Cranial Nerves Flashcards
what can cause loss of smell
damage to CN I olfactory: head injury tumours parkinsons seizures
upper quadrantinopia indicates a problem in
temporal lobe
lower quadrantinopia indicates a problem in
parietal lobe
where is problem if homonymous hemianopia
optic tract (after chiasm)
common cause of homonymous hemianopia
posterior cerebral artery infarct
what do retinal/local eye lesions cause
scotoma (blind spot)
peripheral vision loss (‘tunnel vision’)
hallmark of optic nerve lesion
unilateral visual loss
central or paracentral scotoma
loss of papillary light reflex
what part of autonomic nervous system causes pupil dilatation
sympathetic
‘running in the dark’
what part of autonomic nervous system causes pupil constriction
parasympathetic
what nerve causes pupillary constriction
short ciliary nerve
what is Leber’s hereditary optic neuropathy
unilateral/bilateral optic nerve neuropathy developing over several weeks in young healthy men
mode of inheritance of leber’s hereditary optic neuropathy
mitochondrial DNA mutations
optic disc pallor
optic atrophy
causes of optic atrophy
nerve infarction follows papilloedema inflammation (MS, syphilis, LHON)
clinical manifestations of pupillary defect
illuminated pupil not reacting to light
loss of contralateral consensual reflex
Triad of:
unilateral pupillary constriction
ptosis + enophthalmosis (sunken eye)
ipsilateral anhidrosis (loss of sweating)
horner’s syndrome - interruption of sympathetic supply in face
causes of horner’s syndrome
demyelination
vascular disease
tumour
what does diplopia indicate
weakness to one or more extraocular muscles
signs of CN III nerve palsy
unilateral complete ptosis
eye facing DOWN and OUT
fixed, dilated pupil (if pupil spared, parasympathetics not affected)
signs of CN IV nerve palsy
supplies superior oblique muscle
torsional diplopia when attempting to look down (descending stairs)
head tilted away form that side
signs of CN VI palsy
supplies lateral rectus
convergent squint with diplopia when looking to the side of the lesion
sign of CN V lesion
diminution of corneal reflex (don’t blink when eye touched)
unilateral sensory loss to face, toungue
jaw deviates to side of lesion as mouth opens
paroxysms of knife like/electric shock pain lasting seconds and triggered by touch (washing, shaving, cold wind, eating)
trigeminal neuralgia
treatment for trigeminal neuralgia
carbamazepine
signs of UMN lesion of facial nerve
weakness on lower part of face on opposite side (forehead spared)
signs of LMN lesion of fcial nerve
ipsilateral weakness of all facial expression muscles
most common cause of CN VII nerve palsy
Bell’s palsy
other causes of CN VII nerve palsy
trauma otitis media ramsay-hunt syndrome (herpes zoster) brain stem lesion acoustic neuroma parotid tumours
bell’s palsy is acute/chronic
acute
what virus is associated with bell’s palsy
herpes simplex
treatment of bell’s palsy
steroids within 72 hours onset protect eye (dark glasses, artificial tears)
hallmark of ramsay-hunt syndrome
painful vesicular rash on auditory canal, pinna, tongue, palate or iris
treatment for ramsay-hunt syndrome
prednisolone (if <72 hours onset)
acyclovir
nystagmus on performing hallpike manoeuvre
benign positional vertigo
Meniere’s disease clinical manifestations
vertigo >20mins (possible nausea/vomiting)
sensorineural hearing loss
tinnitus
what drugs can cause vertigo and hearing loss
gentamycin
furosemide
cisplatin
in hypoglossal lesion, tongue deviates towards/away from lesion
towards
