Meningitis Linked to Cochlear Implants Recipients and Candidates May Benefit from Vaccination Features
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Features  |   September 01, 2002
Meningitis Linked to Cochlear Implants
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Hearing Aids, Cochlear Implants & Assistive Technology / Features
Features   |   September 01, 2002
Meningitis Linked to Cochlear Implants
The ASHA Leader, September 2002, Vol. 7, 1-13. doi:10.1044/leader.FTR3.07172002.1
The ASHA Leader, September 2002, Vol. 7, 1-13. doi:10.1044/leader.FTR3.07172002.1
The U.S. Food and Drug Administration (FDA) issued a notice about a possible link between cochlear implants and bacterial meningitis, although the exact cause of meningitis has not been established.
Of approximately 60,000 cochlear implant recipients worldwide, 52 adults and children between 21 months and 72 years of age have contracted meningitis. A total of 12 known deaths have resulted, according to the most recent FDA data.
To study the incidence of meningitis in North America, otolaryngologists Noel Cohen of New York University and Thomas Balkany of the University of Miami surveyed approximately 400 implant centers. Although the survey is ongoing, so far they have received 130 responses to the survey from 401 surgeons who performed approximately 18,000 of 24,000 implants. The survey identified 24 cases of meningitis, which resulted in the deaths of two preschoolers. The survey results are being shared with the FDA and Centers for Disease Control and Prevention (CDC) and will be made available to the public.
“A cluster of recent meningitis cases were identified among cochlear implant recipients,” Balkany said. From 1984 to 1999, the incidence of meningitis in the United States was sporadic, but since 2000, eight cases have so far been identified.
Within the general population, bacterial meningitis is a very rare and potentially fatal infection of the tissue layers surrounding the brain and cerebrospinal fluid. The most common form of bacterial meningitis in North America is pneumococcal meningitis, and 90% or of all cases—approximately 7 out of every 100,000—occur each year in children under 5 years of age. Young children under age 2 and the elderly are most vulnerable to the disease.
Assessing The Risk
Among implant recipients, the incidence of meningitis is similar to the general population, especially if age is considered, Balkany said. “The data support incidence figures in the order of 10 per 100,00 per year,” he said. “An exception may be the two-part electrode which recently has been voluntarily removed from the market. But even without an implant, deaf children are at higher risk.”
Among implant recipients, the onset of meningitis symptoms ranged from less than 24 hours to more than 5 years post-implant, although most cases occurred within months of receiving the implant. Because of the delay in the onset of meningitis, implant teams should examine their patient base for unreported cases, Balkany suggested.
Most of the reported cases occurred in children under age 5, although some adults have developed meningitis. The vaccination status was available in six cases, and none of these patients were vaccinated. Prior to the February 2000 FDA approval of the Prevnar pneumococcal vaccine, there was no effective vaccine for children younger than 2 years. The current vaccine shortage led the CDC to revise its vaccination guidelines, although the revisions do not change the initial recommendation for vaccinating children younger than age 5 at high risk of pneumococcal disease.
The recent increase in bacterial meningitis among cochlear implant recipients in North America reflected a worldwide trend and prompted an ad hoc meeting in July of European otolaryngologists in Amsterdam to exchange information with American colleagues and make recommendations about patient management.
The otolaryngologists found a greater incidence of meningitis among cochlear implant recipients with who use a two-component electrode array which includes a silastic positioner that places the electrode close to the auditory nerve, and recommended that the positioner be discontinued. Regulatory agencies in France, Germany, Spain, and the United States accepted the recommendations.
“The relationship between the positioner and meningitis is only inferential at this time, and the exact mechanism is unclear,” Balkany said. “It has been hypothesized that the two-part electrode might let in bacteria from a middle-ear infection, and that additional cochlear damage caused by inserting the positioner might act as a nidus for infection.”
Predisposing Factors
Although the cause of meningitis in cochlear implant recipients has not been established, several predisposing factors have been identified:
  • Prior history of meningitis. Meningitis is a leading cause of deafness in children, and a primary reason they receive cochlear implants. These children have an increased risk of subsequent episodes of meningitis compared to the general population. Of approximately 5,000 young children implanted in the United States, approximately 400 had meningitis prior to cochlear implantation, and 17 contracted it afterwards, Balkany said.

  • Congenital cochlear abnormalities. Patients who have abnormal cochlear structures, including Mondini malformation, cerebrospinal fluid (CSF) leak, enlarged vestibular aqueduct syndrome (LVAS), and common cavities, may be at greater risk.

  • Otitis media. In some of the reported cases, patients may have had overt or sub-clinical otitis media prior to cochlear implant surgery or before meningitis developed. Children with cochlear implants who develop symptoms or signs of acute otitis media should be treated promptly, according to the FDA.

Other predisposing factors include immunodeficiency, surgical issues such as an incomplete seal of the cochleostomy, or the cochlear implant itself, which can act as a conduit for infection in patients who have bacterial illnesses because it is a foreign body.
Patient Education
After the FDA issued a notice in July, implant centers across the country provided information to patients and candidates. The University of Miami and New York University implant teams developed recommendations, distributed written information, provided forums, and spent time with concerned patients. “Our greatest calling is to protect our patients, inform them, and provide guidance,” Balkany said. “It’s important to provide information, reassurance, and to be available to speak to anyone—patient, family, or primary care physician—who needs information.”
Centers received information from each device manufacturer concerning the possible association of meningitis and cochlear implantation, said Karen Iler Kirk, of the Indiana University School of Medicine and chair of ASHA’s work group which is developing a document on cochlear implants. “We prepared a letter for all recipients and candidates sharing information from the FDA Web site so they can monitor future updates.” The implant manufacturers also provided information to recipients and candidates.
“We are changing the way we counsel patients prior to implantation so that they are told about this possible association and the availability of vaccinations,” Kirk said. Although vaccination is not required prior to surgery, she said that patients are encouraged to discuss it with their family physician.
Other implant centers, such as the University of Miami, will routinely recommend immunization of children under age 5 and patients at higher risk for meningitis, Balkany said.
The FDA stated that cochlear implant recipients and candidates may benefit from vaccination, and immunization status should be ascertained for patients with an implant and for those undergoing surgery. Two cochlear implant manufacturers developed a program to reimburse current and future cochlear implant recipients for any unreimbursed medical expenses incurred in obtaining vaccination against bacterial meningitis.
Reporting Meningitis
Clinicians are encouraged to be alert to meningitis among implant recipients and report cases to the device manufacturer or to MedWatch, the FDA’s voluntary reporting program. Early symptoms of meningitis include fever, irritability, lethargy and loss of appetite in infants and young children. Older children and adults may have a headache, stiff neck, nausea and vomiting, and confusion or alteration in consciousness. If caught early, meningitis can be treated with antibiotics, but if diagnosis is delayed, the infection can be fatal.
The link to meningitis should not dissuade clinicians from referring patients to implant centers, Kirk said. “Overall, cochlear implants have proven to be an effective medical intervention for children and adults with severe-to-profound hearing loss and have had a substantial impact on patient’s quality of life.”
For more information about meningitis and cochlear implants, contact Gail Linn by phone through the ASHA action center at 800-498-2071, ext. 4112, or by email at glinn@asha.org.
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September 2002
Volume 7, Issue 17