PERSISTENT DIRECTION-CHANGING POSITIONAL NYSTAGMUS - ANOTHER VARIANT OF BENIGN POSITIONAL NYSTAGMUS

Positional nystagmus that does not fatigue, persists as long as the position is held, and changes direction in different head positions has typically been attributed to central vestibular lesions. We recently studied three patients who presented with positional nystagmus having these features but almost certainly of benign peripheral origin. All three had an initial history typical of benign positional vertigo and, in two, the persistent direction-changing positional nystagmus occurred after the patient underwent a maneuver to remove debris from the posterior semicircular canal. The positional nystagmus profile and clinical course are consistent with the debris leaving the posterior semicircular canal and becoming attached to the cupula of the horizontal semicircular canal.