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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 № 10
THEME: PATHOLOGY OF IX-XII NERVES. BULBAR AND PSEUDOBULBAR
SYNDROMES. METHODS OF EXAMINATION
Modul 1. General neurology
Сontents modul 2. Pathology of the cranial nerves. The disorders of the autonomic nervous
system and brain cortex functions. Meningeal syndrome. The additional methods of
examination in neurology.
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.
Examination of cranial nerves is essential to a complete study of the nerves system.
In order to localize lesions within the brain stem one must know the location and
function of the pathways and nuclei. The IX, X, XI, XII nerves’ lesions may result
from any type of disease: vascular, neoplastic, inflammatory.
2. Aim: students should be able to find out symptoms of nerves lesions, to
localize the pathological processes.
Students must know:
1. Symptoms of IX, X, XI, XII nerves lesion.
2. Alternating syndromes of the medulla oblongata (Jackson’s, Aweli’s,
Schmidt’s, Valenberg-Zakcharchenko’).
Students should be able to:
1.
Localize processes within certain anatomic structures of medulla
oblongata.
2.
Put topical diagnosis and to explain it.
1.
2.
3.
4.
5.
6.
Student should gain practical skills:
To examine Glossopharyngeal nerve.
To examine Vagus nerve.
To examine the Accessory nerve.
To examine Hypoglossal nerve.
To find bulbar and pseudobulbar paralysis
Make a conclusion about the focus of lesion and make a topical diagnosis.
4. Integration (basic level).
Subjects
Anatomy
Gained skills
Knowledge of anatomy of medulla oblongata.
Knowledge of anatomy of IX, X, XI, XII nerves.
Histology
Hystological structure of the anatomy of medulla
oblongata, IX, X, XI, XII nerves and their
pathways
Physiology
Knowledge of function of medulla oblongata,
IX, X, XI, XII nerves.
Subject
The medulla (medulla oblongata or bulb) is the rostral extension of the spinal
cord beyond the foramen magnum and extends to the caudal segment of the pons.
The ascending and descending pathways of the spinal cord pass through the medulla.
The spinothalamic tracts pass directly through almost unchanged but it is in the
medulla that the corticospinal fibers and the dorsal columns of the spinal cord cross
the midline. The medulla also contains the nuclei of several cranial nerves, parts of
the vestibular and olivary nuclear complexes, and the inferior cerebellar peduncle.
The majority of the reticular formation, including the centers that control heart rate,
blood pressure, respiration, and arousal, are located in the medulla.
Glossopharyngeal Nerve (IX)
The glossopharyngeal nerve contains fibers from five different functional
categories. The cell bodies of GSA fibers are located in the superior ganglion of IX,
with distal processes that innervate pain and temperature receptors in the external
auditory meatus and skin over the ear. The proximal processes terminate in the
nucleus of the spinal tract of the trigeminal nerve. The cell bodies of GVA fibers are
located in the inferior (petrosal) ganglion, with distal processes that carry general
sensory input (not taste) from the posterior third of the tongue and the pharynx. A
special branch of these fibers innervates the carotid sinus (pressor receptors and
arterial pressure receptors) and the carotid body (chemoreceptors, CO2, and O2
concentration in the blood). Most of the central processes terminate in the caudal part
of the nucleus of the solitary tract. Other cell bodies in the inferior ganglion have
peripheral processes that innervate taste buds on the posterior third of the tongue.
Central processes of these SVA fibers terminate in the rostral portion of the nucleus
of the solitary tract. SVE fibers with cell bodies in the nucleus ambiguus innervate
the muscles that affect swallowing (pharyngeal and palatine muscles) and the muscle
that elevates the upper pharynx (stylopharyngeus). This is the only skeletal muscle of
the third branchial arch. Preganglionic parasympathetic (GVE) fibers from the
inferior salivatory nucleus terminate in the otic ganglion. Postganglionic fibers
innervate the parotid gland.
Clinical Aspects. The glossopharyngeal nerve is tested by asking the client to
say "ah" and watching to see that the soft palate moves or by using a tongue blade to
produce a gag reflex.
Lesion of the glossopharyngeal nerve produces the following symptoms: loss
of sensation, including taste, from the posterior third of the tongue; loss of gag,
palatal, uvular, and carotid reflexes; difficulty in swallowing (dysphagia); and
deviation of the palate and uvula to the normal side.
Clinical examination the ninth nerve (Glossopharyngeal nerve) is tested by
touching the posterior wall of the pharynx with a wooden tongue depressor or
applicator stick. The normal response is prompt contraction of the pharyngeal
muscles, with or without gagging. However, the finding of a normal gag reflex after
intracranial section of the ninth nerve suggests that the posterior pharyngeal wall is
also supplied by the tenth cranial nerve. The testing of the taste sensation on the
posterior one third of the tongue is technically too difficult to be of much clinical
value.
Vagus Nerve (X)
The vagus contains fibers from five different functional categories. The cell
bodies of GSA fibers are located in the superior (jugular) ganglion of X and distal
processes conveying touch, pain, and temperature information from the skin of the
auricle. The central processes of these neurons terminate in the spinal nucleus of V.
The cell bodies of GVA fibers are located in the inferior (nodose) ganglion and distal
processes convey general sensory information from the respiratory system (pharynx,
larynx, trachea, and lungs), cardiovascular system (carotid body and sinus, heart, and
various blood vessels), gastrointestinal tract, and dura mater in the posterior fossa.
The proximal processes of these neurons terminate in the nucleus solitarius. The SVA
fibers mediate taste. Their cell bodies are located in the inferior ganglion; distal
processes innervate taste buds in the epiglottis via the internal laryngeal nerve.
Central processes of these neurons also terminate in the nucleus solitarius. The GVE
component consists of preganglionic parasympathetic fibers from the dorsal vagal
nucleus that terminate on postganglionic neurons in the wall of the thoracic and
abdominal viscera. Postganglionic fibers extend to cardiovascular, respiratory, and
gastrointestinal organs, where they innervate glands, and cardiac and smooth muscle.
The SVE output is by lower motor neurons from the nucleus ambiguus that innervate
the voluntary muscles of the soft palate, pharynx, and intrinsic laryngeal muscles.
Clinical Aspects The vagus nerve can be tested with the glossopharyngeal
while producing a gag reflex or by asking the client to cough.
A complete unilateral lesion of the vagus nerve produces the following symptoms:
flaccid soft palate, which produces a voice with a twang; difficulty in swallowing
(dysphagia); a weak cough; and transient tachycardia. Bilateral lesions of the vagus
nerve are usually fatal due to laryngeal paralysis.
Spinal Accessory Nerve (XI)
The accessory nerve contains two roots: bulbar (cranial) and spinal. Both roots
contain SVE fibers. The cervical root has cell bodies located in the nucleus ambiguus
and fibers accompanying the vagus nerve form the recurrent laryngeal nerve, which
innervates the intrinsic laryngeal muscles. Fibers in the spinal root originate from
anterior horn cells in segments CI through C5 (spinal accessory nucleus). After
exiting the spinal cord, fibers ascend on the lateral surface of the cord, pass rostrally
through the foramen magnum, join with the cranial root in the jugular foramen, exit
the skull with nerves IX and X, and innervate the ipsilateral sternocleidomastoid and
upper trapezius muscles.
Clinical Aspects The accessory nerve is tested with a manual muscle test of
head rotation (sternocleidomastoid) and shoulder shrug (upper trapezius).
Unilateral lesion of the cranial root (or recurrent laryngeal nerve) produces the
following symptoms: The ipsilateral vocal cord becomes fixed and partially adducted, and the voice is hoarse (dysphonia) and reduced to a whisper. Unilateral
lesion of the spinal root produces the following symptoms: flaccid paralysis of the
sternocleidomastoid with inability to rotate the head to the side opposite the lesion
and flaccid paralysis of the upper trapezius with a downward and outward rotation of
the scapula.
Hypoglossal Nerve (XII)
Lower motor neurons in the hypoglossal nerve have their cell bodies located in
the hypoglossal nucleus in the brain stem and innervate the muscles of the ipsilateral
tongue (genioglossus, styloglossus, and hypoglossus). The nerve also contains
proprioceptive fibers from the Ungual musculature (GSA), thought to arise from
scattered neurons that have been found along the nerve.
Lesion of the hypoglossal nerve produces an ipsilateral lower motor paralysis
of the tongue. Early fibrillations are replaced by muscle atrophy and wrinkling on the
side of the lesion. When protruded, the tongue deviates to the paralyzed side.
The gustatory (taste) system originates from receptors in the oral cavity,
projects directly into the brain stem, and ascends as far as the cerebral cortex in the
parietal lobe. Gustatory receptors transduce soluble chemical stimuli into electrical
signals that are perceived by the brain as basic taste categories. In conjunction with
the olfactory and somatic sensory systems, the gustatory system provides
information about the taste of food. This information is used to determine which
substances are eaten and, therefore, has obvious survival value.
The word "taste" is generally used synonymously with "flavor," which is a
subjective perception based on information from several sensory modalities. Vision
and olfaction, along with temperature and tactile senses, play a large part in
determining the taste of a substance. Four taste modalities are recognized in
humans: salt, sweet, sour, and bitter. Many taste sensations, such as those from
numerous spices, fruits, and vegetables, are impossible to describe using the four
"elementary taste categories." In fact, an objective schema for classifying all tastes
does not exist. The four elementary taste modalities are probably indicative of how
little is clearly understood about this complex sensory modality. However, it seems
clear that taste is basically a chemically induced sense.
Receptor Anatomy and Physiology. Gustatory receptors are epithelial taste
buds that line the papillae of the tongue, palate, and pharynx. Papillae are ridges of
tissue that can be readily seen on the edges of the superior surface of the tongue.
Taste buds consist of a cup-like configuration of epithelial cells, with tiny hair cells
(microvilli) that project into the taste pores lining the sides of the central canal of the
papillae. There are three types of papillae in humans: Fungiform papillae are located
on the anterior two thirds of the tongue, circumvallate papillae are found on the
posterior third of the tongue, and foliate papillae are located on the posterior edge of
the tongue. Taste buds found on the palate, epiglottis, and esophagus are not located
in papillae.
Individual taste buds consist of three types of cells: nonneural support cells
that provide structure for the receptor; basal cells located at the base of the taste bud
that act as transition cells, eventually differentiating to become receptor cells; and
between 50 and 150 receptor cells. Taste buds are embedded in the epithelium of the
papilla and open to the surface with the taste pore, which is lined with microvilli
that extend from the apical surface of each receptor cell. The microvilli are thought to
be the sites at which sensory transduction occurs. All substances must be water soluble
to activate the receptor; however, the exact mechanism by which the receptor
transduces particular chemicals into nerve impulses remains unknown.
The life expectancy of receptor cells is only from three to five days. As
individual cells die, they are replaced by maturing basal cells. The replacement process takes approximately 10 days. The rate of replacement slows progressively
throughout life such that in the later decades of life, taste acuity or sensitivity of taste
is significantly diminished.
Each taste bud contains approximately 50 receptor cells. Different receptor cells
apparently have receptors specific for different chemicals, but the mechanisms of the
interactions are not well understood. Each taste bud contains several different types
of receptor cells and can respond to several stimuli. The combination of receptor types
varies from bud to bud. Distinct receptor cells detect four basic taste qualities:
sweet, salt, sour, and bitter. These receptors are distributed such that the tip of the
tongue is most responsive to sweet stimuli, the anterior lateral margins to salty, the
entire lateral margin to sour, and the back of the tongue to bitter.
Central Pathway. Each receptor cell is innervated at its base by the peripheral
process of a first-order neuron. Each peripheral process branches repeatedly,
innervating several papillae, several taste buds within each papilla, and several
receptor cells within each taste bud. Thus, the information transmitted by a single
afferent fiber represents the input from many receptor cells. Receptor cells form
chemical synapses with first-order neurons.
Taste buds located in the anterior two thirds of the tongue are innervated by
first-order neurons that travel in the chorda tympani branch of the facial nerve (CN
VII) with cell bodies located in the geniculate ganglion. Taste buds in the posterior
third of the tongue are innervated by first-order neurons that travel in the lingual
branch of the glossopharyngeal nerve (CN IX) with cell bodies in the petrosal
ganglion. The taste buds on the palate are innervated by first-order neurons that
travel in the greater superficial petrosal branch of the facial nerve. The taste buds on
the epiglottis and esophagus are innervated by first-order neurons that travel in the
superior lingual branch of the vagus nerve (CN X) with cell bodies in the nodose
ganglion.
The central process from the first-order neurons in all three cranial nerves
terminates in the ipsilateral nucleus solitarius of the medulla. The cell body of
second-order neurons comprises the gustatory nucleus located in the rostrolateral
portion of the solitary nuclear complex. Second-order neurons from the gustatory
nucleus project to the ipsilateral thalamus and terminate in the ventral posteromedial
nucleus. In the thalamus, cells serving taste are grouped separately from those
related to other sensory modalities of the tongue. Third-order neurons in the
gustatory system project from the parvicellular region of the ventral posteromedial
nucleus to two regions in the cerebral cortex: the gustatory region in the postcentral
gyrus (area 3b of Brodmann) and the face region of the frontral operculum and
insula.
Unlike most other sensory systems, the central pathway for gustatory
information is not crossed. The somatic sensory information from the tongue projects
to the contralateral sensory cortex but gustatory information remains uncrossed.
Clinical Aspects. Loss of taste is called ageusia. Disruption of taste is usually
associated with a disorder of one of the cranial nerves that subserves this sense.
Because the three nerves serve different regions of the tongue and each region
selectively senses different stimuli, individual cranial nerve involvement can be
determined by the missing taste category. Since the chorda tympani branch of the
facial nerve passes through the middle ear on its way to innervate the anterior two
thirds of the tongue, partial ageusia is one possible complication of middle ear
disease or surgery. A decrease in the sensitivity of taste often occurs after the age of 40.
From birth on, the number of taste buds decreases constantly, but after 40 the drop in
taste bud reproduction becomes much steeper. The large number of taste buds present
at birth helps account for the greater taste acuity in babies (baby food is only bland
to those with fewer buds to taste it). Further, taste buds are not distributed evenly
across the tongue. The center of the tongue, with fewer taste buds, is relatively tasteblind. Taste perception contains a heredity factor, so that some individuals are unable
to taste certain chemicals, probably due to the lack of specific receptor cells.
Preferences and cravings for certain foods change with metabolic conditions, as seen
in some pregnant women.
Clinical testing of Vagus nerve is difficult in spite of the great size and many
functions of nerve. Unilateral paralysis of this motor portion of the vagus produces
ipsilateral paralyses of the palatal, pharyngeal muscles. The voice is hoarse or brassy as
a result of weakness of the vocal cord, and speech has a nasal twang in lesion
producing weakness of the soft palate, particularly if bilateral. Lesion of the recurrent
laryngeal branch of the vagus nerve produce weakness or paralysis of the ipsilateral
vocal cord and the voice is coarse and husky. The soft palate is observed as the patient
says “ah”. Normally the median raphe rises in the midline. However if one side is
weak, there will be deviation to the intact side. In unilateral involvement of the vagus,
swallowing is ordinarily not impaired, but in bilateral lesions there will be dysphagia
and regurgitation of the fluids through the nose. The sensory finding associated with
vagus nerve lesion are difficult to test clinically.
Bulbar syndrome
Gag reflex is absent or decreased
The tongue is atrophic
The pathologic oral reflexes is absent
Pseudobulbar syndrome
Gag reflex is present
The tongue is not atrophic
The pathologic oral reflexes are present
Paralysis is unilateral or bilateral
Paralysis is only bilateral
May be (dyspnea, apnea, periodic
respiration – Cheyne-Stokes breathing)
Self assessment:
Tests for self-assessment:
1. Name the symptoms of XI nerves lesion.
2. Name the symptoms of XII nerves lesion.
3. Name the symptoms of bulbar syndrome.
4. Name the symptoms of pseudobulbar syndrome.
5. Describe the symptoms of IX nerves lesion.
6. Describe the symptoms of X nerves lesion.
7. Describe the Jackson’s syndrome.
8. Name the pathologic oral reflexes.
9. Describe the Awelis’ syndrome.
10.Describe the Schmidt’s syndrome.
11.Describe the Valenberg-Zakcharchenko’ syndrome.
Tests
1.
a)
b)
c)
d)
e)
2.
a)
b)
c)
d)
e)
What is the motor nucleus of the Vagal nerve:
Nucl. dorsalis;
Nucl. ambiguus;
Nucl. Alae cinereae;
Nucl. Tractus spinalis;
Nucl. Salivatirius superior.
Lesion of what nerve occurs if the damage is situated in the jugular foramen:
Glossopharyngeal nerve;
Trochlear nerve;
Abducens;
Hypoglossal nerve;
Facial.
3. Nuclear lesion of Hypoglossal nerve differentiates from the supranuclear
lesion by the following symptom:
a)
b)
c)
d)
e)
tongue deviation;
the lack of tongue movements;
fibrillation;
combined lesion of the Vagus;
all of that
Real-life situations:
1.
Name the symptoms of bulbar paralysis.
2.
In patient with cranial basis rupture dysphagia and dysphonia symptoms
appeared incisively. Objective: immovable left part of palate, there is no reflex from
palate and left part of posterior gullet wall. The patient can’t raise his left hand
upper then horizontal level and turn his head to the right side. What is damaged?
Localize process.
3.
In patient without dysfunction of swallowing. Voice and language,
reflexes of oral automatism were found. What is damaged?
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.