18 Cranial Nerves Flashcards
(18 cards)
1-Olfactory
Sensory (smell), Head trauma, Sinus disease, Parkinson’s
The only cranial nerve that doesn’t pass through thalamus before cortex
2-Optic
Sensory (vision)
Pupillary light reflex: afferent 2 goes to midbrain -> efferent 3 comes back to both eyes
First shine separately: Check Afferent (2)
Then shine between two: Check if one is damaged (constricts less or even dilates) = Marcus gun -> Optic Neuritis MS, Ischemic optic neuropathy AION, Optic nerve compression tumor, Retinal Detachment, Central Retinal artery occlusion, Trauma, Optic atrophy (glaucoma)
Visual acuity ( Snellen chart )
Visual Field (Confrontation)
Fundoscopy
3-Oculomotor
Motor (eye movements, lid elevation, miosis (parasympathetic), accomodation) : paralysis -> ptosis, down out, diplopia, dilated pupil, loss of accommodation
Pupil involved (Peripheral): Compressive like aneurysm posterior communicating artery/ Weber, basilar artery aneurysm, cavernous sinus mass, tumor, uncal herniation -> Emergency surgery
Pupil not involved (central): Ischemic due to DM, HTN, Atherosclerosis, Giant cell, Vasculitis
Variable: Inflammatory: MS, Sarcoidosis, Tolosa Hunt syndrome, Vasculitis
Infectious: Meningitis, Syphilis, Herpes zoster, Lyme, Mucormycosis
Trauma
Neoplastic: Lymphoma, leukemia
Migraine, Iatrogenic, Congenital
Unilateral ptosis: Horner, levator palpebrae superioris, 3rd nerve palsy
Unilateral ptosis + weakness hand: T1 lesion, horner syndrome
4-Trochlear
Motor (Superior Oblique = Down intort abduct ) Nucleus contra lateral eye effected (unique), if Peripheral ipsilateral (more common), tilts head away from affected eye ,
3 step test: affected eye has hypertropia which worsens with looking or tilting ipsilateral
Problems reading and walking down stairs (vertical diplopia)
*all cranial nerves control ipsilateral except 4
5-Trigeminal
Facial sensation ( ophthalmic, maxillary, mandibular +Cornea, oral nasal mucosa, general sensation ⅔ tongue ) mastication muscles (Mandibullar) -> masseter, temporalis, petrygoid
corneal reflex, jaw reflex
Findings:
Peripheral, Gasserian ganglion ( all branches), Pons ( can have 7 palsy ) , MS, CP angle tumor/acoustic neuroma (5,7,8), Lateral pontine syndrome (ipsilateral face numb, contralateral body temp)
Trigeminal Neuralgia, Hutchinson sign ( Shingles - urgent ophthalmologic refer )
6-Abducens
Motor (lateral rectus)
DD: Raised ICP (most common), diabetic mononeuropathy, Medial pontine syndrome, tumor base skull, cavernous sinus syndrome (3,4,5 (V1,V2, 6, facial infection thrombosis, urgent IV Ab)
Unilateral: Microvascular (DM,HTN), Raised ICP(early, tumor, hydrocephalus, IIH), Brainstem (Stroke, MS, Pontine tumor), skull base lesion, cavernous sinus lesion, trauma
Bilateral: symmetrical Raised ICP (most common, midline tumor, hydrocephalus, IIH), meningitis, pontine stroke MS, Wernicke,
Isolated acute 6th nerve palsy: Microvascular (diabetic), benign, aspirin, metformin, ace, review in 1 month
7- Facial
Facial expression muscles, Taste ⅔ anterior, parasympathetic (lacrimation, salvation) Corneal reflex (motor), Stapedius reflex
LMN (peripheral): Ipsilateral, Forehead involved, Bell’s palsy, Acoustic neuroma, Ramsy hunt syndrome, otitis media, parotid tumor, trauma, PONS stroke (millard gubler) guillain barre, CIDP, miller fisher, lyme (bilateral), HIV, TB, sarcoidosis, Bilateral Acostic neuroma in neurofibromatosis 2, DM
may have taste loss, hyperacusis
UMN (Central): Contralateral, Forehead Spared, Stroke cortex/internal capsule (may have limb weakness), MS, Brain tumor, Trauma
Bell’s palsy
idiopathic, viral (HSV), sudden, 7th palsy, ear pain, Hyperacusis, loss of tearing ( lesion before geniculate), ⅔ anterior tasting (stylomastoid foramen dmg), drooling when they try to eat, inability to close eyes/smile,
Investigation: Clinical diagnosis, rule out stroke, ramsay hunt, tumor, lyme, MRI if atypical features or poor recovery
50mg prednisolone started within first 3 days, acyclovir, artificial tear, eye patching, physical therapy
70% complete recovery without treatment
Ramsy hunt syndrome
Ramsy hunt syndrome: 7th palsy + VZV vesicles, invading geniculate and 8th nerve as well (ear pain, hearing loss, vertigo, tinnitus) , oral aciclovir+Prednisolone
if it gets ophthalmic branch of trigeminal, treatment is same.
Hutchinson sign: VZV on nose, ophtalmology refer emergent
8-Vestibulo Ocular
Sensory, hearing and balance,
Cochlear: Hearing: Finger rub/whisper test, Rhinne, Weber
Vestibular: Balance, spatial orientation -> Vertigo, imbalance, Nausea, Nystagmus: Romberg test ( vestibular or proprioceptive), Marching test, spontaneous nystagmus, Heat impulse test (abnormal if eyes move away with head then do a fast corrective saccadic move)
Lesions: Acoustic neuroma/Vestibular schwannoma, Menier, Labrynitis, Vestibular neuritis, ototoxic drugs, MS, AICA infarct
*Vertigo, imbalance, nausea, and nystagmus can be present in both Peripheral 8 and Cerebellum/brainstem lesion. Ataxia, vertical nystagmus, dysarthria, limb ataxia like dysmetria, facial palsy is more cerebellum while spinning sensation, horizontal nystagmus, hearing loss, tinnitus, HIT abnormal and Romberg + is more peripheral 8.
Rinne and Weber test
Rinne test: tuning fork placed on mastoid until no longer heard, then move next to ear canal, ask if they can still hear it.
Positive test (NL or sensorineural): Air conduction is better than bone conduction
Negative: Bone conduction better ( Conductive deafness )
Weber test: Fork in the middle of forehead, conductive to affected side, sensorineural to good ear (contralateral side)
Rhine positive Right, Weber lateralize to Left: Right Sensorineural hearing loss
Rhine negative Left, Weber lateralizes to left: Conductive
9-Glossopharyngeal
Mixed,
Motor: Stylopharyngeus: Elevates pharynx during swallow and speech -> overlaps with 10 in Dysphagia, problem in swallowing
Sensory: Taste ⅓ posterior, upper pharynx, middle ear tube salivation ( parotid), carotid body baron receptor, chemo receptor -> Labile BP, syncope
Reflex: Gag reflex 9 -> 10
Parasympathetic: Parodi gland
Lesions: Lateral Medullary syndrome/ Vernet syndrome, Glossopharyngeal neuralgia, Tumor (parotid, nasopharyngeal, glomus jugulare ), Iatrogenic (carotid endarterectomy )
10-Vagus
Mixed
Motor: swallow/speech -> Ask to say aah: Soft palate fails to rise on the affected side Uvula deviates away from lesion
Voice (recurrent laryngeal,
Sensory: Larynx, thorax, abdomen viscera
Gag Reflex, Cough reflex
Parasympathetic: Heart, lung, digestive tract
11- Accessory
Motor, Shoulder shrug (trapezius), Head rotation(contralateral SCM)
12-Hypoglossal
Motor, Tongue movements: Stick out tongue, move tongue from side to side
UMN: away from the lesion,
LMN: towards the lesion, fasciculation atrophy
Causes: Brainstem stroke, tumor, trauma, MND (ALS)
Reflex
Pupil to light: 2>3
Corneal reflex + tear : V1 > 7
Jaw jerk: V3-V3
Gag + carotid sinus : 9 > 10
*3,4,6 all cross superior orbital fissure along with V1. V2 foramen rotundum, V3 foramen ovale. 7,8 internal auditory meatus. 9 10 11 jugular foramen, 12 hypoglossal canal
5: Mastication muscles, deviation jaw to weak side, facial sense
*all cranial nerves control ipsilateral except 4
*3,4,6 all cross superior orbital fissure along with V1. V2 foramen rotundum, V3 foramen ovale. 7,8 internal auditory meatus. 9 10 11 jugular foramen, 12 hypoglossal canal
5: Mastication muscles, deviation jaw to weak side, facial sense
*all cranial nerves control ipsilateral except 4
Some syndromes:
Vestibular shwanomma/Acostic neuroma:
Jugulare foramen syndrome/Vernet:
Collet sicard syndrome:
Cavernous sinus syndrome/Tolosa hunt:
Medial Medullary syndrome:
Lateral medullary syndrome:
Petrous apex syndrome:
Orbital apex syndrome:
Superior orbital fissure syndrome:
Ramsy hunt Syndrome:
Some syndromes:
Vestibular shwanomma/Acostic neuroma: 7,8+5
Jugulare foramen syndrome/Vernet: 9,10,11
Collet sicard syndrome: 9,10,11,12
Cavernous sinus syndrome/Tolosa hunt: 3,4,5 (V1,V2),6
Medial Medullary syndrome: 12
Lateral medullary syndrome: 9,10+5
Petrous apex syndrome: 5+6 (V1 V2)
Orbital apex syndrome: 2,3,4,5 (V1,V2)
Superior orbital fissure syndrome: 3,4,5 (V1,V2)
Ramsy hunt Syndrome: 7,8
