Cranial Nerve I Olfactory Nerve ƒ Nerve fiber modality: Special sensory afferent Cranial Nerves 1, 5, 7-12 ƒ Function: Olfaction ƒ Remarkable features: – Peripheral processes act as sensory receptors (the other special sensory nerves have separate Warren L Felton III, MD receptors) Professor and Associate Chair of Clinical – Primary afferent neurons undergo continuous Activities, Department of Neurology replacement throughout life Associate Professor of Ophthalmology – Primary afferent neurons synapse with secondary neurons in the olfactory bulb without synapsing Chair, Division of Neuro-Ophthalmology first in the thalamus (as do all other sensory VCU School of Medicine neurons) – Pathways to cortical areas are entirely ipsilateral

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Crania Nerve I Cranial Nerve I Clinical Testing Pathology ƒ Anosmia, hyposmia: loss of or impaired ƒ Frequently overlooked in neurologic olfaction examination – 1% of population, 50% of population >60 years ƒ Aromatic stimulus placed under each – Note: patients with bilateral anosmia often report nostril with the other nostril occluded, eg impaired taste (ageusia, hypogeusia), though coffee, cloves, or soap taste is normal when tested ƒ Note that noxious stimuli such as ƒ Dysosmia: disordered olfaction ammonia are not used due to concomitant – Parosmia: distorted olfaction stimulation of CN V – Olfactory hallucination: presence of perceived odor in the absence of odor ƒ Quantitative clinical tests are available: • Aura preceding complex partial seizures of eg, University of Pennsylvania Smell temporal lobe origin Identification Test (UPSIT) • Schizophrenia

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Cranial Nerve I Cranial Nerve I Pathology Pathology ƒ Nasal passages, Olfactory epithelium, Central Pathways – Nasal: stimuli do not reach olfactory receptors ƒ Central pathways: olfactory bulb, •Smoking olfactory tract, central projections • Nasal and paranasal sinus disease: infection (influenza, herpes simplex, hepatitis), allergy, antihistamine – Intracranial tumor: olfactory groove overuse, cocaine – Olfactory epithelium: impairment of receptors or axons meningioma, frontal lobe glioma • Trauma: tearing of epithelium at cribiform plate – 5-10% of head trauma patients have impaired – Aneurysm: anterior cerebral artery olfaction – Degenerative disease: Alzheimer’s, – Note: head trauma causing dural tear may result in CSF rhinorrhea Parkinson’s, Huntington’s • Intranasal tumor: papilloma • Toxic: certain antibiotics (aminoglycosides, tetracycline), • Note: olfaction diminishes with age corticosteroids, opiates, organic solvents

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1 Cranial Nerve V Cranial Nerve V Trigeminal Nerve Three Divisions Nerve Fiber Modalities ƒ Ophthalmic branch (V1): superior orbital foramen – Forehead, nose, and anterior scalp to the lateral epicanthus of the eye – Cornea, eye, orbit ƒ General sensory afferent – Nasal and frontal sinus mucosa – Function: All general sensory modalities from the: – Dura mater of the falx ƒ Maxillary branch (V2): foramen rotundum • Face and anterior scalp – Cheek to the corner of the mouth, sparing the angle of the jaw • Conjunctiva and eye – Upper lip, teeth and gums, and palate – Floor of middle cranial fossa • Paranasal sinuses and nasal cavities ƒ Mandibular branch (V3): foramen ovale • Oral cavities, anterior 2/3 of the tongue, and teeth – Sensory •Chin • Part of the external tympanic membrane • Lower lip, teeth, and gums • Meninges of the anterior and middle crania fossae • Anterior 2/3 of tongue • Dura mater above the tentorium ƒ Branchial motor efferent –Motor – Function: Innervation of the muscles of mastication ƒ Note: brainstem lesions may produce an ‘onion skin’ pattern if sensory loss centering on the nose and lips

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Cranial Nerve V Cranial Nerve V Sensory Clinical Testing Motor Clinical Testing ƒ Palpatation of masseter and temporalis ƒ Pain (pinprick), touch (cotton swab, light muscles as the patient clenches the teeth finger touch), and temperature (cool tuning ƒ Forced jaw opening, closure, and lateral fork) are tested in each of the three divisions movement ƒ Note that vibration (tuning fork) is – Note: unilateral CN V motor weakness results in jaw transmitted through the skull and is normally deviation to the ipsilateral side with mouth open appreciated approximately equally on each ƒ Jaw (mandibular) jerk: tapping the side of the forehead when unilaterally examiner’s finger placed on the patient’s stimulated chin normally elicits a brisk but slight contraction – Significant asymmetry of vibration is usually – An exaggerated response is a sign of upper motor interpreted as a nonphysiologic response, so called neuron pathology above the foramen magnum ‘splitting’ of vibratory sensation at the forehead – An unelicitable response has little clinical significance

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Cranial Nerve V (and VII) Cranial Nerve V Clinical Testing Pathology ƒ Corneal Reflex ƒ Supranuclear, Brainstem, – CN V (V1): afferent Preganglionic/Ganglion, Peripheral branches – CN VII: efferent – Supranuclear: ischemia, hemorrhage, neoplasia, – Cotton wisp touched to the cornea unilaterally demyelinating disease, trauma produces a bilateral blink response • Contralateral facial and body sensory loss • A unilateral CN V lesion results in absent – Brainstem: as above, synrinx blink bilaterally with stimulation ipsilateral to • Ipsilateral facial sensory loss the lesion – Preganglionic and gasserion ganglion: • A unilateral CN VII lesion results in absent • tumor (meningioma, schwannoma) blink ipsilateral to the lesion with stimulation • inflammation (sarcoid) of either cornea • infection (bacterial, fungal, mycobacterial) 11 12

2 Cranial Nerve V Cranial Nerve V Pathology Pathology ƒ Peripheral branches ƒ Trigeminal Neuralgia (Tic deloureux) – Infection: – The most common neuralgia • Herpes zoster • Approximately 4 per 100,000; women to men 3:2 – Symptoms: – Usually V1: acute herpetic eruption and pain • Paroxysms of extremely severe pain in one or more of the divisions of the trigeminal nerve, usually V2 or V3 – May result in post-herpetic neuralgia: burning, • Pain is typically lancinating, lasting a few seconds aching, or lancinating; mild sensory loss; • Pain may occur spontaneously or be triggered by touch, eating, aggravated by touch or talking • Sensory testing of CN V is usually normal – May result in corneal damage and visual loss –Pathology • Other: bacterial, fungal • Usually of unknown etiology • May be due to compression by a tortuous blood vessel – Inflammation: sarcoid, Sjogren’s syndrome, SLE • May be a symptom of multiple sclerosis – Tumor: sinus tumor, lymphoma, skin cancer, metastasis – Treatment • Medication: anticonvulsants (eg carbamazepine, gabapentin) –Trauma • Less commonly, surgery

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Cranial Nerve VII Cranial Nerve VII Facial Nerve Clinical Testing Nerve Fiber Modalities Muscles of Facial Expression ƒ Branchial motor efferent ƒ Observation of the patient’s facial expression – Function: Innervate the muscles of facial expression, plus when relaxed and when speaking stapedius, stylohyoid, and posterior belly of digastric ƒ Observation when the patient is asked to ƒ Visceral motor (parasympathetic) efferents wrinkle the forehead, smile, forcibly close the – Function: Stimulation of the lacrimal, submandibular, and eyes, puff the cheeks, and contract the sublingual glands, and mucous membranes of the nose and hard and soft palates platysma ƒ General sensory afferent ƒ Weakness is demonstrated by facial – Function: General sensation from the concha of the auricle, asymmetry, diminished nasolabial fold, possibly the external auditory meatus, and part of the external widened palpebral fissure, reduced forehead tympanic membrane wrinkling, impaired smile, and inability to ƒ Special sensory afferent puff out the cheeks – Function: Taste sensation from the anterior 2/3 of the tongue ƒ Corneal reflex (see CN V) 15 16

Cranial Nerve VII Cranial Nerve VII Upper and Lower Motor Neuron Clinical Testing Lesions Taste ƒ Upper motor neuron lesions: contralateral deficit – Frontalis and obicularis oculi muscles are spared due to bilateral motor cortex input to the part of the facial nucleus supplying ƒ Tested using a moist cotton swab these muscles dipped into sweet, sour, or salty – Loss of lower facial motor voluntary expression contralateral to the CNS lesion due to unilateral input to the part of the facial preparations nucleus supplying these muscles – Note: Facial motor emotional expression is sometimes ƒ The patient protrudes the tongue, the preserved as the corresponding neuronal input follows a different pathway cotton swab is applied unilaterally, and ƒ Lower motor neuron lesions: ipsilateral deficit the patient is asked to identify the taste – Both upper and lower muscles of facial expression are affected ipsilateral to the lesion without retracting the tongue – Note: Taste is affected if the lesion is proximal to the chorda tympani and spared if the lesion is distal to this nerve 17 18

3 Cranial Nerve VII Cranial Nerve VII Pathology Pathology – Peripheral Nerve ƒ Upper Motor Neuron, Brainstem, • Facial canal: facial weakness, loss of taste (if lesion proximal to chorda tympani), variably hyperacusis (if Peripheral Nerve lesion proximal to nerve to stapedius), and decreased – Upper motor neuron/central facial palsy: lacrimation and salivation (if lesion proximal to greater superficial petrosal nerve) ischemia, hemorrhage, tumor, trauma, – Bell’s palsy infection, demyelination – Tumor: cholesteatoma, hemangioma • Contralateral lower facial and extremity –Trauma weakness • Stylomastoid foramen: facial weakness in isolation –Trauma – Brainstem: ischemia, hemorrhage, tumor, – Tumor: parotid gland tumor trauma, infection, demyelination – Note: paradoxically tearing may increase ipsilaterally due to tears spilling over a weakened lower lid and to increased • CN VI often involved stimulation by corneal exposure

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Cranial Nerve VII Cranial Nerve VII Pathology Pathology ƒ Bell’s Palsy – Facial palsy of historically idiopathic etiology ƒ Hemifacial spasm • Herpes simplex infection now most commonly accepted – Unilateral involuntary variable clonic contraction of facial etiology muscles, painless – The most common CN VII disorder – Etiology • Incidence: 23 per 100,000 • Idiopathic –Symptoms • Compression of CN VII by branch of basilar artery • Acute unilateral facial paralysis over hours to days • May develop following Bell’s palsy – Often a viral prodrome – Treatment • Variable loss of taste, lacrimation, and salivation, and hyperacusis • Medication: baclofen, gabapentin, carbamazepine • Numbness or pain of the ear, face, and tongue • Botulinum toxin – Treatment • Surgical decompression • Antviral: acyclovir, famcyclovir ƒ Anomalous regeneration following CN VII lesion • Corticosteroid: prednisone – Marcus-Gunn ‘jaw wink’ phenomenon: jaw movement • Management of ocular complications, eg corneal exposure causes ipsilateral partial ptosis – Prognosis – Crocodile tears: uninlateral tearing with salivation • Majority recover fully over several weeks to months 21 22

Cranial Nerve VIII Cranial Nerve VIII Vestibulocochlear Nerve Clinical Testing Nerve Fiber Modality Cochlear Nerve ƒ Gently rub fingers near the patient’s ear and ask the patient to identify the sound and symmetry between the two ears ƒ Special sensory afferent ƒ Rinne test: 256 Hz tuning fork held to the mastoid and then near the patient’s ear for comparison – Function – Normal response: the patient hears the vibrating sound better with air conduction than with bone conduction • Vestibular nerve: Balance – Abnormal response: bone conduction is greater than air conduction, ie there is defect of the conduction of sound in the external auditory canal or • Cochlear nerve: Hearing middle ear oscicles, conductive hearing loss ƒ Weber test: 256 Hz tuning fork held to the middle of the forehead – Normal response: perception of the vibrating sound in the midline – Abnormal response: sound lateralizes to one ear • Abnormal response indicating a conduction defect: the sound lateralizes to the affected side • Abnormal response indicating a sensorineural hearing defect: the sound lateralizes to the opposite ear

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4 Cranial Nerve VIII Cranial Nerve VIII Clinical Testing Clinical Testing Vestibular Nerve Vestibular Nerve ƒ Observation of nystagmus ƒ Nystagmus of peripheral vestibular disorders is best ƒ Dix-Hallpike positional test: patient observed with reduced ocular fixation – Examination in dim illumination positioned rapidly from a seated to supine – Observation of nystagmus on optic funduscopic exam with the position, the head hanging centrally, then to opposite eye fixating and then covered (impairing fixation) ƒ Nystagmus of peripheral and central origins the right, then to the left – Nystagmus of peripheral origin is: – Nystagmus of peripheral vestibular origin: latency of • Suppressed by fixation 2-5 seconds, mixed horizontal-rotary, fast component • Of mixed character, with both horizontal and rotary features beating away from the diseased side, lasting 5-60 • Unidirectional, with the fast component beating away from the affected side, regardless of the direction of gaze seconds, fatigues with repetition – Nystagmus of central origin is: – Nystagmus of central origin: no latency, horizontal, • Not suppressed by fixation vertical, rotary, or mixed, often multidirectional, often • May be purely horizontal, vertical, or rotary, or of mixed type • Multidirectional, the fast component changing with the direction lasting >60 seconds, does not fatigue of gaze 25 26

Cranial Nerve VIII CN VIII Pathology Primarily Affecting Hearing Pathology Primarily Affecting ƒ Conductive hearing loss Vestibular Function – Sound is not transmitted to the inner ear – Causes: excess cerumen or foreign body in external canal, ƒ Benign paroxysmal positional vertigo (BPPV) otosclerosis, external or middle ear infections, allergy with serous – Most common; 50% of peripheral vertigo otitis, tympanic membrane perforation – Symptom: vertigo precipitated by movement or change in ƒ Sensorineural hearing loss position of head or body, eg getting out of bed or turning – Most common type; 23% population >60 years over in bed – Disorder of CN VIII or cochlea – Etiology: dislodged otoconia in the semicircular canals due – Causes: older age (sometimes called presbycusis), Meniere’s to trauma, infection, or degeneration disease, toxins (eg high dose aspirin), noise – Treatment: ƒ Central hearing loss • Medication – Vestibular suppressants: meclizine, dimenhydrinate –Rare (Dramamine), lorazepam, diazepam, scopolamine – Causes: pure word deafness (disturbed auditory comprehension with intact visual comprehension), auditory agnosia (inability to – Antiemetics: meclizine, metoclopropamide, recognize nonverbal sounds, eg ringing telephone, with otherwise promethazine, prochlorperazine intact hearing) • Vestibular excercises

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CN VIII CN VIII Pathology Primarily Affecting Vestibular Pathology Cerebellopontine Angle Function ƒ Vestibular neuritis (vestibular neuronitis) ƒ Clinical syndrome – Symptoms: acute vertigo, nausea, and ataxia, with intact hearing, – Progressive loss of hearing and vertigo usually monophasic, lasting 2-3 days to 1-2 weeks – Sometimes associated with symptoms of involvement by CN • When hearing affected termed labyrinthitis VII (most common), V, VI, IX, X – Etiology: viral infection of vestibular ganglion ƒ Etiology – Treatment: – Acoustic/vestibular neuroma (schwannoma): derived from • Vestibular suppressants and antiemetics and vestibular excercises Schwann cells of the vestibular portion of CN VIII similar to BPPV • Corticosteroids and antiviral agents – Meningioma ƒ Meniere’s disease (endolymphatic hydrops) ƒ Diagnosis – Symptoms: episodic recurrent vertigo, fluctuating hearing, monaural – Neuroimaging: MRI, CT fullness, and tinnitus – Brainstem auditory evoked potentials – Etiology: dilation and rupture of endolymphatic compartment of inner ear due to trauma, autoimmune process, or genetic predisposition ƒ Treatment – Treatment – Surgery • Medications similar to BPPV – Radiotherapy • Reduction of dietary salt plus salt-wasting diuretic

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5 Cranial Nerve IX Cranial Nerve IX Glossophayngeal Nerve Glossopharyngeal Nerve Nerve Fiber Modalities Nerve Fiber Modalities ƒ General sensory afferent – Function: General sensation to: • Posterior 1/3 of tongue, tonsils, and pharynx ƒ Branchial motor efferent • External ear – Function: innervates stylopharyngeus • Internal surface of tympanic membrane ƒ Visceral sensory afferent ƒ Visceral motor (parasympathetic) – Function: • Carotid body chemoreceptors efferent • Carotid body baroreceptors – Function ƒ Special sensory afferent – Function: Taste from the posterior 1/3 of the tongue • Parotid gland Note: CN IX provides both general sensation and taste • Carotid body to the posterior 1/3 of the tongue

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Cranial Nerve IX (and X) Cranial Nerve IX Clinical Testing Pathology

ƒ Gag Reflex – CN IX: afferent (some contribution by CN X) – CN X: efferent ƒ Supranuclear lesions – Procedure: cotton swab or tongue blade gently touched to each side of the soft palate or posterior pharynx – Normal response: Bilateral palatal elevation and gag – Pseudobulbar palsy: see CN X – Abnormal response • Unilateral CN IX lesion: no response of the palate bilaterally when ƒ Brainstem stimulating the side ipsilateral to the lesion; bilateral palatal elevation when stimulating the side contralateral to the lesion and to command to say ‘aah’ – Often associated with CN X • Bilateral CN IX lesion: no response of the palate bilaterally when stimulating either side; palatal elevation remains intact to command to – Etiologies: ischemia, hemorrhage, say ‘aah’ • Unilateral CN X lesion: no response of the palate ipsilateral to the infection, demyelination, trauma lesion with stimulation of either side; contralateral palateral elevation causes deviation of the palate and uvula away from the side of the lesion • Bilateral CN X lesion: no response of the palate when stimulating either side and no response of the palate to command to say ‘aah’

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Cranial Nerve IX Cranial Nerve IX Pathology Pathology ƒ Glossopharyngeal Neuralgia – Rare: 0.7 per 100,000 – Severe, sharp, lancinating pain in the region of the tonsil, ƒ Cerebellopontine angle (see CN VIII) radiating to the ear • Similar to trigeminal neuralgia in timing and nature of pain ƒ Jugular foramen • May occur spontaneously or be triggered by swallowing, chewing, or speaking – CN IX and X, sometimes associated with • May be associated with syncope CN XI and XII – Pathology • Usually of unknown etiology – Etiology • Occasionally due to compression of CN IX by carotid aneurysm, peritonsillar infection, or tumors of the oropharynx • Neoplasm or skull base • Infection – Treatment • Medication: anticonvulsants (eg, gabapentin, • Trauma carbamazepine) • Surgery 35 36

6 Cranial Nerve X Cranial Nerve X Vagus Nerve Vagus Nerve Nerve Fiber Modalities Nerve Fiber Modalities

ƒ General sensory afferent ƒ Branchial motor efferent – Function: General sensation from: – Function: Innervates muscles of the oropharynx • Posterior meninges • Superior, middle, and inferior constrictors • Concha, posterior ear, and external acoustic meatus • Levator palati, salpingopharyngeus, palatopharyngeus, • Part of the external tympanic membrane palatoglossus • Pharynx and larynx •Cricothyroid ƒ Visceral sensory efferent • Intrinsic muscles of the larynx – Function: ƒ Visceral motor (parasympathetic) efferent • Larynx, trachea, esophagus, and thoracic and abdominal – Function viscera • Smooth muscle and glands of the pharynx, larynx • Aortic arch stretch receptors • Thoracic and abdominal viscera • Aortic body chemoreceptors • Cardiac muscle

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Cranial Nerve X Cranial Nerve X Clinical Testing Pathology

ƒ Observation of the palate on phonation, ƒ Supranuclear lesions the patient instructed to say ‘aah’ – Pseudobulbar palsy: disruption of corticobulbar tracts supplying CN motor nuclei from the precentral motor – A lesion affecting the palate may produce cortex produces a disturbance of speech, swallowing, nasal speech and chewing, often associated with emotional lability and dementia ƒ Gag reflex (see Cranial Nerve IX) • Unilateral lesion may produce no symptom or mild ƒ Vocal cord paralysis symptoms • Note: not solely a supranuclear disorder of CN X – May produce hoarse speech – Etiologies: ischemia, hemorrhage, infection, – Note: speech may be normal due to demyelination, trauma, degenerative compensation by the intact contralateral vocal ƒ Brainstem cord – Usually associated with CN IX

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Cranial Nerve X Cranial Nerve X Pathology Pathology

ƒ Cerebellopontine angle (see CN VIII) ƒ Glomus Jugulare Tumor ƒ Jugular foramen (see CN IX) – Pathology: Vascular tumor arising from the glomus bodies ƒ Recurrent laryngeal nerve (paraganglia chemoreceptor cells) of the jugular bulb • Erodes the jugular foramen – Clinical presentation: ipsilateral vocal cord paralysis • Causes compression of CN IX, X, and XI (sometimes and hoarseness extending to involve CN VIII and XII) – Left recurrent laryngeal nerve has longer course, with – Peak incidence middle adult life looped recurrence in the chest around the aorta; the – Symptoms and signs: ipsilateral pulsatile tinnitus and right is located in the neck occasional bruit, impaired gag reflex, hoarse voice, –Etiologies: dysphagia, ipsilateral sternocleidomastoid weakness (CN • Left recurrent laryngeal nerve: aortic arch XI), and occasionally ipsilateral hearing loss and vertigo (CN aneurysm, pulmonary neoplasm, mediastinal VIII), tongue paralysis (CN XII), and Horner’s syndrome adenopathy – Diagnosis: neuroimaging (MRI preferred) • Right or left recurrent laryngeal nerve: neck – Treatment: mastoidectomy, resection, radiation

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7 Cranial Nerve XI Cranial Nerve XI Spinal Accessory Nerve Clinical Testing Nerve Fiber Modality ƒ Sternocleidomastoid muscle – Tilts the head up and towards the opposite side – Assess muscle bulk with the face turned to the opposite side ƒ Branchial motor efferent – Patient tilts the head against resistance ƒ Trapezius muscle – Function: innervates – Retracts the head and elevates, retracts, and rotates the • Sternocleidomastoid (sternomastoid) scapula; enables abduction of the shoulder beyond 90 degrees – Assess muscle bulk with the shoulder and upper back fully muscle exposed – Impaired trapezius motor function causes downward and lateral • Trapezius muscle rotation of the scapula (winged scapula) and downward displacement of the shoulder – Test shoulder shrug against resistance ƒ A unilateral CN XI lesion causes: – Ipsilateral shoulder shrug weakness and winged scapula – Impaired head turn to the contralateral side

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Cranial Nerve XI Cranial Nerve XI Pathology Pathology ƒ Supranuclear lesion – Effect is incompletely understood ƒ Distal peripheral CN XI lesions ƒ Brainstem lesion – Axons to the trapezius muscle are potentially more vulnerable in the posterior triangle of the neck – Usually associated with CN XII than are those to the sternocleidomastoid – Etiologies: ischemia, hemorrhage, infection, –Etiologies demyelination, syrinx, trauma • Compression by carrying heavy loads on the ƒ Region of foramen magnum shoulder – Usually associated with CN XII, also CN IX and X • Excessive shoulder rotation or compression – Etiologies: platybasia, Paget’s disease, tumors during surgery (meningioma, metastasis) • Neck bites ƒ Jugular foramen (see CN IX) • Attempted suicide by hanging

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Cranial Nerve XII Cranial Nerve XII Hypoglossal Nerve Clinical Testing Nerve Fiber Modality

ƒ Somatic motor efferent ƒ Examination of the tongue at rest for – Function: Innervates position, bulk, atrophy, and fasciculations • 3 of the 4 extrinsic muscles of the tongue ƒ The patient protrudes the tongue, –Genioglossus, styloglossus, and moves it side to side, and resistance hypoglossus against the cheek is assessed »(Palatoglossus supplied by CN X) • All intrinsic muscles of the tongue

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8 Cranial Nerve XII Cranial Nerve XII Pathology Pathology

ƒ Upper motor neuron lesion – Unilateral lesion results in paralysis of the contralateral genioglossus ƒ Supranuclear lesions muscle (supplied only by contralateral CNS, unlike the other tongue muscles which are bilaterally innervated by the CNS), causing the – Etiologies: ischemia, hemorrhage, tumor, trauma tongue to deviate away from the side of the CNS lesion – Bilateral upper motor lesions cause a decrease in rapidity of tongue ƒ Brainstem lesions movements – Often associated with CN XI ƒ Lower motor neuron lesion – Unilateral lesion results in ipsilateral paralysis of the tongue, causing – Etiologies: ischemia, hemorrhage, demyelination, the tongue to deviate to the side ipsilateral to the lesion syrinx, tumor, trauma – Bilateral lower motor lesions result in bilateral tongue paralysis, impaired tongue protrusion, and poor lingual sounds (‘la, la, la’) ƒ Region of foramen magnum (see CN XI) ƒ Note: With a unilateral lesion the tongue deviates to the side of its weak muscle or muscles, whether the lesion is upper ƒ Jugular foramen (see CN IX) motor or lower motor neuron in origin

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Cranial Nerve XII Pathology

ƒ Carotid Artery Dissection – Pathology: Dissection of the intima of the carotid artery, allowing blood to enter the arterial wall, forming an intramural hematoma, and causing carotid artery stenosis, aneurysm, and/or mass effect • Usually due to trauma: direct blow, lifting weights • May occur spontaneously – Symptoms and signs • Pain involving the anterior neck, frontotemporal area, face, or eye • Horner’s syndrome • Cerebral or retinal stroke or TIA • CN IX, X, XI, XII palsy due to compression – Diagnosis: neuroimaging • MRA, CTA, cerebral angiogram – Treatment • Anticoagulation • Surgical or neuororadiologic intervention

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