Problems with cochlear implants for deaf children are rare, with only some three percent of children who got the implants at one hospital needing new ones because of technical problems, Canadian researchers said.

Their report, in the Archives of Otolaryngology-Head & Neck Surgery, also showed that only a few of those children suffered a drop in hearing or speaking skills after the new devices – which transmit sound directly to the auditory nerve – were implanted.

"People used to say the complication rate is higher in children, the failure rate is higher in children, and we found that that was not the case," said Blake Papsin, director of the cochlear implant program at the Hospital for Sick Children in Toronto, who was senior author for the study.

While cochlear implants don't allow deaf children to hear in the same way that other children do, the devices do mean they can go to regular schools, have normal conversations and listen to music.

The study included 738 children, most born hard of hearing because of genetics. They all received a cochlear implant in at least one year between 1990 and 2010 and had the procedures when they were an average two or three years old.

During that time, the hospital treated 34 children whose implants had stopped working and who needed surgery to put in a new device.

When the researchers took out the seven children who got their original implant at another hospital, they found that just under three percent of the patients they treated with a first cochlear implant needed a second due to malfunctions over six years of using the devices.

Almost all of the children who needed a new device implanted maintained or improved their hearing and speaking abilities after the second procedure. Just two had a significant drop in those skills.

"Once these things fail, replacing them does tend to get the kids' hearing back to or close to where it was before the device failed," said Josef Shargorodsky, who studies hearing problems at Massachusetts Eye and Ear infirmary and Brigham and Women's Hospital in Boston, and wasn't involved in the new study.

He added that the number of device failures in this study was lower than in most previous reports, possibly because cochlear implant technology is improving.

But despite the low rate of failures, almost all deaf children will probably eventually need a new implant, although it's hard to know if a typical person would need just one or a few, said Papsin, who is on the speaker's bureau of the Cochlear Americas Corporation, which markets the devices.

"It's pretty clear that these devices are unlikely, even though beautifully made, to last a lifetime," he told Reuters Health.

More than 200,000 people globally have received cochlear implants, including about 70,000 in the United States.