Positioning downbeat nystagmus in an uvular lesion

The pathomechanism of positioning downbeat nystagmus (pDBN) is not yet known. In contrast to central positional downbeat nystagmus pDBN requires rapid head positioning manouvres to be elicited. We examined a 43-year old patient who suffered from head positioning vertigo (HPV) in the head hanging position following a circumscribed, partial vermal (uvular) resection of a dysembroplastic neuroepithelial tumor. Neurological examination revealed impaired downward smooth pursuit eye movements. Rapid head positioning manouvres in the head hanging position elicited a typical DBN which increased within a few seconds and…