cranial nerves: clinical Flashcards
what would a fracture to the cribiform plate result in?
anosmia - loss of sense of smell
most common cause of anosmia?
URTI
head injuries e.g. shearing forces / basilar skull fracture
how will you fracture the cribiform plate?
from anterior cranial fossa trauma
what can fracture to the cribiform plate also result in?
leakage of CSF through the nose (rhinorrhoea)
what can rhinorrhoea lead to?
brain infections, including meningitis
what is common with viral / allergic rhinitis?
transient olfactory impaiment
what can fracture to the optic canal damage?
the optic nerve
what does damage to the optic nerve result in?
loss to papillary constriction
complex pathway from retina to visual cortex - occipital lobe
Different lesions to optic nerve give rise to?
different patterns of visual loss:
e.g. optic neuritis, pituitary tumour, stroke
pressures on the optic pathway result from?
raised intracranial pressure / loss of blood from the central artery of the retina
what can pressures on the optic pathway result in
blurring of the margins of the optic disc and subsequent visual field defects
what is swelling of the optic disc? result from?
papilloedema
from pressures on the optic pathway
causes of compression on the optic pathway? leading to?
pituitary adenomas / carotid aneurysm
cause visual field defects
lesions to oculomotor nerve results in?
diplopia (double vision) ptosis (drooping eyelid) pupillary dilation (absent papillary light reflex)
what can damage to oculomotor nerve be a result of?
cavernous sinus thrombosis
aneurysm (of the posterior cerebral / superior cerebellar artery)
raised intracranial pressures
diabetes / hypertension (pupil sparing)
is trochlear nerve (CN IV) usually damaged?
rarely paralysed alone
how can you usually correct damage to trochlear nerve?
slight tilt of the head
what is the most common cause of trochlear nerve (IV) damage?
head injury - most common cause of acute injury
OR
raised ICP can stretch nerve
what can damage to trochlear nerve (IV) result in?
diplopia (double vision) - worse on downward gaze e.g. reading / walking downstairs
(eyeball can become slightly adducted and superiorly rotated)
what is a cause of trochlear nerve (IV) damage in children?
congenital nerve palsy
what can result in damage to the trigeminal nerve (V)?
trauma, tumour, aneurysms, meningeal infections, shingles, trigeminal neuralgia