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19-01-2012 | Surgery | Article

Cochlear implants for post-meningitis deafness offer good outcomes


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MedWire News: Technologic advances in cochlear implants have resulted in good outcomes for patients who develop hearing loss following meningitis, say researchers.

Their conclusion is based on a retrospective chart review of 20 adults (mean age 43 years) who suffered profound hearing loss as a complication of meningitis between 1990 and 2008.

"Bacterial meningitis is one of the most common causes of acquired bilateral severe/profound sensorineural hearing loss in adults and children," explain Isabelle Mosnier (Hôpital Beaujon, Clichy, France) and co-workers writing in the European Archives of Otorhinolaryngology.

"Cochlear implantation provides auditory rehabilitation, but only a few studies have analyzed the postoperative performance."

To address this shortfall, the team compared hearing outcomes in the post-meningitis group with those in a control group of 46 adults who received cochlear implants for hearing loss caused by factors other than meningitis.

The two groups had comparable speech scores before they received a cochlear implant, Mosnier et al note. Speech scores were calculated from each patient's comprehension of 10 disyllabic words played at 65 dB, with and without lipreading.

After receiving the cochlear implant, speech scores improved in both groups.

However, the improvement in speech scores was significantly greater in controls as compared with post-meningitis patients. This held true both with and without lipreading, and the difference persisted at 6, 12, 24, and 36 months post-implantation.

To understand the reasons for the difference, Mosnier et al analyzed temporal trends. They found that the performance of cochlear implants rose over time, with patients implanted after 2001 showing a greater magnitude of improvement in speech scores than patients implanted before 2001.

Indeed, after 2001, patients showed a similar magnitude of improvement in speech scores irrespective of whether their hearing loss was caused by meningitis or other factors.

In terms of complications, one patient experienced cochlear ossification, which led to short-circuits in the electrode array and ultimately to implant failure.

Mosnier et al say their study demonstrates that advances in cochlear implant technology and coding strategy have improved hearing outcomes and that post-meningitis patients with full electrode insertion now reach the performance of nonmeningitis patients.

Noting that cochlear ossification can compromise outcomes, they propose a strategy of early simultaneous bilateral implantation for post-meningitis deaf patients.

"In case of bilateral total ossification, poor and inconstant results are reported in studies," they add. "Auditory brainstem implant could be an efficient tool for auditory rehabilitation in these patients."

By Joanna Lyford

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