Children with a cochlear implant have a greater risk of developing pneumococcal (Streptococcus pneumoniae) meningitis compared to children in the general population, according to a study conducted by the Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA) and others published in the July 31 issue of The New England Journal of Medicine (NEJM). Additionally, children with a specific type of cochlear implant that had an extra piece called a "positioner" had 4.5 times the risk of developing meningitis compared to recipients of other cochlear implant types. The manufacturer voluntarily recalled the device with the positioner last year.
The CDC and FDA began investigating this possible link between the implants and meningitis in the summer of 2002 after receiving reports of bacterial meningitis among recipients of cochlear implants. As soon as the FDA became aware of a possible association between cochlear implants and bacterial meningitis, the agency issued a public health Web notice and began working with manufacturers of cochlear implants to determine the nature and scope of the problem. As a result, the company that made the implant with the extra positioner voluntarily withdrew that product from the market.
"This study is the result of excellent collaboration between the CDC, FDA and health departments of 36 states, Chicago, New York City and Washington, D.C," said HHS Secretary Tommy G. Thompson. "The government quickly identified a health problem, took immediate steps to find the cause, and alerted individuals with cochlear implants and their physicians to measures they could take to protect against it."
The study authors note that individuals who are candidates for cochlear implants may have factors that increase their risk of meningitis compared to the general population even prior to being implanted with the device. However, the study was not designed to determine the risk due to these preexisting factors.
"These findings have important implications for children with cochlear implants. Most bacterial meningitis is vaccine-preventable so children who have a cochlear implant, or who will receive one, should have all recommended childhood vaccinations, including age-specific pneumococcal vaccinations for high-risk children," said Dr. Julie Gerberding, CDC Director.
"Working closely with CDC's network for monitoring infection outbreaks is an important part of how we monitor the safety of medical products in use in the population," said FDA Commissioner Dr. Mark. B. McClellan. "In this case, we identified a heightened risk of meningitis that demanded prompt action, and the FDA was able to take it."
Nearly 10,000 children and 13,000 adults in the United States with severe-to-profound hearing loss have a cochlear implant. The implant is an electronic device containing electrodes that are surgically inserted into the cochlea (inner ear) to activate nerve fibers and allow sound signals to be transmitted to the brain. It can help children with hearing loss perceive sounds and learn to speak.
The study group involved 4,264 children who received a cochlear implant in the United States between January 1, 1997 and August 6, 2002, and who were younger than age 6 at the time of the implant.
A total of 29 cases of bacterial meningitis were identified in 26 children (three children had two episodes of the illness). Fifteen children had meningitis caused by Streptococcus pneumoniae. Less than one case of the disease would be seen in a group this size, during the same time period, based on the rates in the general population.
Nine of the 29 cases occurred within a month following the cochlear implant surgery, the remaining 20 occurred up to 36 months later.