Pupil abnormalities, CN VII palsy and ptosis Flashcards
Innervation of iris sphincter (miosis)?
Parasympathetic from CN III
retina, pretectal N, EWN, CN III, ciliary ganglion, muscle
Innervation of dilater pupillae (mydriasis)?
Sympathetic from posterior hypothalamus
Causes of abnormally large pupil:
Tonic pupil
CN III palsy
Iris rubeosis
What is tonic pupil?
Delayed mydriasis with reversal of the near response
e.g. autonomic neuropathy
Causes of abnormally small pupil:
Horner’s syndrome (ptosis, miosis, anhidrosis)
Uveitis/posterior synechiae (iris adheres to lens)
Causes of CN VII palsy:
Herpes zoster Middle ear disease Mastoiditis Sarcoid and meningeal disease Tumours in parotid or skull base or brainstem Trauma
Features of CN VII palsy:
Paralysis of facial muscles Widened palpebral aperture Impaired eyelid closure Drooping of angle of mouth Can be referred for corneal exposure, watering, cosmetics
Examinations with CN VII palsy:
CNs (esp V and VI)
Middle ear exam (otoscopy)
Which nerve innervates levator palpebrae?
CN III
Differentials of ptosis:
Enopthalmos (sulcal change not lid)
Dermatochalasis (excess upper eyelid skin)
Contralateral eyelid retraction
Contralateral proptosis (e.g. thyroid eye disease)
What else will be present if the ptosis is caused by CN III palsy?
Divergent squint and dilated, unreactive pupil
Characteristics of ptosis due to myasthenia gravis?
Variable
Worse with effort
Worse at the end of the day
What else will be present if the ptosis is caused by Horner’s syndrome?
Small pupil (miosis)
Loss of ability to sweat on that side of the face
Ptosis
Congenital causes of ptosis:
Levator dystrophy
Horner’s syndrome
Mitochondrial cause of ptosis:
Chronic progressive external ophthalmoplegia (CPEO)
