Cranial Nerves Flashcards
Explanation of procedure
WIPER QQ
I’d like to examine the nerves in your head and neck, this will involve an assessment of the muscles, sensation and reflexes.
Potential findings around bedside
-what could this mean?
Hearing aids, glasses
-CN VIII issues (Meniere’s? - sudden vertigo, tinnitus, hearing and balance changes)
Walking aid
-Parkinsons, stroke, cerebellar disease, MG
Visual aid
-Visual prisms, occluders => squint?
Medications
Potential findings in patient from bedside
Speech abnormalities
-IX or V issues
Face asymmetry
-VII palsy?
Eyelid abnormalities
-ptosis => III issue?
Pupillary abnormalities
-mydriasis (dilated pupil) => III issue?
Squint
-III, IV, VI issue
Limbs
-any spasticity, weakness, wasting, tremor, fasciculations
Olfactory nerve
- how to test
- potential reasons
Ask about changes in smell
Blocked nose Head trauma (olfactory nerves torn) Genetics - Kallmans Prodromal PD COVID
Optic nerve
- screening
- inspection
Do you have any issues with vision
Do you normally wear glasses/contacts, please wear them for the examination
Inspection - pupil size, shape, symmetry
- size with respect to lighting
- peaked pupils - globe trauma
- anisocoria (judge in relation to lighting) - III palsy, Horners?
- ptosis - III, Horners?
- lid retraction, exopthalmos - Graves eye disease
Optic nerve - visual acuity
- what are the 3 visual acuity tests
- how would you do them
- documentation
- causes of decreased visual acuity
Cover 1 eye at a time
Visual acuity - Snellen (distant), reading a letter (near), Ishihara (colour)
Snellen - 6m
- go down lines until 2+ mistakes => record acuity as previous line
- 2 wrong => current line (-2)
- note down with glasses/unaided
- if pinhole available, assess for reduced acuity due to refractive error
Finger counting => hand mv => detecting light
Non CN pathologies
-refractive error => corrected with pinhole
-cataracts, corneal scars, macula degeneration
CN related - issue along optic pathway
-optic neuritis?
Ishihara plates - ask patient to read no
Max score = 13/13
Congenital Acquired -optic neuritis - MS? -VitA deficient (xeropthalmia => keratomalacia) -chronic solvent exposure
Optic nerves - visual fields
- inattention (not part of cranial nerve exam)
- fields
- blindspot
Cover 1 eye at a time for fields and blindspot
Visual fields - inattention, fields, blindspot
Inattention - test all 4 quadrants for nondom parietal lobe
- patient focuses on your nose
- hold your hands out in visual field peripheries
- ask patient to point at the fingers that are wiggling
Fields - cover same eye as patient, test all 4 quadrants
- use red neurotip/fingers equidistant between you and patient
- move neurotip from peripheries into centre from corners
- ask patient to tell you when they can see the red neurotip
Bitemporal hemianopia - chiasm compression
Homonymous - posterior to optic chiasm (stroke, tumour, abscess)
Scotoma - reduced central vision surrounded by normal vision (MS, diabetic maculopathy)
Monocular loss - optic nerve issue (central retinal artery occlusion, retinal detachment)
Blindspot - cover same eye as patient
- patient focuses on your nose
- hold red neurotip equidistant between you and patient from midline => lateral mv
- ask patient to say when they lose and see red => compare with own
Increased blindspot - larger optic disc => opthalmoscopy
Oculomotor, trochlear, abducens
- inspection
- eye movements
Ptosis - III (medical palsy spares reflex), Horners, MG?
-surgical - affects reflexes + ptosis (post comm aneurysm)
Extraocular mv - cover same eye as patient
-follow finger with eyes in H
Restricted mv, nystagmus (cerebellar), double vision, pain?
CN III palsy - down+out (sup, med, inf rectus, inf oblique)
CN IV palsy - up+in (sup oblique) => head tilt to normal side
-vertical diplopia => head tilt down
CN VI - adduction
-horizontal diplopia worsened by looking at affected side
Fundoscopy of optic disc
Optic reflex
-how would you assess this
Direct => ipsilateral constriction (afferent III)
Consensual reflex => contralateral constriction (efferent III)
Swinging light => both constrict
-RAPD (dilation) => MS?
Accommodation - look quickly between distance and your finger => bilateral constriction, convergence
Trigeminal
- inspection
- motor function
- sensory function
- location of dermatomes
- reflex
Inspect temporalis, masseter wasting
Palpate when clenched, unclench
Open jaw => ipsilateral deviation (medlat pterygoids)
Open against resistance
I will test your sensation with a disposable pin. It will be sharp but not sharp enough to hurt you.
Close eyes => bilateral opthalmic, maxillary, mandibular sensory testing with cotton
-assess for equal bilateral sensation
V1 - nose midline, under eyes, vertex of head
V2 - lateral nose, cheeks, upper lip
V3 - lower lip, sides of face, NO EAR OR NECK INVOLVEMENT
-always test mental foramen - numb chin syndrome (all cancers can spread to oromaxfax)
Jaw jerk - tendon hammer against chin => UMN exaggerated closure
Corneal reflex - blink when cornea touched
-can assess direct and consensual (V1 => VII)
Facial
- inspection
- motor
- motor function
Inspect - asymmetry in forehead, nasolabial folds, mouth angles
Close eyes - resist me opening them
Raise eyebrows - stop me pushing them down
Puff out cheeks - stop me pushing them in
Whistle
Biggest smile
LMN issue - weakness of all ipsilateral muscles (Bell’s palsy)
UMN - forehead sparing ipsilateral weakness (stroke)
Vestibulocochlear
- hearing
- vestibular function
Any changes in your hearing or balance?
Balance - march on spot
Cover 1 ear, whisper number from 2 distances => repeat in other ear
512Hz Rinne - air > bone POSITIVE :) -Negative => conductive loss Weber - equal lateralisation :) -louder in conductive side -quieter in sensorineural side
Rinne and Weber
Turning test, Hallpike done mainly in ENT
Glossopharyngeal and Vagus
- inspection
- actions
Ahhh => uvula deviation away from lesion, palate asymmetry
-vagus lifts palate, uvula
Cough => speech => thickened fluids => water
Water drinking => swallow
Cough - weak, non explosive (vagus issue?)
Gag reflex - only done in comatose ICU
Accessory, hypoglossal
- inspections
- actions
Inspection - DWARFS
Shrug shoulders vs resistance
Turn head vs resistance
Inspection - furrows, atrophy
Stick tongue out => deviation towards lesion (overpowered genioglossus on ok side)
Tongue pushes against cheek vs resistance
Further investigations
Examination
- upper, lower limbs to assess for any UMN, LMN issues
- fundoscopy, Amsler grid if there are any visual concerns
- Dix Hallpike - vestibular issue
- Head impulse test - peripheral vestibular issue vs central vestibular issue
Tests
- blood tests for diabetic
- hearing test
Imaging
-MRI head if there are any concerns
