cranial nerves Flashcards
role of CN II
Vision and direct pupillary light reflex
lesion in CNII
Blindness, loss of direct pupillary light reflex
role of trochlear IV
superior oblique, intorts eye and rotates down and out
lesion in CN IV
cant look at their nose
weakness of down gaze
role of CN III/Oculomotor
medial rectus inferior oblique inferior rectus superior rectus LPS
lesion in CN III
dialted fixed pupil
ptosis
ipsilateral gaze fixed
DOWN and OUT
Role of CN V tirgeminal
opthalmic
maxillary
mandibular
lesion in CN V
loss of sensation in the face, eyes, nose and mouth
loss of corneal reflex
deviation of the jaw to the ipsilateral side
role of CN VI abducens
lateral rectus
lesion of CN VI
esotropia
role of VII facial
facial movement, taste, lacrimation, salivation
lesion of CN VII
facial palsy
loss of blink
loss of taste from the anterior 2/3 of the tongue
role of CNVIII vestibulocochlear
balance
Hallpike -> BPPV
unterberger
hearing
rinne’s and weber’s
lesion of CN VIII
vertigo, tinnitus, and deafness
role of CN IX, glossopharyngeal
taste
salivation
swallowing
lesion of CN IX
Loss of pharyngeal and gag reflex
loss of taste from posterior third of tongue
role of CN X- vagus
larynx and swallowing
lesion of CN X
dysarthria
- deviation away from side of lesion
- Lesions of recurrent laryngeal branch cause ipsilateral vocal cord
paralysis with dysphonia and a weak cough.
Parasympathetic autonomic fibres travel in the vagus nerve to the
respiratory, GI, and cardiovascular systems.
role of CN XI - accessory
larynx and muscle in the neck
lesion of CN XI
difficulty in turning the neck
drooping shoulder
CN XII role hypoglossal
tongue movement
lesion of CN XII
ipsilateral tongue paralysis
causes if CNIII palsy/ oculomotor nerve palsy
- diabetes mellitus
- vasculitis e.g. temporal arteritis, SLE
- false localizing sign* due to uncal herniation through tentorium if raised ICP
- posterior communicating artery aneurysm
— pupil dilated
— often associated pain - cavernous sinus thrombosis
- Weber’s syndrome: ipsilateral third nerve palsy with contralateral hemiplegia -caused by midbrain strokes
other possible causes: - amyloid, multiple sclerosis
Causes of anosmia
viral infections
head injury
IPD
alzheimers
- > refsum
- > olfactory groove meningioma
- > superficial siderosis
- > kallman’s syndrome (anosmia + hypogonadism + X-linked recessive)
- > paraneoplastic disorders
- > Sjogrens
monocular field defect
ocular, retinal, or optic nerve disorders.
cosntricted fields
glaucoma
chronic pailloedema
homonymous hemianopia
site of lesion
aetiology
optic tract
optic radiation
occipital lobe
stroke
tumour
junctional scotoma
site of lesion
aetiology
junction of optic nerve and chiasm
tumour
tonic pupil (Adie’s)
test
Dilated pupil constricts slowly to accommodation.
Unreactive to light but will constrict on prolonged and intense illumination. Vermiform movements visible on slit lamp
generalised areflexia
0.125% pilocarpine constricts pupil
monocular diplopia causes
refractive error cataract media opacity macular disease visual cortex disorder
horizontal diplopia causes
weakness of medial rectus or lateral rectus
what is jerk nysatgmus
eye followed by a corrective fast phase
what is peripheral nystagmus
Unidirectional fast phase beating away from affected labyrinth
Associated with severe vertigo, vomiting, nausea
Amplitude increases with gaze towards the direction of the fast phase
Various components—horizontal, torsional, vertical
Suppressed by fixation (Fresnel goggles remove fixation)
central vestibular nystagmus
Uni- or multidirectional
Mild symptoms. Other neurological signs, e.g. disconjugate eye movements, pyramidal signs
May be gaze-evoked
No change with fixation
what is downbeat nystagmus
- present in the primary position
- accentuated on lateral gaze
due to distrubance of vestibulocerbellum cause by arnold-chiari malformation, cerebellar degeneration
upbeat nystagmus
- present in primary position
- due to lesion in the tegmental grey matter of brainstem
- causes - MS, vascular, cerebellar degeneration
CNVIIII glossopharyngeal
Taste fibres from posterior third of the tongue.
General sensation tympanic membrane, mucous membranes from
posterior pharynx, tonsils, and soft palate.
Afferent part of the gag reflex.
what type of lesion is required to witness significant dysarthria
bilateral lesion
what is pseudobulbar palsy
disruption of both the right and left corticobulbar fibres supplying the motor nuclei of the brainstem
results in a spasti. dysartria, slow facial movements, emotional lability due to the loss of the connections from the frontal cortec to the brainstem that suppress emotional output
facial, palatal and jaw reflexes are brisk
causes of bilateral UMN causinf dysarthria
MS MND Bilateral subcortical ischaemic lesions/stroke progressive supranuclea palsy central pontine myelinolysis
What is bulbar palsy
LMN lesions from damage to the motor nuclei of the 7, 10, 12
speech is slurred, indistinct, labial and lingual sounds are affected
nasal quality due to soft palate
nasal regurgitation with choking and aspiration
tongue wasted and may fasciculate
absent gag reflex, hoarse voice weak cough
causes of LMN lesions causing bulbar palsy
GBS MND Medullary tumours syringobulbia subacute/chronic infective poliomyelitis
speech in parkinsons
low volume monotonous trails off
festinating gait
speech in chorea
hyperkinetis
loud and harsh, intonation is variable
short, breathless sentences
speech in athetosis
athethoid cerebral palsy
loud and slow
dystonic speech
consonants are indistinctly pronounced
what is ataxic dysarthria and causes
cerebellar lesions
slow and slurred with abnormal long pauses between syllables
rapid side to side movements of the tpngue
scanning with broken up into syllables
causes
MS
Vascular lesions ie infarcts and haemorrhages
tumours
inherited ataxias - spinocerebellar dysarthrias
alcoholic cerebellar degeneration
