A Case of Acoustic Neuroma Treated with Contralateral Cochlear Implantation

This report describes a case of acoustic neuroma in a patient who underwent contralateral cochlear implantation. A 78-year-old female presented with an acoustic neuroma on the left side and was referred to our department for possible cochlear implantation. She had moderate-to-severe bilateral hearing loss. She had experienced idiopathic sudden sensorineural hearing loss in her right ear over 20 years ago, and her left ear’s hearing level deteriorated gradually following gamma knife therapy for the neuroma. Initial examination showed pure tone audiometry average thresholds of 78.3 dB and 66.7 dB on the right and left ear, respectively, with 25% and 35% speech discrimination rates, respectively. Using bilateral hearing aids, her speech discrimination rate was 45%. Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) scans were unremarkable, except for acoustic neuroma. At 79, she underwent right cochlear implantation using a Cochlear® CI632 implant with full insertion. Postoperatively, she experienced short-term dizziness, but otherwise, her recovery was uneventful. Two years post-implantation, her implantation threshold was 36.7 dB, and her speech discrimination rates were 76% for words and 95% for sentences using CI-2004, the Japanese speech discrimination test. MRI could detect the tumor without being influenced by the artifacts from the implant.