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1Presentation for 5th year students by Professor of clinical neurology Cranial nerves disorderPresentation for 5th year students byHayder k. Hassoun MDProfessor of clinical neurologyKufa medical college
2vision (Contain 38% of all the axons connecting to the brain.) NervesTypeFunctionI Olfactorysensoryolfaction (smell)II Opticvision (Contain 38% of all the axons connecting to the brain.)III Oculomotormotor*Eyelid and eyeball musclesIV Trochleareyeball musclesV TrigeminalmixedSensory: facial and mouth sensation Motor: chewingVI Abducenseyeball movementVII FacialSensory: taste Motor: facial muscles and salivary glandsVIII Auditoryhearing and balanceIX GlossopharyngealSensory: taste Motor: swallowingX Vagusmain nerve of the parasympathetic nervous system (PNS)XI AccessoryMotor*Swallowing; moving head and shoulderXII Hypoglossaltongue muscles
4CN Disorder CN disorder can be confined to single nerve such as : olfactory in cases of closed trauma or Meningiomatrigeminal N as in neuralgiafacial N in bell’s palsy and hypoglossal in cases of carotid dissectionor to multiple nerves as in cavernous sinus disease affecting 3,4 and 6 or inflammatory process affecting base of skull ,or infiltrative disorders which can affect ,7,8,9,10, 7 ,6 ,3,4, ----in different pattern
5Olfactory nerve disease ------loss or distortion of smell (paraosomia or dysosmia) Anatomy: it starts with upper part of nasal mucosa as filaments a-----cribriform plate then olfactory bulb---tract ---to the rhino cortex.It is important to know the abnormality result from damage to this nerve unilateral or bilateral, is it loss of smell or distortion? BothCauses Loss of smell causes:Nasal obstruction –flue or allergyFrontal lobe disease or anterior cranial fossa ex: Meningioma and F.L tumor which may presented with affection of olfaction as 1st S.Trauma.Congenital ex : Kallmann syndromeDistortion of smell seen in psychiatric disease and epilepsy.
6Retina and optic nerveAnatomy: the retina is a neural tissue of the eye contains 10 layers with 9 distinct cells ,the function is to detect visible light ---transduce photic energy of light in to neural signals and perform an initial analysis of visual information before sending it to the brain via optic nerve (nasal and temporal fibers) which is the axons of inner most cell of retina : ganglionic cell that turn 90 degree changing the orientation from horizontal along inner retinal surface to vertical through the retina .The g. cell receive input from bipolar cells. The gathering axons of G. cells at the scleral canal form optic nerve disk of the fundus and called optic nerve head.There is fibers carry the visual information from fovea centralis of retina forming thick central layer of optic nerve which enter in temporal quadrant of disk = papillomacular which is the target of many disease causing temporal pallor as in MS which result in central scotoma.
101-OPTIC NERVE AND RETINA Optic N. Begins at optic disk as intraocular portion ends at the point where it leaves the scleral (lamina cribrosa) to be orbital portion (NF become myelinatd) which is affected my MS, there fore we think that optic nerve is misnomer it is not peripheral N. but a central white matter of brain and also it is pathed in CSF and invested with meninges which fused with the orbital connective tissue forming optic nerve sheath.Intracranial portion ;1st part runs in through bony optic canal then pass below the frontal lobe------optic chiasm (site of crossing of temporal fibers of both optic nerves) above pituitary gland -----optic tracts------optic radiation-----occipital lobes.Disorders: depending on site of involvement1-OPTIC NERVE AND RETINAOptic disk and anterior optic N optic neuritis, AION, papilloedema, glaucoma,Posterior optic N.: like post. ION, optic neuritis, compressive, toxic, genetic, and metabolic cause.
11Optic neuritis ** It is common presenting feature in MS **c/f: brief prodrome of peri ocular pain, over days worsened with eye movement.Visual loss often sudden ? and rapid severs with worsening over days but degree of visual loss varies.**Examination: central V. loss in affected eye which is usually unilateral.Pupillary defect.**Fundoscopic exam. Shows in acute stage Swelling of disc, some times associated with small hemorrhages, but if the posterior portion is affected the disc is normal. Venous pulsation is present.In chronic stage -----optic disk pallor or and optic atrophy (white disk=chalky disk)Recovery of vision to near normal occurs over 2-3 months.**Treatment: methylpredinsolone (1g daily for 3 days followed by oral prednisolone) to hasten the recovery and provide some protection against new MS event
12Other causes of optic disk swelling -Papilloedema***-Obstruction of ocular venous drainage (central retinal vein occlusion, cavernous s. thrombosis)-Systemic disorder affecting R. blood vessels (HT, vasculitis, hypercapnia)-Optic nerve damage (optic neuritis, Leber’s OA, ischemia, toxins like methanol, infiltrative lesions, Glioma, and lymphomas)***Papilloedema =swelling of optic disk due to increase ICP in which the patient have feature of increased ICP as headache visual blurring aggravated with change in posture especially standing & associated with vomiting .On examination ,there is normal vision in early stages apart of enlarged blind spot (Small area in central field seen in every person due absence of cone and rod cell in center of disk), Pupillary reflexes also normal .Fundoscopic exam revealed initially absence of venous pulsation then swelling of disc , some times there is area of hemorrhage.In late stage there will damage to ON fibers result in optic atrophy (secondary OA).***Causes:-Cerebral mass (tumor or abscess), hydrocephalus, hematoma, idiopathic
13Optic atrophy It can be: primary due to causes affecting the optic nerve fibers primarily(The O. disk appears pale initially then became whitish)secondary due to affection of optic nerve fibers as result of PD.CAUSESSame causes of optic nerve damage which starts initially as ON swelling(ON &PD)---then OAOthers areIschemia as in DM and giant cell arteritis.metabolic (B12 deficiency)inherited as in friedreich’s ataxia.Toxins(methanol ) and drugs
142-OPTIC CHIASM is resulting in none or visual blurring 2-OPTIC CHIASM is resulting in none or visual blurring .clinical exam will show bitemporal hemianopia? It is associated with pituitary abnormality .common causes are pituitary tumor, craniopharengioma and sarcoidosis.3-OPTIC TRACT; it results in disturbed vision in one side of midline .examination showed contralateral homonymous hemianopia.common causes tumor & inflammatory disease.4-OPTIC RADIATION at temporal lobe or parietal lobe, common causes are tumor, stroke and inflammatory disease leading to disturbed vision in one side of midline.--Temporal lobe results in upper quadrant HH associated with language or memory disturbance.--Parietal lobe results in lower quadrant HH associated with sensory symptoms and signs.5-OCCIPITAL LOBE: results in disturbed vision in one side of midline associated with difficulty in reading and damage to other Str. Supplied by PCA, common causes are tumor, stroke and inflammatory disease
16EYE MOVEMENT DISORDER (3rd, 4th, and 6th cranial nerves) Under normal circumstances the eyes move conjugately through vertical and horizontal allows fusion of objects at different distance. the control of eye movement begins in frontal eye fields, and pathways descends with input from visual cortex, superior colliculus and cerebellum controlling vertical gaze center at the midbrain and horizontal gaze center at the pons(may be part of 6th n. nucleus).Then these centers sends their impulses to cranial nerves nuclei 3,4(in midbrain) &6(in pons) which are connected to each others by medial longitudinal fasciculus MLF which is important in horizontal movement of tow eyes.The 3rd nerve supplying all EOM except SO (by 4th) and LR (BY 6th nerve).3rd gives also branches to levator palpebrea superioris muscle and parasympathetic twigs to ciliary body for accommodation and pupil constriction (via cholinergic effect)ANATOMY: these CN originated from nuclei in midbrain (3rd & 4th) and pons (6th).they passes together intrameningeal course at the base of skull then in to cavernous sinus with 1st division of trigeminal nerve, then they passes in superior orbital fissure, then to the orbit (supplying the eye)
17Cerebral level-frontal eye field control all below Brainstem level –gaze centerVertical gaze at mid brain and horizontal at ponsNuclear level 3.4 and 6 nucleus -----
18Clinical features3rd nerve palsy ; complete palsy results in ptosis , dilated pupil and eye tends to rest in a down and lateral position due to unopposed action of SO&LR.The pupil is often spared in cases of ischemic lesions (diabetes) =medical 3rd while in compressive lesion (surgical 3rd) the pupil often is involved as in case of aneurysm of P communicating A. or compressive lesions.Trochlear N.: vertical diplopia specially on going downstairs so the patient tilts his head opposite to side of lesion.Abducent N.: horizontal diplopia (double vision) on looking to side of lesion horizontally.Approach to diplopia: determine the site at which the separation of 2 object is maximum, then determine the outset image (faint less clear) which the false image by cover –uncover test, the outer image is belonging to abnormal eye (paretic one).Common causes of 3rd, 4th and 6th cranial nerves palsy in isolation or group according to site.
19Infarction, hemorrhage Demyelinating, tumor 3rd in mid brain Site causes nerve (s) involvedBrain stemInfarction, hemorrhageDemyelinating, tumor3rd in mid brain6th in ponsIntra-menig.Raised ICPMeningitisAneurysmc-p angletrauma-6 while 3 in uncal H.3,4,63 or 6-6-3 ,4 and /or 6Cavernous S.Infection/thrombosisCarotid aneurysmCartico-cavernous3, 4 and 6 with 1stDivision of 5Superior orbital f.Tumor (Meningioma)Granuloma=OrbitVascular (diabetes& vasculitis)Infection , granulomaTumor , and trauma3 ,4 or /and 6
202 points you should understands Testing of ocular movement is by 6 cardinal position in conscious patient while in comatose? We use reflex eye movement either by using doll’s head maneuver (oculocephalic ) by rotating the head horizontally to elicit horizontal movement or vertical for eliciting vertical movement or using caloric stimulation (ocular-vestibular) by irrigation of ear by cold (33 c) or warm(44c) water and see response after you are sure that TM is intact.Gaze palsy? When the lesion in the cortex or brainstem above the ocular motor nuclei result in loss of conjugate (yoked) movement of eyes ,no diplopia.
21V nerve (CN- V)It has 3 major division ophthalmic, maxillary, and mandibular.It is sensory nerve of face ,mouth and nasal cavity , it also supply motor and properioception to muscle of mastication.Course : both sensory and motor rootlets originating within pons from 2 separate n. : large sensory and small motor ,both emerge from mid lateral portion of pons------V ganglia in middle cranial fossa------gives rise to 3 main branches ,they exit the cranium through orbital fissure , foramen Rotundum and ovale respectively. the motor component pass through the V gang. Then with mandibular division .CLINICAL PRESENTATION: lesion in V nerveFacial numbness , unilateral loss of corneal reflex, masticators weakness . facial pain and numbness are the hallmark of V nerve lesion as herpes , infiltrative lesions (tumor)Change in taste?? General sensation of mouth and palate are necessary For taste.DD---H . Zoster , trauma especially dental , fracture , neuropathy due to neoplasm ,MS, and idiopathic are common causes in developed countries.Hansen disease is world wide cause of V nerve lesion.
23MRI may be done if above cause s are suspected. there is focal signs. Clinical entitiesTrigeminal neuralgiaIs disabling sever brief paroxysms of pain within CN-V distribution that is worst pain an individual might be experience ,also called tic doulereuxtrigeminal N . Is not diagnosed by any test, it is history diagnosis affecting people in middle age with characteristic sever unilateral pain (with exception ) in distribution of maxillary . Or mandibular Division rarely in ophthalmic division .it is often triggered by cold win ,eating drinking hot or cold ,talking , chewing ,shaving , laughing , or touching the area (triggered zone). typically the pain is intermittent and rarely occur in nightEtiology and pathophysiology; unknown but in majority there is myelin loss in posterior root of V nerve lead to pain, in younger pt. demyelinating disorder should be excluded .Another common causes are : aberrant vascular loop that lengthened in adult life become tortuous and press on the nerveothers are pressure from tumor like Meningioma , acoustic neuromas , AVM or aneurysm ; MS in young ?MRI may be done if above cause s are suspected. there is focal signs.Treatment: several line are availableMedical : by giving carbamazepin 600mg -1200mg/daily to stabilize cell membrane, other approach is gabapentin , pregabalin , phenytoin , baclofen, amitriptylline -----ectSurgical ; indicated if no response to above , it is done by microsurgery decompression of the root , percutaneous radiofreguency rhizotomy or percutaneous trigeminal G. balloon compression ,latter 2 is to destruct V ganglia.
25Herpes zoster V sensory neuropathy It is vesicular skin eruption in dermatome pattern due to reactivation of varicella zoster virus .it is increasingly common with advanced age , immunocompromised pt. as in malignancy and lymphomas . It is mainly involved 1st division with risk of corneal involvement ,abrasion and blindness and risk of post herpetic neuralgia.Antivirus as acyclovir is main step in therapy, MCA infarction is rare complication.V sensory neuropathyV nerve ganglia is main site of pathology probably related to an autoantibody, this why it may associated with other CTD. It starts as numbness and paraesthesia around the mouth progress over months to involve all division unilaterally or bilaterally. ophthalmic division may be spared . Demyelinating disease should be excluded.Sjogren’s syndrome 5th CN nerve involvement is common and seen as apart of widespread sensory ganglionopathy
27Facial nerve VII CNANATOMY (complex) and FUNCTION : the facial nerve have 4 elements: motor supply facial expression muscle, autonomic supplying salivary and lacrimal gland , somatic sensation to EAM, and taste sensation from ant. 2/3 of tongue.COURSE : IT CONSISTS 2 PRIMARY ROOTS ,the larger carry motor fibers originating in caudal pons (motor N.) passing dorsally and up ward twisting over 6th n nucleus and then exit the pons laterally ,the smaller root called nervus intermedius (of wrisberg) contain combination of autonomic (pterygopalatine and submandibular G. ), somatic and taste via chordea tympani fibers(geniculate G.).Peripheral course: both roots exit brainstem to inter the temporal bone with 8th nerve at IEM , then pass into facial canal ,the has it exit out cranium via stylomastoid foramen behind the ear passing through parotid gland that give rise to many branches to supply muscle of face
28Facial nerve lesion or it’s central fibers= above the nucleus level ( voluntary and emotional fibers) results in facial weakness which is divided in to:Upper facial weakness due to lesion affecting upper motor neuron or it’s descending fiber down to the facial nucleus at the pons in which the upper part of face is spared or slightly affected?Causes?Lower facial weakness due lesion affecting lower motor neuron at the pons i.e. lesion at the F. nucleus or the lower final pathways (root ,nerve . NM , or the muscle).Causes? Unilateral or bilateral.Bell’s palsyOne of common distinctive entity in clinical neurology , it is acute unilateral lower facial weakness of unknown etiology ,but it is thought to be associated with edema , entrapment, and resulting ischemia of VII nerve as it passes through facial canal. the specific pathophysiology is unknown: a reactivation of herpes simplex and varicella –zoster virus latent infection within Gen. ganglia is hypothesized ,this together with edema provide basis for treatment
29Clinically the pt. presented over hours or days as weakness at any age ,the family or friend noticing it as an asymmetry in face and inability to close the eyes, difficulty in holding saliva ,food and fluids in affected side, less common as taste abnormality and hyperacusis.Preceding pain behind the ear is common initial problem.On examination there will be lower facial weakness( facial asymmetry, absence wrinkled in affected side , epihporia ,inability to close the eyelid, and bell’s phenomenon? ).DD? Muscle fiber disease( MD) , NM- disorder, Bell’s , drug induced , Ramsy hunt , sarcoidosis , Gullian barre syndrome , diphtheria , and brain stem disorder (like tumor ,ischemia ,ms) , and traumatic.Bilateral causes ? Unilateral causes?Recurrent ? Melkersson –Rosenthal (AD) ,Hereditary pressure palsy ( more common with Ulnar and or peroneal) as an allelic dis. With charcoat Marie toothTreatment of Bell’s p. : controversial ? Good prognosisSteroid may reduce duration of paralysis and risk of squealy (within 1st 7 days of onset) . It is given as 1mg/kg in divided doses for 5-6 days with tapering over 4-5 days .There is some evidence that combination with acyclovir may speed the recovery without affecting overall prognosis.General supportive care is necessary to prevent corneal damage from unclosed eye therefore night eye patching and artificial tear are important.Recovery : most patient will have recovery within 3 weeks and some may needs 3-6 months after the onset. The overall prognosis is good(80-85% recover completely ).the bad prognosis signs complete paralysis , persistent pain , axonal type
30Facial myokymiaSubtle continuous ,undulating movement of facial M. it is usually unilateral confined to 1 and 2 facial m. and sometimes associated with weakness and contracture. It is most likely related to antibody against subtype of k voltage channel ; also seen in Isaac syndrome (rigidity and Myotonia without pain ,SPS-stiff person syndrome)DD ---MS , rarely due to intrinsic brainstem GliomaHemifacial spasm : intermittent ,rapid and irregular colonic twitching facial movement, typically it start near the eyes and spreads to other ipsilateral facial m. specially perioral area and may persist during sleep , preceding VII nerve lesion is rare.Etiology : unknown but vascular loop is presumed a main underlying pathophysiologic mechanism less frequent cause are tumor and infection .Medical treatment : Botox injection (botulism toxins) , carbamazepin, clonazepamSurgical: decompression.
33VIII NERVE :Dizziness and vertigo CRANIAL NERVE IX & X: Function and anatomy: they are originating from medulla O. passing together with the accessory nerve at the base of skull ---exit the cranium at jugular F.They are responsible for swallowing and voice + other functionsLesion : either lower motor neuron affecting the lower motor neurons at the MO or the roots , nerves or NM, and muscle (bulbar palsy) or upper motor which should be bilateral, lesion above the nuclei of XI&X =corticobulbar or it’s origin at the cortex ( pseudo-bulbar palsy) .
34Pseudobulbar-upperBulbar-lowerPathology:Dysartheria: spastic =hot potatonasaldysphagiaJaw jerk---briskNorma or absentEmotional liability---Gag----exaggerated or normalUsually absentTongue spasticFlaccid with atrophy and fasciculationCause: MS, multiple strokes , vasculitis , infection as encephalitis, MND(PLS) , tumor or any bilateral lesionsBrain stem: infarction, MND, tumorRoot and nerve –GBS, diphtheria sarcoidosis, basal infiltration with infection or malignant cells (jugular f. syndrome)NM---MGMuscle---myositis
35Cranial nerve XIIt is primarily a motor innervations of sternomastoid and trapezius muscle in the neck and back,in contrast to other CN ,it’s lower motor nucleus originating from upper 5 cervical spinal cord segments (within lat. Ant. Gray column) forming the spinal seg. Of nerve which ascends up near midline entering the cranium through F. magnum to unite with cranial portion of the nerve which is originated from the caudal portion of N. ambiguus at the medulla O. which runs together with Vagus at base of skull to exit the cranium at jugular foramen entering the neck with close proximity to ICA and internal JV , to supply trapezius (proximal portion) and SCM (sternocleidomastoid) .TZ is responsible for shrugging of shoulder and arm abduction above the horizontal—winging is common when arm is abducted( in contrast to L. thoracic nerve palsy) while SCM is for turning of head to opposite side .
36C/F :dropping of shoulder with pain some times and mild scapular winging, SCM is spared when lesion is high in the neck while both are affected in IC lesion.SCM weakness------difficulty in turning the head to opposite sideCAUSES OF XI NERVE LESION : commonly due to lymph node biopsy in the neck, ICA surgery and jugular vein canulation, motor neuron affection by polio , syrinx and MND. , basal Meningioma and tumor at base of skull or jugular F.DD : it should be differentiated from plexopathy.
37Hypoglossal nerve=XII Supplies the all extrinsic and intrinsic tongue muscleIt originates from the hypoglossal nucleus in the floor of 4th ventricle ,rootlets from lat. Portion of MO unite together to form XII nerve ---base of skull then exit the cranium via XII foramen in posterior fossa.Outside cranium passes in close proximity to Carotid artery make it vulnerable to any lesion affecting C.A. As in carotid endarterectomy or dissection.Clinical presentationbilateral lesion---difficulty in protrusion of tongue , with difficulty in speech and swallowingUnilateral lesion----resting position there is wasting in side affected with fasciculation ,when tongue protruded ;it is deviated to affected side(to weak site)Causes:LOWER TYPE AS INAt brain stem level :MND, polio, syringobulbia , intra-medullar tumor , and brain stem infarction .At base of skull-----neoplasm , metastasis , Meningioma , neuromas , chordoma , glomus jugulare tumorNeck---trauma , carotid dissection and surgery ,radiation therapyUPPER MOTOR TYPE :unilateral(uncommon) --- deviation of tongue opposite to side of lesion while bilateral-----seen in Pseudo bulbar palsy