Innovation in Cochlear Impant Surgery

Twenty years ago, the use of bilateral implants would have headlined any conference on innovations in cochlear implantation. Today, the procedure has become routine for children and adults. Here’s a look at procedures that now represent the cutting edge of cochlear implant (CI) surgery.

Hybrid Devices

There are several candidates for top billing, but one of the more exciting advances involves hybrid implants and techniques that preserve residual hearing, according to Bruce Gantz, MD, professor and head of the department of otolaryngology-head and neck surgery at the University of Iowa Hospitals and Clinics in Iowa City.

“It isn’t all that long ago that implanting a cochlea of a patient with residual hearing would have been unthinkable,” said Dr. Gantz. That’s the case, he noted, because standard-length cochlear implant electrodes that extend more than 20 mm into the scala tympani can obliterate key structures and almost wipe out residual hearing (Acta Otolaryngol. 2004;124:272-280). Although “soft surgery” techniques with the standard-length electrode implants can prevent some of that damage (Otol Neurotol. 2006;27:1083-1088), Dr. Gantz noted, shorter-length hybrid devices offer a dual benefit: They preserve residual hearing in adults and children, while also sparing cells in the organ of Corti, which preliminary studies have shown may respond to future advances in molecular or genetic treatments of the inner ear (Nature. 2006;441:984-987).

“Preserving residual hearing—regardless of variations in technique—is here to stay.”

—Craig A. Buchman, MD

“I realize the latter benefit is somewhat theoretical,” Dr. Gantz said. “And it’s most relevant to younger patients who have decades of life ahead, where they can eventually benefit from these advances. But our studies also have shown that significant clinical benefits are accruing now—in both young and older patients—who we’ve implanted with the hybrid device.”

A more recent study by Dr. Gantz and colleagues in profoundly deaf children (Otol Neurotol. 2010;31(8):1300-1309) evaluated another short-electrode (10 mm) device, the Nucleus Hybrid S12, which employs 10 active stimulating electrodes versus the six in the Hybrid S device used in the multicenter FDA trial. In the newer study, patients were implanted with the Nucleus S12 in one ear and a standard-length cochlear implant in the other ear. The results showed that both implants provide similar speech perception scores when tested separately, Dr. Gantz noted. “These results suggest that the brain can accommodate for a shorter, less damaging electrode with only 10 electrodes implanted into the base of the cochlea,” he said.