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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.