particular anticancer
(chemotherapeutic) agents.
Lysosomal: Referring to lysosomes, which are
membrane-bound bodies (organelles) outside
the nuclei of cells that contain various enzymes
engaged in intracellular digestion.
Lysosomal storage diseases:
Inborn errors of metabolism in which deficiency
or impaired functioning of particular lysosomal
enzymes leads to an abnormal accumulation of
certain substances (e.g., fats, complex
carbohydrates) within particular cells,
progressively affecting multiple bodily tissues
and organs. (Lysosomes are membrane-bound,
enzyme-containing bodies within cells that
engage in digestive processes; enzymes are
proteins that accelerate the rate of certain
chemical reactions in the body.) Most lysosomal
storage disorders (e.g., mucolipidoses,
mucopolysaccharidoses, lipidoses, etc.) are
thought to be inherited as autosomal recessive
traits.
Magnetic resonance imaging (MRI): A
diagnostic scanning technique during which
radio waves and an electromagnetic field are
used to help create detailed, cross-sectional
images of specific organs and tissues.
MRI is often considered a particularly valuable
imaging technique for studies of the brain and
spinal cord because of the MRIs ability to scan
images from various angles and provide strong
contrast between healthy and abnormal tissues.
MAO-B inhibitors: Inhibitors of the enzyme
monoamine oxidase B. MAO-B helps break
down dopamine; inhibiting it prolongs the
action of dopamine in the brain.
Mean: An average; intermediate or middle
position in value, quantity, or degree. The
"arithmetic mean" is a statistical measure
derived by adding a set of values
and dividing the total by the number of values.
Medially: Toward the middle; closer to or
oriented toward the midline or median plane
of a body or structure. The "median plane"
refers to the imaginary plane that divides a
body into symmetrical parts.
MERFF syndrome (myoclonus epilepsy with
ragged-red fibers): A rare hereditary disorder
characterized by neurologic and muscle
abnormalities due to defects of genetic material
(DNA) in mitochondria, the rod-like structures
outside the nuclei of cells that serve as a
primary source of cellular energy. Removal
and microscopic examination of minute
samples of muscle fibers reveal structurally
abnormal mitochondria (a finding known as
"ragged-red fibers").
Associated symptoms include muscle
weakness; sudden, involuntary, "shock-like"
muscle contractions induced by voluntary
movements or in response to external stimuli
(action or reflex myoclonus); repeated seizures
(epilepsy); progressively impaired
coordination of voluntary movements (ataxia);
and/or gradual deterioration of intellectual
functioning (dementia).
Some affected individuals may also have
additional abnormalities, such as hearing loss;
degeneration of the nerves (i.e., optic nerves)
that convey impulses from the retinas to the
brain (optic atrophy); short stature; heart
muscle disease (cardiomyopathy); or other
findings.
Metabolic Tests - measurements of ammonia,
lactate, amino acids (as measured in blood and
urine, and sometimes CSF), and organic acids
(measured in urine). More specialized metabolic
tests include measurements of carnitine and
acylcarnitines, as well as white blood cell
enzyme function.
Monoamine: A molecule containing one amine
group. An amine is an organic compound
containing nitrogen. The so-called "biogenic
monoamines" are natural, biologically active
compounds that often function as neurotransmitters, including dopamine, serotonin,
noradrenaline, and epinephrine.
METABOLISM: The process of cells burning
food to produce energy. This is similar to a car's
engine (the cell's mitochondria) burning
gasoline (the food we eat) to produce the energy
or torque that turns the drive train that spins the
car's wheels (the energy we need to move and
think).
Monotherapy: A drug used alone to treat a
disease (opposite of combination therapy).
Refers to the ongoing chemical processes of cells
of the body, including catabolism and
anabolism. Catabolism or so-called "destructive
metabolism" is the breakdown of complex
chemical compounds into simpler substances,
typically liberating or releasing energy. In
contrast, anabolism or "constructive
metabolism" refers to the "building up" or
conversion of simple substances into more
complex chemical compounds, requiring energy
consumption (provided by catabolic processes.
MITOCHONDRIA: A part of the cell
(organelle) that is responsible for energy
production. The organelle consists of two sets of
membranes, a smooth continuous outer coat
and an inner membrane arranged in tubules or
in folds that form plate-like double membranes
(cristae); the principal energy source of the cell,
containing the cytochrome enzymes of terminal
electron transport and the enzymes of the citric
acid cycle, fatty acid oxidation, and oxidative
phosphorylation. Responsible for converting
nutrients into energy as well as many other
specialized tasks.
Mitochondrial: Referring to mitochondria or
rod-like structures inside cells of the body
whose primary functions include the production
and regulation of
energy.
Motor neuron cells: The cells located in the
spinal cord that give rise to the nerves that
supply the muscles.
Movement disorders can be classified into two
basic categories: those characterized by
disordered or excessive movement (termed
"hyperkinesia" or "dyskinesia "), and those that
are characterized by slowness, or a lack of
movement (termed "hypokinesia,"
"bradykinesia," or "akinesia").
An example of a "hyperkinetic" movement
disorder is a tremor or a tic while Parkinson's
disease can be classified as "hypokinetic,"
because it is often characterized by slow,
deliberate movements, or even "freezing" in
place.
Monoamine: A molecule containing one amine
group. An amine is an organic compound
containing nitrogen. The so-called "biogenic
monoamines" are natural, biologically active
compounds that often function as
neurotransmitters, including dopamine,
serotonin, noradrenaline, and epinephrine
mtDNA: Mitochondrial DNA contain the
genes that code for some of the enzymes and
some of the necessary molecules needed to
make those enzymes of the respiratory chain.
Mitochondria are the only part of the body cell
with their own separate and unique DNA.
Regardless, most of the mitochondria and the
respiratory chain are coded by nDNA. MtDNA
is inherited only from the mother.
multi-infarct dementia: A dementia that is
caused by the cumulative affect of having had
many strokes in the brain.
Multiple sclerosis (MS): A progressive disease
of the central nervous system characterized by
destruction of myelin (demyelination), the fatty
substance that forms a protective sheath around
certain long nerve fibers (axons). Myelin serves
as an electrical insulator, enabling the effective
transmission of nerve signals. Patients with MS
may develop paresthesias, such as numbness or
tingling; muscle weakness and stiffness;
impaired coordination; abnormal reflexes; an
inability to control urination (urinary
incontinence); slurred speech; visual
disturbances; and/or other symptoms and
findings.
Muscle tone: The low level of contraction in a
muscle not being intentionally contracted.
Mutation: A change in a gene, such as loss, gain,
or substitution of genetic material, that alters its
function or expression. This change is passed
along with subsequent divisions of the affected
cell. Gene mutations may occur randomly for
unknown reasons or may be inherited.
Myoclonic: Pertaining to myoclonus or
irregular, involuntary, shock-like contractions or
spasms of a muscle or muscle group
MYOCLONUS:
A single spasm or twitching of a muscle.
Myoclonus can be a single event (twitch) or
repeated events. Myoclonus can be a normal
event (the jerks that occur when we fall asleep)
or an abnormal event (those that occur while
awake, or those associated with seizures or
mitochondrial diseases). Clonus is the repeated
spasms of muscles, due to a seizure or increased
muscle tone.
Myodonus -sudden brief jerks involving
groups of muscles. It may be mistaken for a
seizure. Like chorea, myoclonus may not be
disabling or particularly distressing, but may
respond to treatment with clonazepam or
divalproex sodium if treatment is necessary
myopathy: A disease resulting in dysfunction
of the muscles usually causing weakness and
atrophy
"Olivopontocerebellar" implies involvement
and degeneration of the olives (structures in
the medulla, a part of the brainstem), the pons
(a part of the brainstem), and the cerebellum
(the part of the brain that controls coordination
and balance). Symptoms may include:
 ataxia
 kintetic tremor;
 dysarthria (difficulty with articulating
words)
 weakness;
 dystonia (the muscles may be in a state
of abnormal tension);
 chorea (irregular, spasmodic,
involuntary movement of the limbs or
facial muscles);
 spasticity (state of increased muscular
tone with exaggerated tendon
reflexes);
 kinetic tremor;
 degeneration of the retina;
 and neuropathy.
Opsoclonus-Myoclonus Syndrome:
The association of opsoclonus, myoclonus,
ataxia, and encephalopathy bears many names
such as Kinsbourne syndrome, dancing eyedancing feet, and infantile polymyoclonia.
Opsoclonus usually refers to conjugate,
chaotic, rapid eye movements. There is
generally no temporal association of
myoclonus with opsoclonus; myoclonus may
begin before or without opsoclonus.
Opsoclonus-Myoclonus Syndrome continued
Approximately half of the pediatric cases,
regardless of cause are encephalopathic, but
mental cloudiness is not usually a feature in
children. Tumors outside the CNS and viral
infections are the principal causes in children,
each accounting for about half of the cases. The
mean age at onset is about 18 to 20 months.
Several types of infection are associated with
opsoclonusmyoclonus; in children neural crestderived tumors such as neuroblastoma
predominate. Only 2-3% of neuroblastoma cases
are manifested as paraneoplastic opsoclonusmyoclonus syndrome.
Failure to find a neuroblastoma does not
preclude it as a cause of opsoclonus-myoclonus
because a neuro-blastoma may be difficult to
find due to the possibility of spontaneous
regression of the tumor. In 60% of patients the
tumor is found within 3 months, but there may
be a delay in diagnosing neuro-blastoma for up
to 4 years after opsoclonus-myoclonus first
appears.
PTOSIS: Droopy eyelids
Q- none
Range of motion (ROM): The extent of a joint's
free movement. The normal ROM of the elbow,
for instance, carries the forearm through a halfcircle. Passive ROM is tested while the limb is
relaxed. Active ROM is movement controlled by
the patient.
Receptor: A molecule on a neuron that receives
a neurotransmitter. Reception of the
neurotransmitter causes changes in the neuron
which increase or decrease its likelihood of
"firing," or sending its own signal to other
neurons. Dopamine receptors are located on
corpus striatum neurons, and on nigral cells.
Reduced penetrance: Reduced expression of a
genetic disorder. The term penetrance refers to
the frequency with which a specific genetic
mutation produces its typical effect in those
Reduced penetrance continued
with the genetic abnormality. For example, if
fewer than 100 percent of individuals who
inherit a gene mutation for an autosomal
dominant disorder develop the disease, the
specific trait is said to have "reduced
penetrance."
Reflex: Involuntary, predictable response to a
particular stimulus.
Refractory: Resistant to or not readily yielding
to treatment.
REM sleep: The period of sleep that is
associated with dreaming, rapid eye
movements (REM), and certain involuntary
muscle movements.
Restless legs syndrome (RLS):
A neurologic movement disorder characterized
by unusual, uncomfortable sensations
(paresthesias/dysesthesias) deep within the
calves and/or thighs, resulting in an irresistible
urge to move the legs, and motor restlessness
in response to or in an effort to alleviate
discomfort. In some patients, the arms may
also be affected. Symptoms become obvious or
worse during periods of relaxation or
inactivity; occur most frequently during the
evening or the early part of the night; and may
be temporarily relieved by voluntary
movements of the affected area.
Most patients experience associated sleep
disturbances, including difficulties drifting off
to and remaining asleep. RLS is also often
associated with periodic limb movements of
sleep (PLMS) or repeated, stereotypic, upward
extension of the great toe and foot, potentially
followed by flexion of the knee, hip, or ankle.
Episodes of PLMS typically occur during
periods of lighter (i.e., non-REM) sleep.
Reye syndrome:
A potentially life-threatening disease
characterized by sudden inflammation and
swelling of the brain (acute encephalopathy)
and rapid fat accumulation within certain
internal organs (viscera), particularly the liver,
occurring subsequent to certain viral infections,
such as chickenpox or upper respiratory tract
infections (e.g., influenza B).
Reye syndrome primarily occurs in children and
adolescents, although it has sometimes been
reported during infancy or young adulthood.
About a week after the onset of a viral infection,
patients may develop uncontrollable vomiting,
followed by a rapid onset of listlessness,
confusion, and memory loss, a state of
unconsciousness (coma), seizures, and/or other
findings, potentially leading to life-threatening
complications. Evidence suggests that the use of
aspirin-containing preparations (salicylates) as a
treatment for particular viral infections plays a
role in the development of Reye syndrome.
Therefore, experts advise that such medications
be avoided for the treatment of viral infections
during infancy, childhood, adolescence, and
young adulthood.
Rhythmical myoclonus: Involuntary, shock-like
contractions or spasms of a muscle or muscle
group that occur in a rhythmical pattern. This
usually occurs as a result of a lesion in the
central nervous system.
Rigidity: Stiffness in the limbs or body due to
dysfunction of the basal ganglia and related
structures.
Salicylates:
Medications derived from salicylic acid,
including aspirin (acetylsalicylic acid). Such
compounds have anti-inflammatory, painrelieving (analgesic), and fever-reducing
(antipyretic) activities. Salicylates act to reduce
the production of certain hormone-like
Salicylates continued
chemicals known as prostaglandins that may
have varying actions, potentially leading to
inflammatory effects, increased pain
sensitivity, fever, etc.
Prolonged aspirin use may damage the
stomach or intestinal lining, causing peptic
ulcers and bleeding from the digestive tract. In
addition, excessive intake of salicylates may
lead to salicylate toxicity,
characterized by rapid breathing, irritability,
vomiting, and other findings.
Sandhoff's disease:
A neurodegenerative metabolic disorder that is
characterized by symptoms and findings
similar to those associated with Tay-Sachs
disease as well as possible, moderate
enlargement of the liver and spleen
(hepatosplenomegaly). Sandhoff's disease is a
lysosomal storage disease in which deficiency
of the enzymes hexo-saminidase A and B
results in an abnormal accumulation of certain
fats (i.e., gangliosides) in particular tissues of
the body. The disorder is transmitted as an
autosomal recessive trait and affects only nonJewish individuals (as opposed to Tay-Sachs
disease, which primarily occurs in individuals
of Ashkenazi Jewish ancestry).
Sandifer Syndromrigidity: are dramatic
dystonic postures in children that have been
reported in association with gastroesophageal
reflux. Sandifer syndrome has been associated
with gastroesophageal reflux. GERD is very
common in otherwise asymptomatic infants
but may be associated with apnea, choking,
cyanosis, as well as posturing. The diagnosis is
established by history, ph probe testing, and
disappearance of abnormal postures with
medical management of reflux with posturing
during the testing.
Scoliosis:
Lateral or "sideways" curvature of the normally
vertical line of the spine. Progressive spinal
deformity may be associated with numerous
neuromuscular and neurodevelopmental
disorders (neurogenic scoliosis), such as cerebral
palsy, spinal muscular atrophy, and Rett
syndrome. The severity of the deformity varies,
depending upon the degree of weakness, the
nature and progression of the underlying
disorder, or other factors.
SEP: Somatosensory-evoked potentials use EEG
electrodes to record the response of the brain to
a sensory stimulus. Usually a small electrical
pulse is given at the wrist or behind the knee.
The response in the EEG is then measured. The
pulse needs to be repeated at least several
hundred times
in order to have enough of a signal to analyze.
From this information, the evaluator may
determine whether there is a delay in
conduction to the brain, a blockage at any point,
or abnormally low or high activity in the brain.
SEIZURES: The abnormal electrical discharge of
brain cells (neurons) that results in a transient
disturbance in brain function. Disturbances of
brain function, manifested as episodic
impairment or loss of consciousness, abnormal
movement, or sensory disturbances. Caused by
paroxysmal disturbances in the electrical
activity of the brain.
 Myoclonic: Seizures characterized by
jerking a body extremity or generalized
tonic-clonic seizures within an hour or
two of waking from sleep.
Partial: (Formerly known as focal
seizures.) The seizure is limited to one
area in the brain. During this type of
seizure, the child may experience a
range of strange or unusual sensations
including sudden, jerky movements of
one body part, distortions in hearing or
seeing, stomach discomfort, or a sudden
sense of fear. Partial seizures are
classified as either simple or complex
SEIZURES – Partial continued
In simple partial seizures, there is no
loss of consciousness. In partial
complex seizures, consciousness is
impaired.
 Petit-mal:
Now called generalized absence
seizures. These are characterized by 5
to 15 second lapses in consciousness.
During an absence seizure, the child
appears to be staring into space and
the eyes may roll upwards. Absence
seizures typically occur in childhood
and resolve in adolescence. Absence
seizures are rare in adults.
 status epilepticus:
Seizures that continue for more than 20
minutes without an intervening period of
responsiveness.
Sensorimotor: Pertaining to both the sensory
and motor aspects of a bodily function
serotonin: An important neurotransmitter
(communicates information chemically
between brain cells) that is involved in the pain
disorders and emotional perceptions.
Sequelae: Plural of sequela, which is any
abnormal condition that occurs subsequent to
and/or is caused by disease, injury, or
treatment.
Serotonin (3-[2-aminoethyl]-5-indolol): A
vasoconstrictor found in many tissues of the
body that is present in relatively high
concentrations in portions of the central
nervous system (e.g., hypothalamus, basal
ganglia, etc.). Serotonin functions as a
neurotransmitter, regulating the delivery of
messages between nerve cells (neurons). This
neurotransmitter is thought to play some role
in regulating consciousness and mood states.
Serotonin is also present in other tissues of the
body such as the intestines and blood platelets.
Sialorrhea: Excess production of saliva, or
increased retention of saliva in the mouth, due
to difficulty swallowing.
Side effect: An effect of a drug that is not the
main or intended effect. Side effects may be of
no concern, or they may be bother-some or
even dangerous, in which case they may limit
the upper dose a patient can tolerate. Side
effects are also called adverse effects.
Single photon emission computed
tomography (SPECT): A noninvasive scanning
procedure during which a radioactive
substance known as a radionuclide is
introduced into the body to help evaluate the
function and structure of certain organs or
tissues. The amount of the substance taken up
by particular tissues may depend upon the
amount of blood flow within such regions. For
example, absence of radionuclide uptake in a
targeted region may indicate a lack of blood
flow in certain areas.
Following intravenous administration of the
radioactive compound, a specialized rotating
camera detects the radiation emanating from
the radionuclides in the form of particles
known as protons. The recorded images may
produce colorized, horizontal and vertical cross
sections and be reconstructed by computer to
create three-dimensional images. By evaluating
the blood supply to particular tissues, SPECT
may be particularly helpful in detecting certain
changes within the central nervous system or
the heart.
Spasmodic dysphonia (SD):
A manifestation of dystonia. SD involves the
muscles of the larynx and surrounding muscles
and therefore involves speech. In individuals
with SD, speech in blocked by intermittent
spasms of the voice box (larynx).
Spasmodic torticollis (ST): A form of dystonia
involving the muscles of the neck, and therefore
called "cervical dystonia." As a result of the
abnormal involuntary contractions of the neck
muscles, the head may be rotated, tilted, flexed,
extended, or any combination of these postures.
The movements may be quick, sustained, or
patterned and, therefore, may be associated
with tremor.
Spasmolytic: Antispasmodic; referring to
agents that may eliminate or relieve spasms,
typically of involuntary (i.e., smooth) muscle,
such as within the arteries, the intestine, the
ring-shaped muscles around certain natural
openings or passages (sphincters), the bladder,
the muscular tubes that carry urine from the
kidneys to the bladder (ureters), etc.
Spasticity: stiffness of the body involving the
limbs that results from dysfunction of the
corticospinal tracts. An abnormal increase in
muscle tone that may be caused by certain
types of damage to the nerve pathways
regulating muscles. Spasticity is a common
complication of cerebral palsy, brain injuries,
spinal cord injuries, multiple sclerosis, and
stroke. Spasticity can lead to incoordination,
loss of function, pain, and permanent muscle
shortening, or contracture.
Spinal cord: The cylindrical structure of nerve
tissue that, together with the brain, comprises
the central nervous system. The spinal cord is
an extension of the medulla oblongata--which
is part of the lowest region of the brain
(brainstem)--and is contained within a central
canal in the spinal column.
Sporadically: Occurring intermittently,
randomly, or in isolation.
SSRIs: Selective serotonin reuptake inhibitors.
Drugs belonging to this class are antidepressant
agents that selectively inhibit the absorption of
serotonin at certain nerve membranes (e.g.,
presynaptic neuronal membranes). These drugs
increase the concentration of serotonin within
the central nervous system and enhance
serotonin's neurotransmission activities.
Stereotactic: refers to use of precise coordinates
to identify deep structures of the brain. The
coordinates may be obtained by fitting a
patient's head with a special frame and taking a
CT or MRI scan. The position of the brain
structures relative to the frame permits fine
localization of the deep brain structures.
Stereotactic methods are used during brain
surgery for tremor, Parkinson's disease, and
dystonia. These brain structures are located
with precise, three-dimensional coordinates.
Stereotypic: Inappropriate, persistent repetition
of particular bodily postures, actions, or speech
patterns. These are typically involuntary,
rhythmic, coordinated, and purposeless
movements, postures, or vocalizations that may
appear ritualistic or purposeful in nature.
Stereotypies may be associated with a variety of
neurologic and behavioral disorders, such as
Tourette syndrome, obsessive-compulsive
disorders, Rett syndrome, restless legs
syndrome, schizophrenia, and autism.
Stereotypical: Conforming to a repetitive
pattern as in repetition of particular movements
or gestures.
Stretch reflex: Contraction of a muscle
stimulated by rapid stretching.
Stretch-loop circuits: Pathways of electrical
impulses along specific nerve fibers (alpha
motoneurons) that result in a "stretch" reflex in
a muscle.
Striatum: An area of the brain that controls
movement and balance. It is connected
to and receives signals from the substantia
nigra.
Subarachnoid hemorrhage: Bleeding in the
area surrounding the brain, that is usually a
result of the rupturing of a cerebral aneurysm
in the brain.
Substantia nigra: A dark band of gray matter
deep within the brain where cells manufacture
the neurotransmitter dopamine for movement
control. Degeneration of cells in this region may
lead to a neurologic movement disorder such as
Parkinson's disease.
Sydenham's chorea:
A usually self-limited condition in which
chorea develops in association with an
inflammatory disease caused by certain strains
of streptococci bacteria. This disease, known as
rheumatic fever, is characterized by the sudden
onset of fever and joint pain, with subsequent
inflammation of the heart (carditis), chest pain,
skin rash, and other symptoms. If rheumatic
fever involves the nervous system, Sydenhams
chorea may develop.
This condition commonly affects children aged
5 to 15 or women during pregnancy.
Sydenham's chorea involves involuntary,
uncontrollable, jerky movements that gradually
worsen in severity, potentially affecting arm
movements, the manner of walking (gait), and
speech. In most patients, the condition
spontaneously resolves in weeks or months.
Sympathetic nervous system:
Part of the nervous system that along with the
parasympathetic nervous system forms the
autonomic nervous system (ANS).
The ANS regulates the functioning of
involuntary structures, such as the glands,
smooth muscle, and heart.
The sympathetic nervous system regulates
certain involuntary responses during times of
strong emotion, such as fear or anger; exercise;
or other forms of stress. These responses,
sometimes referred to as the "fright-or-flight
response," include widening of the pupils;
Sympathetic nervous system continued
increased heart and breathing rates;
constriction of most blood vessels, raising blood
pressure; widening of those blood vessels that
supply skeletal muscles; and reduction in the
rate of peristalsis.
Synapse: The junction between two neurons or
between a neuron and an effector organ. As a
nerve impulse reaches a synapse, the terminal
or end of the "presynaptic" neuron's axon
releases neurotransmitters, which diffuse across
the gap and bind to receptors of the "postsynaptic" neuron or the effector organ (i.e.,
muscle or gland). As the electrical impulse is
conducted across the gap, electrical changes are
triggered that serve to continue or
hinder transmission of the impulse.
Synthesis: The formation of a complex
chemical compound through the union of
simpler substances.
Tardive dyskinesia: A movement disorder that
may result from extended therapy with certain
anti-psychotic medications such as haloperidol.
The condition is characterized by involuntary,
rhythmic movements of the face, jaw, mouth,
and tongue, such as lip pursing, chewing
movements, or protrusion of the tongue.
Facial movements are sometimes accompanied
by involuntary, jerky or writhing motions
(choreoathetoid movements) of the trunk, arms,
and legs.
In some patients, symptoms discontinue
months or years after withdrawal of
antipsychotic therapy. However, in others, the
condition may not be reversible.
Tardive dystonia: A form of tardive dyskinesia
characterized by chronic dystonia due to
administration of medications that block
dopamine D2 receptors (dopamine receptor
antagonists), such as certain antipsychotic
agents.
Tardive dystonia continued
(Dopamine receptors are molecules on the
surfaces of receiving nerve cells that are
sensitive to stimulation by dopamine, a
neurotransmitter that controls movement and
balance. Several types of dopamine receptors
have been identified, including D1, D2, and
D3.)
Dystonia is a neurologic movement disorder
characterized by sustained muscle contractions
that often result in repetitive twisting motions
or unusual postures or positions.
Tardive dystonia is the most common form of
secondary dystonia--i.e., dystonia that results
from certain environmental factors or "insults"
that affect the brain. In adults, tardive dystonia
often initially affects facial or neck muscles.
Dystonia may remain limited to such regions or
extend to affect adjacent muscles of the trunk
and arms. Children are more likely to be
affected by generalized dystonia that involves
muscles of the trunk and legs.
Tay-Sachs disease:
A progressive neurodegenerative metabolic
disorder that belongs to a group of diseases
called lysosomal storage diseases. Also known
as GM2 gangliosidosis type I or infantile type,
Tay-Sachs disease results from deficiency of the
enzyme hexo-saminidase A, which leads to an
abnormal accumulation of certain fats (i.e.,
gangliosides) in particular tissues, particularly
nerve cells of the brain. An autosomal recessive
disorder, Tay-Sachs disease primarily affects
individuals of northeastern European Jewish
(Ashkenazi Jewish) ancestry. Symptom onset
typically begins from about 3 to 6 months of
age. Associated symptoms may include an
exaggerated startle response, increasing
listlessness, loss of previously acquired skills
(psychomotor regression), severely
diminished muscle tone (hypotonia), and the
development of characteristic, cherry-red
circular areas within the middle layers of the
eyes (Tay's sign).
Tay-Sachs disease continued
With disease progression, affected infants and
children may develop increasing muscle
stiffness or rigidity; seizures; sudden,
involuntary, "shock-like" contractions of
multiple muscle groups in response to certain
stimuli (generalized, stimuli-sensitive
myoclonus); enlargement of the brain
(metabolic megalencephaly); deafness;
blindness; and dementia. Life-threatening
complications may develop between 2 to 5
years of age.
Tendon: A tough fibrous cord of tissue that
attaches muscle to bone (or other structures of
the body).
Teratogenic: Possessing the ability to disrupt
normal fetal development and causing fetal
abnormalities.
Thalamus: An area of the brain consisting of 2
relatively large masses of gray matter.
The thalamus relays information from most
sensory organs to the outer region of the
cerebrum or cerebral cortex; receives and
processes messages from the body concerning
heat, cold, pain, pressure, and touch; and
influences motor activity of the cerebral cortex.
Tics:
There are motor, vocal, and sensory tics.
These are brief, intermittent stereotyped
movements such as blinking, nose
twitching, head jerking, or transient abnormal
postures. Tics which involvethe respiratory and
vocal apparatus may result in sounds including
sniffs,snorts, grunts, coughs, and sucking
sounds.
HD patients may be unaware of vocal tics, but
family members may find the incessant noises
grating. They should be helped to understand
that the tics are not under voluntary control.
Tics generally do not by themselves require
treatment, but may respond to neuroleptics,
benzodiazepines, or SSRIs.
Tics continued
Tics are involuntary movements, but patients
will usually be able to suppress them
temporarily. They are increased by stress,
excitement, fatigue, and anxiety and decreased
by absorbing activities and sleep; a key feature
is that they wax and wane. The range of tic
manifestations is broad. Motor tics include
abdominal twiddling, fist clinching, foot
dorsiflexion, grimacing, head shaking, head
jerking, hip flexion/abduction, hitting, jumping,
kicking, knee extension, lip protusion, mouth
opening, neck stretching, nose flaring, pelvic
thrusting, platysma contractions, rubbing,
shoulder shrugging, skipping, smelling,
sphincter tightening, spitting, squatting,
stammering, etc Vocal tics include barking,
belching, clicking, coprolalia, coughing,
echolalia, snorting, squeaking etc. There are
two general types of motor tics: myoclonic and
dystonic. In dystonic tics, a posture is briefly
sustained. About 5% of patients with Tourette
syndrome have dystonia. In myoclonic tics, the
movements are very brief, typically clustered
about the face and shoulders.
TMS:
Transcranial magnetic stimulation is a research
technique that uses a magnet to generate a
pulse that goes through the skull and directly
stimulates the brain beneath it. This activates
the fibers controlling muscles, and a surface
EMG electrode may be used to measure the
response in the muscles. Just as stimulating a
nerve may give information about conduction
through the nerve, stimulating the motor areas
of the brain gives information about
conduction from the brain to the spinal cord
and muscles. TMS is currently used only for
research; however, in the future, it may become
a more widely used technique.
Tone: Resistance or tension in a muscle when a
limb or other body part is moved passively and
in a relaxed state about a joint. A state of
muscle tension balanced by partial contraction
or alternate contraction and relaxation.
Torticollis: The involuntary turning of the neck
to one side that can be seen in disorders of the
basal ganglia.
Tourette Syndrome
May be the most dramatic and publicized
manifestation of tics. By definition it is a
chronic syndrome of both motor and vocal tics
that last more than a year according to the DSM
III. It occurs in 1 in 10,000 and mosten in males
with an onset at 2 to 15 years. The syndrome
may be very mild and go untreated throughout
life or may be so severe as to confine the patient
to bed. The patient is able to voluntarily
suppress the movements for minutes or hours
but then experiences an irrestible pressure to
discharge the movements or the vocalizations.
The symptoms may vary over time and remit
spontaneously in one third by late adolescence.
Tourette syndrome is a neuropsychiatric
disorder. Comorbid distrubances include
obsessive-compulsive disorder, attention-deficit
hyperactivity disorder, learning difficulties,
and other behavioral, emotional, or psychiatric
problems, visual and auditory perceptual
abnormalities, language disorders, and sleep
disturbances. Obsessive-compulsive disorder
and ADHD may precede the appearance of tics
and occur in about 50% to 60% of children with
Tourette syndrome. Behavioral or mental
problems may overshadow the tic disorder.
Toxic metabolites: Potentially harmful
substances formed as the result of normal body
functions.
Toxoplasmosis:
A parasitic disease that affects the brain that
occurs in patients who are immunosuppressed
(such as those individuals with AIDS)
Tremor: Rhythmic, involuntary, oscillatory (or
to-and-fro) movements of a body part.
Tropical spastic paraparesis (HTLV-1associated myelopathy): A rare disorder
characterized by slowly progressive weakness
(paraparesis), stiffness (rigidity), and spasticity
of the leg muscles due to infection with the
human T-cell lymphotropic virus-1 (HTLV-1).
Modes of transmission include sexual contact,
mother-to-child transmission (e.g., via
breastfeeding), and blood transfusion.
Truncal ataxia (gait/walk)
Patients with truncal ataxia caused by damage
to the cerebellar vermis orassociated pathways
tend to have a wide-based, unsteady gait, and
become more unsteady when attempting to
keep their feet close together.
Unilateral: Affecting, pertaining to, or confined
to one side only.
Unverricht-Lundborg's disease
(Baltic myoclonic epilepsy): A form of
progressive myoclonic encephalopathy (PME)
characterized by the development of repeated
seizures or episodes of uncontrolled electrical
activity of the brain (epilepsy); sudden, "shocklike" muscle contractions that may be induced
by voluntary movements or in response to
certain external stimuli (action or reflex
myoclonus); and eventual impairment of
coordination, postural instability, and other
associated findings (i.e., cerebellar ataxia).
Although mental deterioration may also be
associated with the disorder, it is typically
milder than that seen with Lafora's disease
(another form of PME). Unverricht-Lundborg's
disease is thought to be inherited as an
autosomal recessive trait. Symptom onset
typically begins from about age 6 to 13.
The disorder is slowly progressive;
however, the degree of disease progression and
disability may be extremely variable among
affected family members.
Upper motor neurons: Nerve cells extending
from the brain to the spinal cord that control
movement.
Variable expressivity:
Varying manifestation of a genetic trait. The
term "expressivity" refers to the degree to
which a hereditary trait appears in
an individual. Thus, in individuals with a gene
mutation for an autosomal dominant disorder
that has variable expressivity, the specific
characteristics that are manifested may vary in
range and degree from mild to severe.
Vascular: Pertaining to or containing blood
vessels.
Vasomotor: Pertaining to the muscles and
nerves that control blood vessel diameter,
thereby regulating or modulating blood
pressure.
Ventral intermediate (VIM) nucleus:
A specific region of the thalamus. This area of
the brain is involved in the control of
movement and is the "target" area for
thalamotomy and deep brain stimulation when
treating patients with tremor.
VEP:
Visual-evoked potentials - are similar to
somatosensory potentials; however, the
stimulation is applied as patterns or flashes of
light seen by the eye, and the brain's response
to the visual stimulus is then assessed with
EEG electrodes.
Virulent:
Referring to or characterized by virulence or
the degree to which an invading
microorganism, such as a bacterium or virus, is
able to produce disease. Measures of virulence
may be based upon the micro-organism's
ability to invade bodily tissues and the severity
of the disease produced.
White matter: The lipid rich myelinated portion
of the brain and spinal cord.
Wilson disease:
(Often ruled out first when testing a patient for
a neurological disease of "unknown origin"
such as HD.) A rare genetic disorder of copper
metabolism, leading to an excessive accumulation of copper in certain tissues and organs,
including the liver, brain, kidneys, or corneas of
the eyes. Without prompt, appropriate
treatment, the disorder may result in
progressive liver disease, degenerative changes
of the brain, psychiatric abnormalities, and
other symptoms. Neurologic findings may
include tremor; involuntary, rapid, jerky
movements combined with relatively slow,
writhing movements (choreoathetosis);
impaired muscle tone and sustained muscle
contractions, producing repetitive movements
and abnormal posturing; increasingly slurred
speech; and difficulties swallowing. Some
patients may also experience increasing
irritability, anxiety, severe depression, unusual
behaviors, or other psychiatric problems.
X-linked dominant trait: Human traits, such as
an individual's specific blood group, eye color,
or expression of certain diseases, result from
the interaction of one gene inherited from the
mother and one from the father. In X-linked
dominant disorders, the gene mutation for the
disease trait is transmitted as a dominant gene
on the X chromosome and therefore may
"override" the instructions of the normal gene
on the other chromosome, resulting in
expression of the disease. Because females have
two X chromosomes yet only one functioning
copy is necessary, a percentage of X chromosomes with the mutated gene may not be
expressed (random X chromosome
inactivation). As a result, females often have
less severe symptoms than affected males. In
contrast, because males have one X chromosome from the mother and one Y chromosome
from the father, those who inherit an X-linked
dominant disease trait typically fully express
the mutated gene on the X chromosome,
causing a more severe form of the disorder that
may result in lethality before or shortly after
birth.