[Auditory brain stem potentials evoked by electrical stimulation of cochlear nuclei during central auditive implant setting].

INTRODUCTION

The implantation of a stimulator over the surface of the cochlear nuclei can provide a partial auditive capability to patients deaf due to a bilateral lesion of the 8th nerve. Intraoperative monitoring of short latency electrically-evoked potentials is useful to asses the correct positioning of the implant, specially when there are anatomical distortions.

PATIENTS AND METHODS

Evoked potentials from two patients with type II neurofibromatosis were recorded during implantation surgery, using a blanker system to eliminate the stimulus artifact.

RESULTS

In both cases, two-peak vertex-positive responses were obtained, with latencies between 0.4-0.5 and 1.2-1.4, respectively. This responses are similar to the most frequent response described.

DISCUSSION

Intraoperative monitoring of electrically-evoked auditory brainstem responses is a useful technique to confirm the correct positioning of the cochlear stimulator. The study of the morphology of these responses can help to understand the mechanisms involved in the generation by the brainstem of the auditive evoked potentials. More experience on this subject is needed to establish a correlation between intraoperative results and postoperative stimulator function.