Apogeotropic and Downbeat Central Positional Nystagmus Provoked While Seated

This is a young man with intermittent complaints of positional vertigo. With Dix-Hallpike and roll testing, he had apogeotropic positional nystagmus (e.g., right beating nystagmus with the left ear down, and left beating nystagmus with the right ear down) in addition to strong downbeat nystagmus induced by prone positioning. Work-up for cerebellar disorders, especially those affecting the nodulus and uvula, was unrevealing including high resolution thin cuts through the posterior fossa, as well as normal labs and cerebrospinal fluid looking for a variety of paraneoplastic, infectious, inflammatory, and autoimmune disorders. Unfortunately, symptoms persisted over the span of 1 year, although fortunately, the symptoms and signs of positional nystagmus were quite stable with some symptomatic improvement. Positional nystagmus was seen with and without fixation. With fixation in an upright position, there was no spontaneous nystagmus, no gaze evoked nystagmus, and smooth pursuit and VOR suppression were normal. There was no gait ataxia, or any general neurologic abnormalities. In this video, the patient is asked, while sitting in the chair, to simply tilt his head 45 degrees to the right and to the left, and his apogeotropic positional nystagmus can be appreciated. There was only mild dizziness provoked by these head movements. This pattern of nystagmus had been constant for well over a year despite repeated repositioning maneuvers for possible horizontal canal BPPV, and there was no pseudo-spontaneous horizontal nystagmus or reversal of horizontal nystagmus during bow and lean; therefore, a refractory variant of apogeotropic horizontal canal benign paroxysmal positional vertigo seemed unlikely. Additionally, there is upbeat nystagmus and a lean position (chin up), as well as downbeat nystagmus in a bow position (chin down, the same pattern of downbeat nystagmus as can be demonstrated with prone positioning). Taken together, the combination of positional vertical nystagmus (that is not compatible with posterior canal or anterior canal benign paroxysmal positional vertigo) with apogeotropic nystagmus is highly suggestive of central positional nystagmus. This video demonstrates that the evaluation of positional nystagmus can sometimes be completed in a chair, so that even when an exam table is unavailable, the clinician can glean valuable information from simply changing the position of the head relative to gravity.