Deaf children who already had one cochlear implant had improvements in speech, hearing and related quality of life measures after a second was implanted in the other ear, researchers from the Netherlands reported this week.
And the degree of improvement didn't depend on how old kids were when they got their second implant, according to the study, published in the Archives of Otolaryngology--Head & Neck Surgery.
An improved quality of life after a second implant "is not surprising," said Betty Loy, who studies deafness and cochlear implants at the University of Texas Southwestern Medical Center in Dallas.
"I definitely would expect that to improve over time as the brain adjusts to that second implant. You're going to get better and better and better at doing all the things that bilateral hearing allows you to do," added Loy, who was not involved in the new study.
Cochlear implants transmit sound directly to the auditory nerve. Getting an implant requires surgery on the ear, and costs of the procedure and follow-up care can exceed $50,000. There's also the possibility of complications from infection or damage to the device -- but those are relatively rare.
Because of the costs and risks, Loy said that doctors were initially hesitant to give young kids cochlear implants in both ears. But over time, she added, that trend has changed in the United States, and studies have shown that deaf children with two implants do better on hearing tests than those with a single implant.
Recently, Canadian researchers also provided reassuring news on cochlear implants, reporting that only a small fraction of children they operated on in the last 20 years had technical problems with their cochlear implants and needed new ones (see Reuters Health story of December 21, 2011.)
For the current study, researchers tracked 30 children who already had one cochlear implant and were getting a second one put in at the Radboud University Nijmegen Medical Centre.
Marloes Sparreboom and colleagues gave parents general and hearing-specific questionnaires related to their kids' quality of life before the second implant was put in, and one and two years after implantation. On average, kids were five years old when they had their second procedure.
On general health and quality of life questionnaires, there was no change in kids' scores after the second implant. Those scores were generally within the healthy range for hearing kids anyway, according to the researchers.
But on questionnaires that specifically asked how well the children were able to listen to speech in a noisy environment, and other quality of life measures related to hearing and speaking, kids improved both one and two years after getting their second implant.
For example, on the Speech, Spatial, and Qualities of Hearing Scale, scored here from 0 to 1, children had an average score of 0.48 before getting their second implant, 0.60 a year after getting it and 0.62 after two years.
Children in the study were as old as eight and a half when they got their second implant, and age didn't seem to factor into their improvement after the procedure.
A comparison group of kids who still had a single cochlear implant didn't improve on hearing-related quality of life measures over a one-year period.
"The results imply that the second implant causes the effect on the hearing-specific (quality of life) and not simply maturation," Sparreboom told Reuters Health in an email.
Sparreboom said the findings show that having implants in both ears can be beneficial for listening as measured by doctors and in daily life.
"Classrooms are noisy even for typical-hearing children," said Loy. "Teachers turn away when they're writing on the blackboard, you can't read their lips. The situations that hearing-impaired children find themselves in are difficult even under the best circumstances."
With multiple implants, Loy added, "You're going to learn how to localize sound better, you're going to learn how to focus better on the speech in noise...and you get better at that over time. If you can hear, and you know what's going on, your quality of life is better."