Therapy-Resistant Atypical Downbeat Nystagmus with Vertigo Confined to Specific Head-Hanging Positions: Mapping to the Gravity Vector on a Multi-Axis Turntable

Downbeat nystagmus (DBN) observed in head-hanging positions, may be of central or peripheral origin. Central DBN positions is mostly due to a disorder the vestibulo-cerebellum, whereas usually attributed canalolithiasis an anterior semicircular canal. Here, we describe atypical case patient who, after head trauma, experienced severe and stereotypic vertigo attacks being placed various positions. Vertigo lasted 10–15 s was always associated with robust DBN. The provocation transient DBN, which both showed no decrease upon repetition maneuvers, depended on yaw orientation relative trunk angle backward pitch. On motorized, multi-axis turntable, identified two-dimensional Helmholtz coordinates at occurred (<i>y</i>-axis: horizontal, space-fixed; <i>z</i>-axis: vertical, head-fixed; <i>x</i>-axis: torsional, head-fixed, unchanged). This area DBN-associated did not change when whole-body rotations took different paths (e.g., by forwarding pitch) were executed velocities. Moreover, intensity also independent rotation So far, therapeutic approaches repeated liberation maneuvers cranial vibrations successful. We speculate that this are macular damage, possibly unstable otolithic membrane that, specific orientations gravity, slips into position causing paroxysmal stimulation inhibition hair cells.