Prospective Study of Round Window Versus Cochleostomy Approach to CI Surgery

In 1985, the United States Food and Drug Administration (FDA) approved multichannel cochlear
implants (CIs) for adults with profound hearing loss; and in 1990, implantation was approved
for children. Since then, this procedure has become the standard of care for patients with
severe-to-profound sensorineural hearing loss. Successful outcomes are dependent not only on
extrinsic factors, but also on intrinsic factors that cannot always be modified by the CI
team. 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.

Earlier studies have found that, because of its dimensions and proximity to the spiral
ganglion cells, the scala tympani (ST) is the preferred location for CI electrode placement.
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.