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OcularMovements
Question | Answer |
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Periodic alternating nystagmus | When looking straight ahead eyes beat to one side for a few seconds to a minute, slow and stop beating, then begin to beat to the opposite side. This alternates every 2 minutes. Indicates lesion of the flocculonodular lobe of the cerebellum. |
Upbeating nystagmus | Jerk nystagmus evoked by upgaze. Seen in a variety of brainstem and cerebellar lesions, so localizes to the posterior fossa. |
Downbeat nystagmus | Jerk nystagmus evoked by down gaze or seen in the primary position. Suggests lesion of the cervicomedullary junction, commonly seen in Arnold-Chiari malformations. |
Pendular nystagmus | Non-jerk nystagmus with a side-to-side or up-and-down motion with equal excursions back and forth. Seen in a variety of conditions: typical of congenital nystagmus (horizontal pendular nystagmus). |
Elliptical nystagmus | Combination of pendular nystagmus in both horizontal and vertical directions that are out of phase causing a rotatory movement that can be circular or elliptical. Brainstem conditions cause this, and it may be seen commonly in multiple sclerosis. |
Internuclear opthalmoparesis | When looking straight ahead, the eyes are OK. Looking away from side affected, the adducting eye either does not adduct or lags behind the abducting eye, and the abducting eye has a gaze-evoked jerk nystagmus. MLF in the pons or midbrain lesion. |
Opsoclonus | Sudden large amplitude conjugate eye movements in various directions. May be due to cerebellar disease. May be seen in some paraneoplastic conditions, occasionally associated with myoclonus (opsoclonus-myoclonus syndrome). |
Ocular flutter | In primary position eyes suddenly have a rapid, jiggling motion in the horizontal plane lasting a second, occurring intermittently. Brainstem lesions. |
Rebound nystagmus | On gazing in one direction eyes have a gaze-evoked nystagmus to that side that gradually reduces. On return to primary position eyes rebound to beat in the opposite direction. Cerebellar lesions. |