Figure 1. Surgery of implantation of ABR and DBS electrodes.

(A) After exposing the skull, the vertex electrode is attached with a screw in the skull and the mastoid electrode is subcutaneously tunneled to the mastoid and also fixated with a screw. Three boreholes are made for anchoring screws to later fixate the structure with dental cement. (B) Boreholes for the DBS electrodes are drilled at coordinates calculated from the bregma level. Calculation of the boreholes and placement of the DBS electrodes are performed within a stereotactic frame. (C) All electrodes are in place and the construct is fixated with dental cement. ABR, auditory brainstem response; DBS, deep brain stimulation.