title: Periodic alternating skew deviation.
abstract: A 78-year-old hypertensive woman suddenly developed blurred vision, followed shortly by dizziness, difficulty walking with a tendency to veer to the left, and vertical diplopia. Examination 3 weeks later revealed a unique neuro-ophthalmologic motility pattern, which may be described as periodic alternating skew deviation. This previously unreported motility disturbance was associated with downbeat nystagmus in our patient, and a focal lesion at the level of the interstitial nucleus of Cajal was demonstrated on computed tomography. The spectrum of physiologically related motility patterns--including periodic alternating nystagmus, cyclic oculomotor paralysis, see-saw nystagmus, periodic alternating gaze deviation, "ping-pong" gaze, and intermittent aperiodic alternating skew deviation--has been considered and is helpful in topical neuro-ophthalmologic diagnosis.
mesh_terms: D000368:Aged; D001927:Brain Diseases / Q000150:complications* / Q000175:diagnosis / Q000000981:diagnostic imaging; D001933:Brain Stem; D004172:Diplopia / Q000150:complications*; D004244:Dizziness / Q000150:complications; D005158:Facial Paralysis / Q000150:complications; D005260:Female; D006801:Humans; D009069:Movement Disorders / Q000150:complications*; D009759:Nystagmus, Pathologic / Q000150:complications*; D009886:Ophthalmoplegia / Q000150:complications*; D014057:Tomography, X-Ray Computed