From vestibular implant to cortex: electrically evoked vestibular responses.

PURPOSE

Understanding central vestibular pathways remains challenging and requires innovative measurement approaches. A vestibular implant offers unique access through specific electrical stimulation of the vestibular end organ. This study explored the feasibility of using vestibular implant stimulation to obtain vestibular evoked potentials, using electroencephalography (EEG).

METHODS

A vestibular implant was used in nine participants to evoke vestibular potentials by targeting the ampullary nerves of the semicircular canals. Short latency potentials were recorded using one channel EEG on all participants. In three participants, long latency potentials were recorded with 128 channel EEG. Responses were analyzed in terms of latency, shape, and location, and tested for correlation with stimulus intensity. EEG thresholds were compared with vestibular outcome thresholds (i.e., perception and vestibulo-ocular reflexes).

RESULTS

The measurement setup proved feasible for obtaining vestibular potentials. A consistent short latency response, identified as the vestibular brainstem response, was identified in five participants and across targeted nerves. Long latency responses revealed defined and localized independent components, with amplitudes correlating with stimulus intensity. Electrically evoked response thresholds matched thresholds of patient perception and eye movement recordings.

CONCLUSIONS

Vestibular implant stimulation elicited reproducible short and long latency responses. This approach creates new opportunities for investigating vestibular processing and evaluating vestibular implant responses.