Cochlear Implants Raise Meningitis Risk

CDC Advises Vaccination, Other Steps to Improve Safety

From the WebMD Archives

July 30, 2003 -- Cochlear implants do indeed increase a child's risk of bacterial meningitis, the CDC confirms.

The FDA last year sent out an urgent warning that the hearing devices seemed to be linked to a dangerous brain infection. The FDA asked the CDC to investigate. The results of that investigation appear in the July 31 issue of The New England Journal of Medicine.

"We found many more cases of bacterial meningitis among children with cochlear implants than among children in the general population," study leader Jennita Reefhuis, PhD, tells WebMD. "But some of these cases may also be due to other risk factors. Meningitis is more common among deaf children. And a lot of children become deaf due to having had meningitis."

"It's still a very uncommon sequel of this type of surgery," George A. Gates, MD, tells WebMD. An editorial by Gates, director of the Bloedel Hearing Research Center at the University of Washington in Seattle, accompanies the CDC report.

After investigating 4,264 children who got the implants, the CDC found only 26 cases of bacterial meningitis.

Nevertheless, Reefhuis' CDC team found that bacterial meningitis occurs 30 times more often in children who get cochlear implants than in other children. And they confirmed another FDA suspicion as well.

'Positioner' Models Further Increase Risk

One of the three manufacturers of cochlear implants -- Advanced Bionics Corp. -- in some models used a component called a positioner to hold the device in place. At the FDA's suggestion, the company voluntarily withdrew this device from the market. And wisely so. The CDC finds that cochlear implants with positioners are linked to four and a half times as many cases of bacterial meningitis as other types of the device.

"We actually don't know how the positioner increases the risk," Reefhuis says. "We don't know what will be the effect over time."

But Gates says there's no reason for people who got the positioner-type implants to have them removed.

Benefit Still Outweighs Risk

Cochlear implants aren't your average hearing aid. Designed for people with deafening nerve damage, the devices are surgically implanted deep within the ear. They turn sound waves into electric signals that are passed to nerve fibers leading into the brain. The devices have restored hearing to many people who can't be helped by other types of hearing aids.

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"Implants have done many wonderful things for children," Reefhuis says. "I've seen tapes of kids who once were deaf and now can sing. Parents should know that cochlear implants can open many, many doors for their child."

It's not an overnight cure. People have to learn how to make sense of the signals a cochlear implant gives to the brain. At first it sounds like a mechanical noise. But eventually the brain adapts and recognizes more normal speech sensations. This takes time and lots of work.

It also takes a lot of money. First, there's the cost of the sophisticated electronic implant. Then, there's the cost of surgery and rehabilitation. The price tag, according to Gates: $60,000 for children and $40,000 for adults.

But Gates notes that this is a lot less than the cost of residential deaf education. That's why the devices are put in as early in life as possible. A window of opportunity for learning speech quickly narrows after the age of 2 years. Though the FDA currently approves the implants for children older than 1 year, Gates suggests that earlier implants may be better.

How to Cut Meningitis Risk

No implant currently on the market is free of meningitis risk. But parents can do a lot to reduce any chance of infection.

The cause of the vast majority of bacterial meningitis infections is a bug called Streptococcus pneumoniae. There's now a vaccine against this germ. The same goes for the next most common meningitis germ, Haemophilis influenzae, or Hib. Children getting cochlear implants of any type should be fully vaccinated against both bugs.

Kids who already have cochlear implants should be vaccinated, too. The CDC has set up a hotline to advise about appropriate vaccinations: (800) 232-2522 (TTY: (800) 232-7889; Spanish: (800) 232-0233).

If your child has a cochlear implant, know the signs of bacterial meningitis. In infants and young children, the early symptoms are fever, irritability, sluggishness, and loss of appetite. In older children, there may be headaches, stiff neck, nausea and/or vomiting, confusion or altered consciousness, and discomfort looking at bright lights.

Some cases of meningitis in kids with cochlear implants seem to follow ear infections. It's a good idea for such children to see a doctor at the first sign of an ear infection.

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Not Just Kids

Cochlear implants can also restore hearing to older adults. And like kids, elderly people may also run a meningitis risk. They should see their doctor about getting the appropriate vaccinations.

WebMD Health News

Sources

SOURCES: TheNew England Journal of Medicine, July 31, 2003. Jennita Reefhuis, PhD, National Center on Birth Defects and Developmental Disabilities, CDC, Atlanta. George A. Gates, director, Bloedel Hearing Research Center, University of Washington, Seattle.
© 2003 WebMD, Inc. All rights reserved.

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