Exploratory tympanotomy: an integral part of cochlear implantation

We report on 113 multichannel intracochlear implantations. Although the surgical approach has evolved as a result of new implant designs, one essential step has remained, namely initial exploratory tympanotomy. This 15-min procedure allows direct anatomical assessment and work in the middle ear. After direct exposure, the lip of the niche is removed and the round window membrane is visualized. The basal turn of the cochlea is then assessed for patency, and the capability of inserting electrodes is verified. The surgical procedure is then performed in the knowledge that an adequate insertion will be possible. This approach allows insertion through the round window instead of a cochleostomy hole, thus avoiding potential damage to remaining neural structures and additional exposure of inner ear structures and electrodes to potential middle ear infections. It also requires a limited mastoidectomy (extended antrotomy) as the facial recess is visualized from the middle ear side (avoiding the need for extensive drilling), and the mastoid and facial recess openings are only used as conduits for the electrode array. In this study, 14/113 patients (12.4%) had either different degrees of ossification (n = 11) or Mondini deformity (n = 3). Direct work in the middle ear allowed handling and drilling as required in all cases. In two cases with severe ossification, a cochlea was sculpted around the modiolus. This included drilling of the anterior portion, which is inaccessible using the facial recess approach.