New Technology Expands Applications for Cochlear Implants
Technology breakthroughs in cochlear implants are allowing doctors to help more patients with residual hearing than ever before, a vast improvement over the early days of implants, according to George Alexiades, MD, an otologist/neurotologist and Director of the Cochlear Implant Center at NewYork-Presbyterian/Weill Cornell Medical Center. “When we first began performing cochlear implants we would tell our patients that their residual hearing would be gone after surgery,” he says. “However, over time we have refined surgical techniques and the implants have become more delicate and advanced. Today, we are much more consistent in preserving residual hearing even with patients who have very little. We try to save as much of their residual low-frequency acoustic hearing as possible so that they still have some sound awareness when they take their cochlear implants off.”
Extending Criteria for Cochlear Implants
The cochlear implant has seen marked improvements in its more than 35-year history. In recent years, Dr. Alexiades and his colleagues at the Cochlear Implant Center have expanded their patient selection criteria and widened their pool of potential implant candidates. “Cochlear implants initially were relegated to patients with severe-to-profound sensorineural hearing loss in both ears who were not getting enough benefit from traditional hearing aids,” says Dr. Alexiades.
In recent years, FDA guidelines have broadened to include anyone with moderate-to-profound hearing loss in both ears who are not getting sufficient benefit with a traditional hearing aid. “The big change more recently is that we have been inching towards including more people with residual hearing loss because we’ve seen the benefit of implants outweighing traditional hearing aids,” says Dr. Alexiades. “We are now offering implants to people with unilateral hearing loss and children younger than one year of age.”
Electro-acoustic stimulation, or hybrid devices, received FDA approval two years ago. This can be the solution for those who hear too well to receive a conventional cochlear implant, but who cannot use a traditional hearing aid. The combination of acoustic hearing for the low frequencies and electric stimulation for the mid-to-high frequencies has been life-changing for patients, notes Dr. Alexiades. With bimodal fitting, in contrast to the hybrid situation, one ear is stimulated acoustically with a hearing aid and the opposite ear is stimulated electrically with a cochlear implant to supply the mid-to-high frequency sounds.
“We have found that patients with hybrid devices do significantly better than patients with a hearing aid alone, and better than patients with a full cochlear implant,” says Dr. Alexiades. “Again, this approach is for patients who could have normal hearing in low frequencies but by the middle frequencies – usually 1000 Hz and above – their hearing is in the severe-to-profound range. They just don’t get enough information with their hearing aids to function very well. The cochlear implant helps give them high frequency information and the hearing aid helps give them the low frequencies.”
“Outcomes have been very good,” continues Dr. Alexiades, who has performed some 20 hybrid cochlear implants at the Center. “The advantage of combining a hearing aid and a cochlear implant is that patients tend to hear better with background noise and in music appreciation than individuals who have just a cochlear implant with no acoustic component.”
Dr. Alexiades and his Weill Cornell colleagues recently took part in a multicenter clinical trial to test an electric-acoustic stimulation system for adults with residual low-frequency hearing and severe-to-profound hearing loss in the mid-to-high frequencies. The study, the results of which were published in Otology & Neurotology in March 2018, focused on 67 of 73 patients who completed outcome measures for all study intervals. Speech perception was assessed using City University of New York sentences in noise and consonant-nucleus-consonant words in quiet.
Of the 67 patients, 79 percent experienced less than a 30 dB HL low-frequency pure-tone average (250-1000 Hz) shift, and 97 percent were able to use the acoustic unit at 12 months post-activation; 94 percent of patients performed similarly to or better than their preoperative performance on City University of New York sentences in noise at 12 months post-activation, with 85 percent demonstrating improvement; and 97 percent of subjects performed similarly or better on consonant-nucleus-consonant words in quiet, with 84 percent demonstrating improvement.
Addressing Unilateral Hearing Loss
The loss of hearing in one ear — unilateral hearing loss or single-sided deafness — is more common and more bothersome than many people realize. In these patients, one ear has normal or near normal hearing, while the other has profound-to-severe hearing loss. The symptoms of unilateral hearing loss vary. In addition to impaired hearing on one side, some people may have difficulty determining the direction of sounds making it dangerous to cross a street or navigate in traffic. Others may be unable to hear sounds from a particular direction, with the most common symptom being an inability to separate background noise from sounds the individual wants to hear.
“Previously, we could only offer these patients special types of hearing aids that could shunt the signal from one side to the other but never really restored hearing in the ear that had lost hearing,” says Dr. Alexiades. “With only one ear you can’t localize sound. In certain circumstances, however, patients with unilateral hearing loss will do very well with a cochlear implant. We can implant the one ear that has severe-to-profound hearing loss and over time the patient is able to fuse the signal coming in from the cochlear implant with the normal ear. Using both together, they can actually have restored hearing in the ear that had lost hearing. However, this approach only works well in someone who has recently lost hearing on one side; it can’t be many years later.”
While the average age of Dr. Alexiades’ patient population varies, the majority fall at either end of the spectrum – the elderly or the very young. “Many of our patients are either children under two years old or older adults, but there is still a great number of patients with hearing loss in their 40s and 50s,” he says. “Some patients have their original device implanted in the 1980s, but in all likelihood, most people, especially young patients, will have to have at least one revision in their lifetime.”
Among children, studies have shown that outcomes are more successful with early intervention, and Dr. Alexiades believes that the nationwide universal screening policy at birth is crucial to help identify children with hearing loss.
“Patient selection is an evolving process,” adds Dr. Alexiades. “Patients who were not deemed a cochlear implant candidate five years ago may very well be an implant candidate today.”
Pillsbury HC 3rd, Dillon MT, Buchman CA, Staecker H, Prentiss SM, Ruckenstein MJ, Bigelow DC, Telischi FF, Martinez DM, Runge CL, Friedland DR, Blevins NH, Larky JB, Alexiades G, et al. Multicenter U.S. clinical trial with an electric-acoustic stimulation (EAS) system in adults: Final outcomes. Otology & Neurotology. 2018 Mar;39(3):299-305.
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