Internuclear Ophthalmoplegia & Nystagmus

Key points

• INO: failure of adduction on lateral gaze with nystagmus of the abducting eye — medial longitudinal fasciculus lesion; convergence preserved.
• Bilateral INO in a young patient → multiple sclerosis; unilateral in elderly → stroke.
• Nystagmus: jerk (vestibular/cerebellar) vs pendular (congenital/visual).
• Upbeat nystagmus — brainstem (Wernicke's); downbeat — foramen magnum lesions.

Decision points in this pathway

• Bilateral INO in young patient?

The full step-by-step algorithm, including what to do at each branch, opens in the app for approved members.