Diplopia and Oculomotor Palsies

Question 1

Single most common isolated oculomotor palsy

Answer 1

Sixth nerve palsy

This is because it can be produced both by ischemia and by simple nerve compression in the setting if elevated ICP!

Question 2

Most common cause of a sixth nerve palsy

Answer 2

Vascular

Don’t let the association with ICP fool you, the most common isolated 6th nerve palsy is still vascular! But mass lesion should be on your radar.

Question 3

6th nerve palsy and aneurysms

Answer 3

PICA aneurysms and basilar artery aneurysms can both compress the nerve

Question 4

Where is the 6th nerve impinged in elevated ICP?

Answer 4

The petrous temporal ridge

Question 5

Binocular vs monocular diplopia

Answer 5

Binocular: An oculomotor misalignment problem. Resolved by covering one eye.

Monocular: Either a diffraction problem (lens, aqueous humor, vitreous humor) OR an occipital lobe problem (neurodegenerative disease, seizure)

Question 6

Common causes of oculomotor deficits

Answer 6

• Vascular
  
  • Pressure, A1c
• Rheumatologic
  
  • ANA, ESR, CRP
• Infectious
  
  • CBC

Question 7

Treatment of an occulomotor palsy

Answer 7

• Correction of underlying risk factors
• Obsereve empirically for 1-3 months for improvement
  
  • Patching of involved eye may alleviate symptoms
  • Eyeglasses made with prism lens may minimize or correct diplopia during recovery
• Interventions:
  
  • Injection of botox into antagonist muscle (lasts 3-6 months)
  • Strabismus surgery on the extraocular muscle may be necessary in non-resolving cases

Question 8

Monocular diplopia is usually ___-trinsic while binocular diplopia is usually ___-trinsic

Answer 8

Monocular diplopia is usually IN-trinsic while binocular diplopia is usually EX-trinsic