6TH Nerve Palsy

Question 1

Aetiology over 50

Answer 1

• most common is microvascular
• due to diabetes, hypertension and cholesterol
• giant cell arteritis
• stroke
• trauma

Question 2

Aetiology under 50

Answer 2

• multiple sclerosis
• increased intra cranial pressure
• severe ear infection
• cavernous sinus mass
• tumour
• trauma
• viral infection
• pituitary gland tumor
• pappilledema and 6th palsy = tumour

Question 3

Aetiology in children

Answer 3

• hydrocephalus
• congenital VI
• tumours most common
• trauma
• viral infection
• idiopathic

Question 4

6th N palsy features

Answer 4

• esotropia in primary position, greater in distance
• limited abduction of affected eye
• Px complains of uncrossed diplopia
• possible face turn to unaffected side
• field of BSV moved toward unaffected side

Question 5

Differential diagnosis

Answer 5

• myasthenia gravis
• Duane’s
• infantile esotropia
• mobeius syndrome
• medial wall fracture

Question 6

Investigations

Answer 6

• cover test
• lateral versions measurement
• saccades show hypomeropia of affected side
• smooth pursuits show limited abduction of affected eye
• lees screen
• smaller VF
• contralateral eye overacts

Question 7

Management of 6th nerve palsy

Answer 7

• prisms to join diplopia
• large diplopia - occlude one eye
• allow 6 months for recovery
• if only partial recovery, Botox surgery can be used to resign BSV in primary position