Prospective Study of Round Window Versus Cochleostomy Approach to CI Surgery

Prospective Randomized Controlled Double-blinded Study Comparing Cochlear Implantation Through a Round Window Versus Cochleostomy Approach

To the investigators' knowledge, no clinical study has prospectively investigated the relationship between surgical insertion technique, intracochlear electrode location, and postoperative hearing outcomes. To this end, the investigators are conducting a multicenter prospective randomized controlled double-blinded study comparing round window and cochleostomy cochlear implant electrode insertion.

Cochlear implant procedure has become the standard of care for patients with severe-to-profound sensorineural hearing loss. Successful outcomes are dependent on extrinsic and intrinsic factors. Significant predictive factors for hearing outcomes in patients with CIs have been previously reported. These include, but are not limited to, duration of deafness, level of preimplant speech recognition, pre/postlingual status, and the coupling of device electrodes. Recipient age does not appear to have a significant impact on hearing outcomes in elderly candidates.

A number of recent studies have proposed that intraoperative factors may be important determinants of electrode location and possibly of audiological outcome. Preliminary reports suggest that intracochlear electrode position- specifically, placement within the ST-is associated with improved audiological outcomes. Additionally, different surgical techniques have been proposed to minimize trauma during electrode insertion and to increase the likelihood of placement within the ST - namely round window and anteroinferior cochleostomy electrode insertion.

Currently, the best surgical approach for electrode insertion is highly debated, fueled by a lack of strong evidence to support one method over another. While a number of CI centers have begun to utilize a round window approach, many large volume centers in the United States and world wide continue to routinely employ cochleostomy electrode insertions. With an increasing number of patients being implanted with greater degrees of residual hearing, such data will become critical towards reducing intracochlear injury and optimizing patient outcomes. To the investigators' knowledge, no clinical study has prospectively investigated the relationship between surgical insertion technique, intracochlear electrode location, and postoperative hearing outcomes. To this end, the investigators are initiating a multicenter prospective randomized controlled double-blinded study comparing round window and cochleostomy cochlear implant electrode insertion.

Inclusion criteria are:

• 18 years of age or older,
• less than a 10-year duration of deafness in the ear to be implanted,
• primary surgery,
• normal shaped cochleae,
• no retrocochlear pathology, and
• grossly normal cognitive function.

Exclusion criteria are:

• less than 18 years of age,
• prelingual deafness, or
• greater than 10-years duration of deafness in the ear to be implanted;
• prior otologic surgery in the implanted ear (excluding tympanostomy tube placement),
• inner ear malformation present in the ear to be implanted,
• retrocochlear pathology present in the auditory system to be implanted,
• developmental delay or known cognitive impairment, or
• pregnancy.