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“ЗАТВЕРДЖЕНО”
на методичній нараді кафедри
нервових хвороб, психіатрії
та медичної психології
“______” _______________ 2008 р.
Протокол № _____
Зав. кафедри нервових хвороб, психіатрії
та медичної психології
професор
В.М. Пашковський
METHODOLOGICAL INSTRUCTION №5
THEME: Sensory system. Syndromes of it’s lesion. Method of research of
sensation.
Modul 1. General neurology
Сontents modul 1. introduction. symptoms of motor and sensory disturbanses
Subject:
Nervous deseases
Year 4
Medical faculty
Hours 2
Author of methodological instructions
PhD, MD Zhukovskyi O.O.
Chernivtsy 2008
1. Scientific and methodological substantiation of the theme. Different specialists
meet with disturbance of sensation in case of many different diseases, such as lues,
diabetes mellitus, stroke, polyneuritis, radiculopathyes. That’s way knowledge of
sensation disturbance signs has the large value for rendering a well-timed medical
care to the patient and solution of questions of a working capacity.
2. Aim: students should be able to determine independently disturbance of
sensation in the patients and made topical diagnosis.
Students must know:
1.
Anatomy of spinal cord.
2.
Anatomy of superficial sensory explorers.
3.
Anatomy of deep sensory explorers.
4.
Examination of sensation.
5.
Classification of sensation.
6.
Types and sorts of sensory disturbances.
Students should be able to:
1. Collect the patient’s complaints (tingling, creeping, burning and numbness
sensation) and to analyze them.
2. Examine patient’s neurological status.
3. Make a conclusion about the focus of lesion.
4. Point character of sensory disturbance.
Student should gain practical skills:
1. To check superficial (pain, temperature, tactile) sensation
2. To check deep (joint sense, vibration sense, feeling of pressure, feeling of mass,
kinesthesia) sensation
3. To check complicated sensation (stereognosis, graphism, localization sense,
discrimination sense)
4. To examine different types of sensory disturbances:
- peripheral
- segmental
- conductive
5. Make a conclusion about the focus of lesion
3. Educational aim. To indicate that the somatic sensory system contains three
primary components: receptor organs, sensory pathways and brain centers. Sensory
systems have both a hierarchical and parallel organisation. In general, somatic
sensory systems consist of a three-neuron projection system.
4. Integration (basic level).
Subjects
Anatomy
Histology
Physiology
Gained skills
Knowledge of anatomy of the brain and spinal
cord.
Knowledge of anatomy of sensory explorers.
Knowledge of anatomic structures of analyzers
and receptor apparatus.
Hystological structure of analyzers and receptor
apparatus
Knowledge of function of the brain and spinal
cord.
Knowledge of physiologic function of sensory
explorers.
Knowledge of physiologic function of analyzers
and receptor apparatus.
Subject. The somatic sensory system contains three primary components:
receptor organs, sensory pathways and brain centers. Sensory systems have both a
hierarchical and parallel organisation. Hierarchical organisation means that sensory
information is transmitted sequentially via several orders of neurons located in relay
nuclei and is processed at each relay station under the control of higher stations in the
system. Parallel organisation means that individual modalities are served by separate,
parallel system and that a given sensory modality, like touch, can be transmitted be
more than one system at the same time.
In general, somatic sensory systems consist of a three-neuron projection
system.
Pathway for Tactile Discrimination and Arm Proprioception (Dorsal
Column-Medial Lemniscal Pathway). Tactile discrimination (touch and vibration
sense) is subserved by low threshold mechanoreceptors located in the skin (hair cells,
Merkel’s receptors, Meissner’s, Ruffini’s, and pacinian corpuscles), and limb
proprioception is subserved by low threshold mechanoreceptors located in joints,
tendons, and muscles. The cell-bodies of first-order neurons are located in dorsal root
ganglia, with distal axons projecting from mechanoreceptors and proximal axons
projecting into the spinal cord via the medial division of the dorsal root entry zone.
After entry, the first-order neurons ascend uninterrupted in the ipsilateral dorsal
columns to the brain stem. The dorsal columns also contain a smoller percentage of
axons from second-order neurons that originated in laminae III and IV of the dorsal
horn. The dorsal columns are located in the posterior funiculus and consist of the
fasciculus gracilis and fasciculus cuneatus. The fasciculus gracilis lies adjacent to the
posterior medial septum and contains fibers from the ipsilateral sacral, lumbar, and
lower thoracic segments. The fasciculus cuneatus includes fibers from the upper
thoracic and cervical segments. It exists only from T6 and above, where it is located
lateral to the fasciculus gracilis in the posterior funiculus. The cell bodies of secondorder neurons are located in nucleus gracilis and nucleus cuneatus in the base of the
medulla. The axons of second-order neurons cross the midline (decussate) and project
to the ventral posterolateral nucleus (VPL) of the contralateral thalamus via the
medial lemniscus. Third-order neurons project from the thalamus to the primary
sensory cortex via the posterior limb of the internal capsule. The axons of third-order
neurons project to the primary somatosensory cortex located in the postcentral gyrus
(areas 3, 1, 2 of Brodmann) of the parietal lobe.
Pathway for Pain and Temperature (Lateral Spinothalamic Tract).
Information about pain and temperature from the opposite side of the body is
transmitted in the anterolateral system. The anterolateral system also carries tactile
and proprioceptive information. The proximal axon of first-order neurons enters the
spinal cord in the intermediate division of the dorsal root entry zone and joins with a
tract of Lissauer. Fibers from the tract of Lissauer divide into short ascending and
descending branches (one or two levels from the level of entry) and synapse with
second-order neurons located in the ipsilateral dorsal horn (lamine I and V). Axons of
second-order neurons cross the midline in the anterior grey and white comissures and
ascend as the neospinothalamic tract, which synapses on third-order neurons located
in the VPL of the thalamus. Axons of third-order neurons project to the primary
sensory cortex. Throughout the entire three-neuron projection system, somatic
sensory systems maintain a somatotopic organisation such that the surface of the
body is represented in a topographic fashion in the pathways, relay nuclei, and the
primary sensory cortex.
Types of sensory disturbances:
1. Peripheral.
2. Spinal
3. Cerebral
The peripheral type arises at lesion of dendrites of the first neuron of all sorts
of sensation.
Peripheral type is divided on:
mononeuritic (or neural pattern) – is observed at lesion of one
peripheral nerve and consist of disturbance of all sorts of sensation in innervative
zone of this nerve. There is a pain in the field of nerve, sometimes hyperpathia,
hyperalgesia, tension signs of nerve, pain at palpation;
polyneuritic pattern – is observed at multiple, frequently symmetric
lesion of all peripheral nerves. Appears by sensory disturbance in distal parts of
extremities as “socks” on legs and “gloves” on arms. The “socking-glove” pattern of
sensory loss is typical for peripheral neuropathy. But sometimes cerebral or spinal
lesion may cause distal sensory loss, usually of a single extremity in the case of
cerebral disease, and often in association with hyperreflexia and the Babinski sign in
cases of either cerebral or spinal lesions;
plexus pattern – arises at lesion of dorsal root ganglia and appears by
sensation disturbance in innervative zone a plexus. In this case there are pains,
tension signs of nerves going from a plexus, movement’s disturbance – peripheral
paresis of muscles group, which innervated from this plexus.
Spinal type is divided on:
segmental-radicular pattern occurs at a lesion of dorsal root or
simultaneous lesion of root and dorsal root sensitive ganglion. At lesion of dorsal root
there is a loss of all sorts of sensation in its zone innervation according to the
segmental type. The sensitive disturbance is appeared as transversal strip on a trunk
and longitudinal strip on extremities (in human being there are 36 sensitive
segments). This type of disturbance of sensation arises at radiculopathyes, at
extramedular tumors. At lesion of dorsal root ganglion occur herpes exanthema in
zone innervation of the struck segment (at a ganglionitis or ganglioneuritis) as
bubbles (so-called herpes zoster), sharp pains and anesthesia in a segment;
segmental-dissociated pattern. It is observed at lesion of dorsal horns
of spinal cord and front gray soldering. Thus the disturbance of sensation appear as
loss or lowering pain and thermoanesthesia and saving tactile and joint sense in given
segment. Such disturbance are called dissociated and result from that in dorsal horns
and front gray soldering pass explorers of superficial sensation, and from the
explorers of deep feeling that do not go to a dorsal horn of spinal cord (recollect
anatomy). The dissociated type of disturbance of sensitivity more often arises at
myelosyringosis, when the sensitive disturbance are observed in certain dermatomes
as “jacket” or “half jacket” at lesion of dorsal horns of spinal cord in thoracic
segments, or “trousers” - at lesion of dorsal horns of spinal cord in lumbar segments;
conductive type. There are complaints on a loss of pain and
temperature sensation below the level. Objective: it occurs at lesion of sensation
explorers that are in spinal-thalamic tract, Holl’ and Burdach’ pathways in spinal
cord. This type can be:
a) compete transversal (it is observed at lesion of a diameter of a spinal cord, at
which all sorts of sensation drop out below the level of lesion, and pain and
temperature sensation - 1-2 segments below the level of lesion, and deep - from the
same level)
b) half transversal or Brown-Sequard occurs at a lesion of half of diameter of a
spinal cord, thus the deep feeling drops out on the side of a defeat, and pain and
temperature - on the opposite side, 1-2 segments lower.
Cerebral type is divided on:
conductive subtype occurs at lesion of bulbothalamic tract, medial
closed loop and thalamocortical tract in brain.
alternating (brain stem). At a lesion of sensitive fibbers in a brain stem
there is a fallout of sensation on the face according to the segmental type on the side
of lesion both pain sensation and thermoesthesia on a trunk and extremities on the
opposite the sides.
Cortical subtype occurs at lesion of postcentral gyrus and upper
parietal gyrus. Thus the sensation drops out according to a monotype either in arm or
in leg, or in face depending on localization of lesion in the postcentral gyrus. At
irritation of a dorsal central gyrus paresthesia on the opposite side on face, in arm or
in leg occurs.
Self assessment:
1. Subjective sorts of sensory disturbances.
2. Sorts of pain.
3. Objective sorts of sensory disturbances.
4. Types of sensory disturbances.
5. Subtypes of peripheral sensory disturbances.
6. Subtypes of segmental sensory disturbances.
7. Subtypes of conductive sensory disturbances.
8. What nervous structures are damaged in case of peripheral type of sensory
disturbances?
9. What nervous structures are damaged in case of segmental-dissociated
subtypes of sensory disturbances?
10.What nervous structures are damaged in case of by segmental-radicular of
sensory disturbances?
11.What nervous structures are damaged in case of conductive type of sensory
disturbances?
12.Where are the cells bodies of a) the first neuron; b) the second neuron situated?
13.What are specific methods of reactive pain examination?
14.Where are the cell bodies of neurons of superficial and deep sensation situated
together?
15.Sorts of superficial sensation.
16.Sorts of deep sensation.
17.Combined sorts of sensation.
18.What segment is on belly-button’s level?
19.What segment is on collar’s level?
20.What segment is on nipple of men level?
21.What segment is on inguinal level?
22.What nervous form the pathway of superficial sensation?
23.What nervous form the pathway of deep sensation?
24.Name the proprioreceptors.
25.How sensation is divided according to biological classification?
1.
a)
b)
c)
d)
e)
Tests
What structures give the beginning to the spinothalamic tract
Dorsal horn;
Ventral horn;
Lateral horn;
Hall’s nucleus;
thalamus.
2.
a)
b)
c)
d)
e)
What kind of anesthesia occurs with complete lesion of peripheral nerve?
Pain and temperature;
All kinds of sensation;
Tactile and pain;
Joint and pain;
Vibration and pain.
3.
a)
b)
c)
d)
e)
Where is the second neuron of deep sensation situated?
In dorsal horn of the spinal cord;
In lateral horn of the spinal cord;
In n. thalami;
In postcentral gyrus;
In Holl’s and Burdach’s nuclei.
Real-life situations:
1. There is a bathyanesthesia in legs, including hip joints in patient. What
pathways are damaged?
2. There is lesion of spinothalamic tract on Th5 level on right in patient. What
sort and type of sensory disturbance is present?
3. The patient suffers a lack of superficial sensation in distal parts of
extremities. What type of sensory disturbance is present?
References:
1.
Basic Neurology. Second Edition. John Gilroy, M.D. Pergamon press.
McGraw Hill international editions, medical series. – 1990.
2.
Clinical examinations in neurology /Mayo clinic and Mayo foundation. – 4th
edition. –W.B.Saunders Company, Philadelphia, London, Toronto. – 1976.
3.
McKeough, D.Michael. The coloring review of neuroscience /D.Michael
McKeough/ - 2nd ed. – 1995.
4.
Neurology for the house officer. – 3th edition. – howard L.Weiner, MD and
Lawrence P. Levitt, MD, - Williams&Wilkins. – Baltimore. – London. –
1980.
5.
Neurology in lectures. Shkrobot S.I., Hara I.I. Ternopil. – 2008.
6.
Van Allen’s Pictorial Manual of Neurologic Tests. – Robert L. Rodnitzky. 3th edition. – Year Book Medical Publishers, inc. Chicago London Boca
Raton. - 1981.