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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 № 6
THEME: SORTS AND TYPES OF SENSORY DISTURBANCES
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
MD, Filipets 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, types of sensory disturbance, level of localization of the
pathological process (focus), to formulate and to explain the topical diagnosis.
Students must know:
1.
Anatomy of brain and 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.
7.
Semiology of sensory explorers on different level.
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.
Make a topical diagnosis.
5.
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. Symptoms produced by lesions of the dorsal column-medial
lemniscal pathway are manifest primarily as defects in joint position sense and
stereognosis. Diffuse involvement of large-diameter neurons causes loss tactile
discrimination and inability to detect joint position and vibration, which produces
extreme difficulty in manipulating objects without visual guidance. These lesions also
cause loss of muscle coordination and severe disturbances of locomotion because of
loss of proprioception (sensory ataxia). The dorsal column system provides fast,
accurate feedback about movement, and coordinated motor output suffers from
lesions at any level of this system.
Because of redundancy and parallel pathways for transmission of tactile and
proprioceptive information, central lesions of the dorsal column system produce less
severe or partial abnormalities. Because the system is uncrossed until the medulla,
lesions in the peripheral or spinal levels, up to and including the nuclei, produce
symptoms on the side of the lesion. Lesions of the medial lemniscus, thalamus, or
sensory cortex will produce similar symptoms but on the side opposite the lesion.
Symptoms produced by lesions of the anterolateral system vary according to
the level of the neuraxis involved. Lesions outside the nervous system frequently
stimulate adjacent free nerve endings, thereby producing the subjective sensation of
pain. This symptom is most important in calling attention to pathological processes
occurring in internal organs, most of which contain no pain receptors of their own.
Lesions that involve the peripheral level may cause either the sensation of pain when
involving nonneural tissue or the loss of pain and temperature sensibility in the area
subserved by the affected nerves. Lesions of the central nervous system that involve
the anterolateral system result in an inability to perceive pain or discriminate hot from
cold on the contralateral side of the body below the level of the lesion. At the level of
the brain stem, lesions produce loss of pain and temperature sensibility in the
contralateral body and ipsilateral face. A lesion that affects the ventral posterior
thalamic nucleus causes a complete loss of all general somatic sensory information
from the contralateral face, trunk, and limbs. Thalamic lesions sometimes produce a
severe burning pain in the area of sensory loss.
The differences in the functional organization of the dorsal column-medial
lemniscal and anterolateral systems are highlighted by the sensory symptoms that
follow a hemisection of the spinal cord. Tactile discrimination and limb
proprioception, which are relayed by the dorsal columns, are lost in the ipsilateral
arm and leg, whereas pain and temperature sense, which are relayed by the
anterolateral system, are lost in the contralateral arm and leg.
The primary somatic sensory cortex plays an important role in processing all of
the submodalities of the sensory system. It is located in the anterior region of the
parietal lobe (postcentral gyrus) and consist of four anatomically distinct areas (1, 2,
3a, and 3b of Brodmann). Area 1 receives input from rapidly adapting receptors in
the skin, area 2 receives input from the pressure and joint position receptors in deep
tissue, area 3a receives input from muscle spindles, and area 3b receives input from
rapidly and slowly adapting receptors in the skin. Each area contains a unique
topographic representation. The input to the primary sensory cortex comes from the
opposite side of the body and projects via the ventral posterior tier of the thalamus.
Output from the primary motor cortex goes to several places: the contralateral
primary sensory cortex; the contralateral dorsal column-medial lemniscal system and
ipsilateral ventral posterior lateral thalamus to control input; the ipsilateral motor
cortex and basal ganglia for motor control; and the secondary somatic sensory cortex.
The secondary somatic sensory cortex is located on the superior bank of the
lateral sulcus. Tertiary somatic sensory cortex is located in the insula (at the base of
the lateral fissure) and posterior parietal lobe. These regions integrate somatic
sensory information with other information (e.g., visual and memory) to form
complex abstract perceptions.
Lesions of the parietal lobe, seen commonly in cerebrovascular accidents
involving the middle cerebral artery, affect the primary, secondary, and tertiary
somatic sensory cortices. Cortical lesions alter all somatic sensory information from
the opposite side of the body. Unlike thalamic lesions that produce severe disruption
of all sensory modalities, cortical lesions produce only minimal disruption of
primitive sensory discrimination involving pain, temperature, touch, and vibration but
severe deficits in joint position sense, two-point discrimination, touch localization,
and the ability to recognize objects placed in the hand (astereognosis). This pattern of
loss is referred to as cortical sensory deficit. Primitive perception is formed in the
thalamus and thus remains after cortical lesion; localization and discrimination are
performed by the cortex and are thus severely diminished after cortical lesion.
Self assessment:
Tests for self-assessment:
1. Signs of irritation of the lower parts of post central gyruses of dominant
hemisphere.
2. Signs of irritation of the middle parts of post central gyruses of dominant
hemisphere.
3. Signs of irritation of the upper parts of post central gyruses of dominant
hemisphere.
4. Signs of lesion of the radiate crown (corona radiata) on the right side.
5. Signs of lesion of the dorsal leg of internal capsule.
6. Signs of lesion of right thalamus.
7. Signs of lesion of right medial closed loop.
8. Signs of lesion of Burdach’s pathways in spinal cord.
9. Signs of lesion of Holl’ pathways in spinal cord.
10.Signs of lesion of dorsal root.
11.Signs of lesion of dorsal horn in spinal cord.
12.Signs of lesion of dorsal root ganglion.
13.Signs of lesion of front and dorsal roots.
14.Signs of lesion of lateral funicular of spinal cord on right Th10.
Tests
1. What type of sensory disturbance occurs when medial lemniscus is damaged?
a) conductive;
b) cortical;
c) segmental;
d) polyneuritic;
e) radicular.
2. Lesion of what kind of sensation occurs when dorsal horn is damaged?
a) All kinds of sensation;
b) Complicated sensation;
c) Superficial sensation;
d) Deep sensation;
e) Special sensation.
3. What type of sensory disturbance occurs when front white soldering is
damaged?
a) conductive;
b) cortical;
c) segmental;
d) polyneuritic;
e) radicular.
Real-life situations:
1.
There are analgesiya and termoanesthesia along segments C5-Th5 on
both sides in patient. Where is pathological focus?
2.
There is a lesion of dorsal funiculus on Th7 level on left in patient. What
sort and type of sensory disturbance is present?
3.
The patient has half-transversal lesion of the spinal cord on level Th5 on
the right. What sort and type of sensory disturbance is present? What is the name of
this pattern?
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.