A case study of high-velocity, persistent geotropic nystagmus: Is this bppv?

Background and Purpose: Deciphering the cause for a persistent, direction-changing geotropic nystagmus can be difficult. Migraine and light cupula are two possible causes, though can be confused with benign paroxysmal positional vertigo (BPPV) affecting the horizontal semicircular canal. Inmigraine, the persistent geotropic nystagmus tends to be slow; in light cupula, the nystagmus has been illustrated to beat in the direction opposite that of prone positioning. Case Description: Here we describe a patient with initial occurrence then recurrence of a high velocity (≥30 deg/sec), persistent directionchanging geotropic nystagmus and vertigo with an intensity variable based on head position, which was difficult to manage. This patient did not have migraine. The case presented uniquely as it was unlikely due to canalithiasis of the horizontal semicircular canal yet the presentation was not clearly related to the light cupula phenomena either. Intervention: In this case, the physical therapist attempted to use the barbeque roll canalith repositioning maneuver (CRM) even though the direction-changing geotropic nystagmus was persistent. The nystagmus did not resolve during the clinic visit. Outcomes and Discussion: The persistent, high velocity geotropic nystagmus resolved within 1week, however, this resolutionwas likely spontaneous and not due to the CRM intervention. Our case suggests that physical therapists assessing persistent geotropic nystagmus should wait long enough for the nystagmus to stop (∼2minutes), test for fatigue by repeating the positional nystagmus tests, incorporate a head flexion component as part of the positional testing, and attempt to identify a null point.