Pupil Abnormalities, Facial Nerve Palsy, Ptosis

Question 1

Pupil anatomy

• what reaction is normal
• what is not

What controls pupillary innervation?

Answer 1

U0.5mm - physiological, same at all light levels.

Pathological - varies between light and dark

Sphincter pupillae - PNS 3rd CN => constriction
-4 neurone reflex arc with ACh (retina => pretectal => EWN => ciliary ganglion via CN3 => ciliary nerves to sphincter muscles)

Dilator pupillae - SNS => dilation
-3 neurone arc (hypothalamus => C8-T2 => sup cervical ganglion => hitchikes along ICA to dilator muscles

Question 2

How do the pupils normally react on examination

Pupil responses

Answer 2

Dark room => dilate
-any constriction is abnormal

Bright room => constrict
-any dilation is abnormal

Ask patient to focus on distant target
Direct response => same eye constricts
Consensual => other eye constricts

Ask patient to focus on distant target and then a near target
Near response => dilation to constriction

RADP => when light shone in affected eye, both eyes appear to dilate

Question 3

Anisocoria

• what is it
• causes of abnormally large pupils
• causes of abnormally small pupils

Answer 3

Unequal pupil size

Large
Tonic pupil - constricts slowly in bright light, constriction is faster in accommodation
-3rd nerve palsy
-dilating eye drops
-trauma
Neovascularisation of iris
Physiological

Small
Horners syndrome
-pilocarpine eye drops
Uveitis
Physiological

Question 4

Facial nerve palsy

• causes
• presentation
• examination findings
• management

Answer 4

Causes - MAINLY IDIOPATHIC

• brainstem, skull base disease
• peripheral disease - HZ, OM, mastoiditis, parotid tumours
• sarcoid
• trauma, surgery

Presentation

• facial muscle paralysis
• inability to close eye
• drooping mouth angle

Examination
-cranial nerves FOCUS ON 567 and middle ear

Management

• ENT referral
• neuroimaging if neurological features or persists after 3 months
• opthalmology referral if eye involvement

Question 5

Ptosis

• presentation
• patient assessment
• differentials

Answer 5

CN3 - levator palpebrae

Drooping eyelid
Visual field reduced if pupils obscured
-risk of lazy eye in children

False impressions of ptosis

• enopthalmos - post displacement of eye
• dermatochalasis - excess upper eyelid skin
• contralateral eyelid retraction
• contralateral proptosis - forward protrusion of eye

Question 6

Ptosis causes

• congenital
• acquired

Answer 6

Congenital
-levator dystrophy

Idiopathic
-age

Pathological

• Horners
• MG
• 3rd nerve palsy
• Trauma
• Eyelid tumour => mechanical ptosis