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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.