Bacterial Meningitis in Children with Cochlear Implants

Thomas J. Balkany, M.D., FACS, FAAP (Chair, Hearing and Equilibrium Committee)
Noel L. Cohen, M.D., FACS
Harold C. Pillsbury, M.D., FACS (Past President, AAO-HNS)
Barry E. Hirsch, M.D., FACS ((Chair, Implantable Hearing Devices Sub-Committee)

Note: This commentary refers to an important article on meningitis in children with cochlear implants published recently in the NEJM (July 31, 2003) by Reefhuis et al. The work was performed by the CDC, FDA, and state health departments.

Reefhuis et al (1) have provided a service to otolaryngologists, pediatricians and other professionals who care for hearing impaired children. In carefully evaluating 4264 children implanted before age 6, they found an incidence of meningitis of just over ½ of 1% (0.006). While this number may seem small, many such cases may be preventable in the future. The Advanced Bionics Clarion with Positioner was associated with a higher incidence of meningitis than other implants and is now off the market. That alone may reduce the incidence of meningitis by nearly half. In addition, careful compliance with CDC recommendations for immunization (pneumococcus and h. influenza) along with aggressive antibiotic treatment of otitis media and other bacterial infections will further reduce the incidence.

One weakness of the study is the inference that children with implants are at a 30 fold increased risk of meningitis. Unfortunately, a convenience control group (the general under-six year old population) rather than a realistic control (hearing-impaired, non-implanted children) had to be used because the incidence of meningitis in the latter is not readily available.

Hearing-impaired children are at increased risk of meningitis, even without implants. This is evidenced in the study by two findings:

• 23% of the implanted children had meningitis BEFORE receiving their cochlear implant. This also places them at high-risk for another episode.
• 11.5% of the implanted children had labyrinthine dysplasia (Mondini and similar deformities). This too is well known to be associated with meningitis, with or without implants.

In a separate report (2), dysplastic temporal bones from a child with meningitis after implantation were studied post-mortem. Surprisingly, the non-implanted ear was the culprit, with infection extending to the meninges. The implanted ear and the device itself were in no way involved in the infection.

Nonetheless, the American Academy of Otolaryngology-Head and Neck Surgery strongly supports the recommendations of CDC and FDA. All children should be immunized for pneumococcus and h.influenza. Otitis media and other bacterial infections should be treated aggressively. This is especially true for hearing-impaired children, those with labyrinthine dysplasia, and even more so for those with cochlear implants. Otolaryngologists should counsel parents and other healthcare providers in this regard. When performing cochlear implantation, every effort should be made to minimize trauma (avoidance of overly large cochleostomy and over-insertion of the electrode after resistance is met) and to seal the cochleostomy with a circumferential tissue graft around the electrode.

INSERT Reefhuis Supplementary Appendix 2: Pneumococcal Immunization Schedule (with permission).

REFERENCES

1. Reefhuis J, Honein MA, Whitney CG, Chamany S, Mann E et al. Risk of Bacterial Meningitis in Children with Cochlear Implants. New England J. Med 2003; 349:433-443.
2. Suzuki C, Sando I, Fagan JJ et al. Histopathological features of a cochlear implant and otogenic meningitis in mondini dysplasia.
   Arch Otolaryng Head Neck Surg 1998: 124;462-466.

Three Sentences for Website

1. The recent paper by Reefhuis et al in NEJM (July 31, 2003), on work performed by CDC and FDA, shows that meningitis occurred in one-half of 1 percent of children under age 6 who have cochlear implants.
2. Unfortunately, the relative risk in the study may be exaggerated because the control group was normal children rather than hearing impaired children, who have a higher risk of meningitis, even without cochlear implants (due to dysplasia, prior meningitis, etc.)
3. AAO-HNS recommends that all children be immunized for pneumococcus and h.influenza, and treated appropriately for bacterial infections, especially those with dysplasia and more so those with implants.

ENET News

Refer to: www.cdc.gov/ncbddd
Reference: Coleen Boyle, Ph.D.; J. Reefhuis, Ph.D. 404-498-3800 or 404-498-3917

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