ObjectiveReport a case of localized necrotizing meningoencephalitis as the cause of functional hearing loss after cochlear implant (CI) surgery.Case reportA 12-year-old with bilateral CI presented to our quaternary center due to severe functional hearing loss after 11 years since left ear CI surgery. CT with contrast was conducted showing a CPA tumor-like mass. Pre-operative computed tomography (CT) scans and magnetic resonance imaging (MRI) performed at the age of 1 year showed no inner ear abnormalities and in particular no evidence of a tumor in the cerebellopontine angle (CPA).ConclusionFollowing removal of the CI and the mass, histopathological, immunohistochemical and cultural examinations revealed a necrotizing meningoencephalitis, with the CI electrode as the focus.