CN Questions Flashcards
I - Olfactory
Trauma
Frontal lobe tumour
Meningitis
II - Optic
Monocular blindness: MS, GCA
Bitemporal hemianopia: pituitary adenoma, internal carotid aneurysm
Homonymous hemianopia: anything behind chiasm - stroke / tumour / abscess
III - Oculomotor
Partial (pupil spared) - diabetes
Complete: PCA aneurysm, raised ICP with tentorial herniation
Features: eye deviated ‘down and out’, ptosis, dilated pupil if complete
IV - trochlear
Single palsy rare
Usually due to orbit trauma
V - Trigeminal
Idiopathic (trigeminal neuralgia)
Acoustic neuroma
Herpes zoster
VI - Abducens
Skull # involving temporal bone
Nasopharyngeal carcinoma
Raised ICP (false localising sign)
VII - Facial
LMN (forehead affected) - Bell’s palsy, malignant parotid tumour, Herpes Zoster, sarcoid (often bilateral)
UMN (forehead spared) - stroke / tumour
VIII - Vestibulocochlear
Excessive noise levels
Meniere’s disease
Furosemide
Aminoglycoside antibiotics (gentamicin)
IX / X / XII - Bulbar
LMN (bulbar palsy) - MND, diptheria, polio, myasthenia gravis, GBS
UMN (pseudobulbar palsy) - MND, bilateral strokes, MS
Causes of any CN palsy
Diabetes Stroke Tumour MS Sarcoid SLE Vasculitis
Ptosis
Unilateral: CN III palsy, Horner’s syndrome, congenital
Bilateral: myasthenia gravis, myotonic dystrophy, congenital
Ophthalmoplegia
Myasthenia gravis Cranial nerve palsy Graves' disease Wernicke's encephalopathy Progressive supranuclear palsy (vertigal gaze)
Internuclear ophthalmoplegia
Disorder of conjugate lateral gaze caused by a lesion in the medial longitudinal fasciculus
Causes failure of ADduction of eye on affected side
In a left-sided INO: lateral gaze to left is normal, on attempting to look to the right the right eye ABducts normally, left eye fails to ADduct and remains looking straight ahead, right eye consequently displays nystagmus as it attempts to compensate
Causes of Internuclear Ophthalmoplegia
MS
Stroke
Lyme disease (rare)
TCA in overdose (rare)
