Cranial Nerve Disorders Flashcards
what cranial nerves have special senses?
> olfaction
vision
taste
hearing
what controls the muscles of mastication?
trigeminal nerve (V)
what controls the muscles of the larynx and pharynx?
vagus (X)
what cranial nerves have parasympathetic innervation?
> oculomotor (pupil constriction)
Facial nerve
glossopharyngeal (parotid)
vagus (thoracic and abdomen organs)
what does the facial nerve supply with parasympathetic innervation?
> lacrimation
> salivation: submandibular and sublingual glands
why would you only do the corneal test if the facial nerve is working?
it is an uncomfortable test and if the facial nerve is not working the patient cannot blink (showing the reflex is working). it will not tell you anything about the trigeminal nerve
how would you test vestibular function?
> dix-hallpike manoeuvre
> untenbergers test
in the pupillary light reaction what is the afferent component?
II: optic nerve
what is the efferent component in the pupillary light reaction?
III oculomotor nerve
what is the afferent component of the corneal reflex?
trigeminal V
what is the efferent component of the corneal reflex?
VII facial nerve
in the jaw jerk reflex in the trigeminal nerve the efferent or afferent component?
both!
what is the afferent component of the gag reflex?
glossopharyngeal nerve IX
what is the efferent component of the gag reflex?
vagus nerve X
where do the oculomotor and trochlear nuclei lie?
in the mid brain
where do the trigemina, abducent and facial nerve lie?
in the pons
where does the vestibulocochlear nerve lie?
at the pontomedullary junction
what nerves lie in the medulla?
> glossopharyngeal
vagus
accessory
hypoglossal
what does an unusual combination of cranial nerve signs suggest?
there is chronic or malignant meningitis
what do pure motor signs suggest?
myasthenia gravis
what can damage cranial nerves within the brain?
> ischaemia
> tumour
what can damage cranial nerves when crossing the subarachnoid space?
meningitis
where can cranial nerves be damaged?
> within the brain
crossing the subarachnoid space
outside the skull
what happens to the optic nerve in optic neuritis?
there is demyelination
describe the symptoms and signs seen in optic neuritis
> monocular visual loos > pain on eye movement > reduced visual acuity > reduced colour vision > swollen optic disc
what condition is optic neuritis associated with?
multiple sclerosis
what happens if there is loss of parasympathetic input to the eye (complete third nerve palsy)?
there is a fixed dilated pupil
does the pupil dilate or constrict with the sympathetic system?
it dilates
what can cause dilated pupils?
> youth > dim lighting > anxiety > mydriatic eye drops > amphetamine > third nerve palsy > brain death
what can cause constricted pupils?
> old age > bright light > miotic eye drops > opiate overdose > horners syndrome
what is horners syndrome?
damage to the sympathetic chain causing ptosis and hydrosis
name some eye movement disorders
> isolated third nerve palsy > isolated fourth nerve palsy > isolated sixth nerve palsy > combination of above pasly's > supranuclear gaze palsy > nystagmus
describe microvascular third nerve palsy
caused by diabetes and hypertension. it is painless and the pupil is spared
describe compressive third nerve palsy
caused by posterior communicating artery aneurysm and raised ICP. this is painful and the pupil is affected.
what can cause isolated 6th nerve palsy?
> idiopathic
diabetes
meningitis
raised ICP
what can cause nystagmus?
> congenital > peripheral vestibular problem > central vestibular/brainstem disease > cerebellar disease > toxins
describe the attacks in trigeminal neuralgia
they are paroxysmal attacks of lancinating pain
what causes trigeminal neuralgia?
vascular loop compression of the 5th nerve in the posterior fossa
how is trigeminal neuralgia treated?
with carbamazepine
is bells palsy upper or lower motor neuron?
lower motor neuron
describe bells palsy facial weakness
> unilateral face weakness
> eye closure often affected, risk of corneal damage
what can bells palsy be preceded by?
pain behind the ear
what is bells palsy treated with?
steriods
how is the forehead affected in an upper motor neuron condition?
it can still move at both sides as it bilaterally innervated
how is the forehead affected in a lower motor neuron condition
half of it is affected and paralysed
describe vestibular neuronitis
> sudden onset
disabling vertigo
vomiting
gradual recovery
what is dysarthria?
disordered articulation, slurring of speech
what is dysphagia?
difficulty swallowing
in what condition can both dysarthria and dysphagia occur?
in bulbar and pseudobulbar palsy
is bulbar palsy upper or lower motor neuron?
lower
is pseudobulbar palsy upper or lower motor neuron?
upper
what signs and symptoms are seen in pseudobulbar palsy?
> dysarthria > dysphonia > dysphagia > spastic immobile tongue > brisk jaw jerk > brisk gag reflex
describe the lesion in bulbar palsy
> bilateral lower motor neuron affect IX-XII
what signs and symptoms are seen in bulbar palsy?
> wasted fasciculating tongue > dysarthria > dysphonia > dysphagia > BEWARE OF FEEDING THESE PATIENTS
