He added that while the procedure can be beneficial to certain patients, and can even be economical due to the savings on operating-room costs and a faster return to patient functionality, more studies on outcomes would be useful, and vigilance about abuse is needed.
Explore this issue:April 2015
Bilateral Cochlear Implants: When Are They Indicated?
Doug Backous, MD, medical director of the Center for Hearing and Skull Base Surgery at Swedish Medical Center in Seattle, said all patients who meet the criteria should get a bilateral cochlear implant.
The indications for a bilateral implant are the same as those for a unilateral implant: adults with bilateral severe to profound deafness with limited benefit from appropriate acoustic hearing aids and children with bilateral severe to profound deafness (for patients aged 12 to 18 months, it should be profound) and no progress with acoustic hearing aids.
“The problem is that in the United States, depending on which study that you read, our market penetration for cochlear implants for patients who are eligible is somewhere between 9% and 18%,” said Dr. Backous, who is a member of the Cochlear Corporation surgical advisory board.
A bilateral implant allows for better sound localization, not because of the time difference in sound reaching each ear, which isn’t registered well with cochlear implants, but because of the difference in the intensity of the sound for each ear.
Bilateral implants also help reduce the “head shadow effect,” in which the head blocks sound to the ear that isn’t facing the sound; they also help with binaural summation, in which potentially difficult-to-hear sounds have improved audibility when processed through both ears, and help differentiate speech from noise because each ear is able to process the sounds, a process called the “squelch effect.”
Dr. Backous suggested that bilateral implants are not used more often because of insurance considerations. Insurance coverage normally applies if a bilateral implant is received, but if the implants are done sequentially, another justification process is required. “So why don’t we do it for everyone? It costs too much,” he said. “If we could get this approved by insurance companies in the Pacific Northwest you would have a lot more bilateral users.”
John Niparko, MD, chair of otolaryngology-head and neck surgery in the Keck School of Medicine at the University of Southern California in Los Angeles, discussed some of the limitations of bilateral implants. “Bilateral cochlear implantation makes great sense if we appreciate that, currently, comparing a bilateral situation to binaural processing is comparing apples to oranges,” he said. “They are two fundamentally very different concepts, and this impacts, I think, the way we will go forward in advising our patients and assisting them in the management of their child’s deafness.”