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Internuclear Ophthalmoplegia
Aka: Internuclear Ophthalmoplegia, Lhermitte's Syndrome, Medial Longitudinal Fasciculus Syndrome, Conjugate Gaze Palsy
- See Also
- Conjugate Gaze
- Eye Examination
- Eye Neurologic Exam
- Neurologic Anatomy of the Eye
- Extraocular Movement
- Oculocephalic Reflex
- Nystagmus
- Eye Deviation
- Pathophysiology
- Medial Longitudinal Fasciculus (MLF) - normal function
- On lateral gaze, Cranial Nerve 6 abducts the ipsilateral eye
- To maintain Conjugate Gaze, a signal is passed via MLF to the contralateral eye's CN 3 to adduct (medially) in parallel
- With a MLF lesion, the adducting eye via CN 3 fails to adduct
- In response, the abducting eye (via CN 6) demonstrates Nystagmus and Conjugate Gaze Palsy
- Extraocular Movement is normal in other directions
- Primary gaze remains parallel
- Eye convergence on near Vision remains intact
- Causes
- Older adults (esp. unilateral involvement)
- Vascular disease affecting the vertebrobasilar circulation
- Young adults (esp. bilateral involvement)
- Multiple Sclerosis
- Children
- Pontine glioma (MRI)
- Vasculitis may also cause Internuclear Ophthalmoplegia in this age group
- Alcoholism
- Wernicke's Encephalopathy
- References
- Berson (1990) Ophthalmology Study Guide, AAO, p. 116-7