Vibrant soundbridge surgery: evaluation of transcanal surgical approaches

Since its introduction, surgery for the placement of the Vibrant Soundbridge (VSB) device has been performed using a facial recess approach. Because of the size of the VSB device, this approach requires a large facial recess that can lead to complications, i.e., facial palsy and/or taste disturbance. The purpose of this study is to develop and compare transcanal surgical approaches for leading the VSB into the middle ear.

Cadaver temporal bones in a university temporal bone laboratory.

First, two experienced senior surgeons validated the three possible approaches in human temporal bone: 1) the classical facial recess approach; 2) a small mastoidectomy, elevation of a tympanomeatal flap, small atticotomy, 0.5-mm cutting of the bony external auditory canal (EAC) from the cortical plane on its approximately two-thirds to three-fourths and then a trough to pass the electrode array into the middle ear; and 3) similar to the second approach but with replacing the cutting of the bony EAC with a tunnel from the mastoid cavity to the EAC. Both the second and third approaches were transcanal. Next, five residents and six attending surgeons performed the three operations and evaluate these different approaches by using analog visual scales (VAS) for each procedure. They assess the following: 1) the ease of passing the electrode array and the Floating Mass Transducer (FMT) into the middle ear, 2) the ease for FMT clipping, and 3) their self-confidence using each approach. Time required for the three operations was measured. Measurements of landmarks were obtained on all temporal bones. Two patient cases illustrate the clinical application of this new surgical approach.

The two transcanal approaches were assessed to be easier, faster, and safer methods for VSB surgery than the classic facial recess approach.

VSB surgery has been performed using a facial recess approach with risk for facial nerve and taste disturbance. Transcanal approaches are good alternative for this surgery. Three major limitations are to be assessed in future patient studies: the pathologic findings of the EAC, the design of the FMT regarding the axis of the ossicular chain, the long-term evaluation of the skin of the external ear canal.