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Central
Right internuclear ophthalmoplegia (right INO)
Right medial longitudinal fasciculus (MLF)
Live animation
Fast-phase: → right-beating horizontal · [DISSOCIATED — eyes differ]
Position-over-time tracing
Live strip-chart. Horizontal, vertical, and torsional channels. (Trace shown is for left eye — eyes are dissociated.)
In a sentence
On leftward gaze: adduction of the RIGHT eye is slowed/incomplete, with abducting (dissociated) nystagmus of the LEFT eye.
Clinical pearls
- ◆INO is named for the side of the LESION = side of the impaired ADducting eye.
- ◆MS is the leading cause in young patients; brainstem stroke in older patients.
- ◆Bilateral INO ('WEBINO' if walleyed) almost always = MS.
- ◆Convergence may be preserved if lesion is below the third-nerve nucleus.
- ◆Vertical gaze-evoked nystagmus may coexist.
Common associations
- MS (young, bilateral)
- Pontine stroke (older, unilateral)
- Brainstem glioma
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