Cochlear Implants and Reports of Associated Health Risks
There is concern that cochlear implant recipients may be at increased risk to develop bacterial meningitis. Based on what is currently known, the risk of meningitis is small, especially in the United States where there have been fewer reported cases. However, the relationship between cochlear implantation and bacterial meningitis is not fully understood. While it is clear that there are special populations of patients who may receive an implant who are at increased risk to contract meningitis, it is not yet certain whether, or to what degree, a cochlear implant is in itself an independent risk factor for bacterial meningitis. In order to better understand the relationship between meningitis and cochlear implants, the Center for Disease Control has recently initiated a study of implant recipients.
Until more information is available, from a patient safety standpoint it is wise to proceed as if an increased risk may be present. For this reason, many physicians are recommending a program of vaccination for their cochlear implant recipients and candidates.
In the general population, people at increased risk for bacterial meningitis include the very young (especially children under two years) and the elderly (over 65). Medical problems such as immune deficiencies also increase the likelihood of meningitis. Among the deaf, individuals with abnormal temporal bone anatomy may experience a cerebral spinal fluid (CSF) leak spontaneously or at the time of implant surgery. The presence of a CSF leak is associated with significant risk of bacterial meningitis.
For example, the author evaluated a one year old who had been recently deafened by pneumococcal meningitis. Radiologic evaluation revealed the presence of a cochlear malformation of one ear as well as evidence of an active CSF leak. The leak was the cause of the meningitis that resulted in loss of hearing in the child's only hearing ear. A more common scenario is the occurrence of a CSF leak during implantation of a malformed cochlea. This situation is well known in the cochlear implant literature and surgeons can successfully accomplish both implantation and closure of the leak.
The occurrence of Hemophilus influenza meningitis, previously a significant problem, has dramatically declined since the 1980's when it became routine for H. influenzae conjugate vaccine to be given to children under age five years in this country. In the United States, pneumococcal disease remains the most common cause of meningitis and, therefore, should be the focus of any vaccination program to reduce the risk of bacterial meningitis. However, until recently pneumococcal vaccines were not effective in children under two years, the most vulnerable age group. Fortunately, in 2000 Prevnar, a highly safe and effective vaccine for very young children, became available. Since its introduction, Prevnar has been given routinely to all infants and children under two years as well as to children under five years known to be at increased risk for meningitis. Prevnar has dramatically reduced the incidence of both pneumococcal meningitis and childhood deafness due to this infection.
Many implant centers are now ensuring that both implant recipients and candidates are aware of the potential benefit of vaccination, especially against pneumococcal disease. Our implant center now recommends that all pediatric candidates and recipients receive pneumococcal vaccination as well as any other age appropriate vaccines that might decrease the likelihood of meningitis. This recommendation applies to all of our patients regardless of age, health status or type of device.