Cochlear implants can improve speech and quality of life in adults with severe hearing loss - and two implants seem to work better than one, according to a U.S. analysis of past research.
The study, which appeared in JAMA Otolaryngology - Head & Neck Surgery, included 42 studies that compared hearing, speech and quality of life in eligible adults before and after they received a cochlear implant or compared having one versus two functioning implants.
According to the U.S. National Institutes of Health, about 17 percent of U.S. adults have some degree of hearing loss, and the chance of becoming hard of hearing increases with age. Only those with severe hearing loss or deafness, for whom hearing aids haven't work, are considered for cochlear implants.
"Unilateral cochlear implants provide improved hearing and significantly improve quality of life, and improvements in sound localization are noted for bilateral implantation," wrote researchers led by James Gaylor from Tufts Medical Center in Boston.
The studies used in the analysis used a range of tests over different time periods to measure the effects of implantation, so it was difficult to compare them directly, the researchers added. However, almost all the trials looking at the effect of a single cochlear implant showed that people's speech and quality of life improved after implantation.
"Cochlear implantation is just a hugely beneficial procedure for the people who need it. It's almost like magic," said Pamela Roehm, an otolaryngologist from the NYU Langone Medical Center, who wasn't involved in the study.
"Their hearing isn't completely normal, but for speech (and) understanding, it's so good."
Among studies comparing one versus two implants, the majority also found participants were better at communicating and localizing sound when they had a cochlear implant in each ear. It wasn't clear how much of an effect a second implant had on their quality of life, however.
Possible complications of implantation include infection or damage to the device. But Roehm said all things considered, it's a pretty minor procedure.
"It's surgery - you have to have general anesthesia - but as surgeries go, it's not very risky (and) you don't lose a lot of blood," she said. She and her colleagues have put implants into patients over 90 years old, with good results.
The new findings don't mean that deafness has a detrimental effect on quality of life, Gaylor told Reuters Health in an email. He added that for some in the deaf community, cochlear implants are still controversial.
"Our hope is that this paper will allow providers, payers and most importantly patients to ... make more informed decisions about cochlear implantation," Gaylor wrote.