Necrotizing meningoencephalitis mimicking cerebellopontine angle tumor as late complication following cochlear implantation.

We describe for the first time localized necrotizing meningoencephalitis as the cause of functional hearing loss, facial nerve palsy, and vertigo after cochlear implant (CI) surgery. Magnet resonance imaging (MRI) and computed tomography scans before CI surgery and after 3 years showed no abnormalities, especially no evidence of a tumor in the cerebellopontine angle (CPA). Due to recurrent facial nerve palsy the CI was explanted after 5 years in order to be able to visualize the CPA without artifacts caused by the CI in MRI scans. The MRI scans now showed a tumor in the CPA. Following removal of the tumor, histopathological and immunohistochemical examination revealed a necrotizing meningoencephalitis, with the CI electrode as the focus.