Cochlear implantation in a patient with profound hearing loss with the A1555G mitochondrial mutation

Objective: This study aimed to describe the performance of a cochlear impla nt in a patient with profound hearing loss with the A1555G mitochondrial mu tation. Setting: The study was conducted at two university hospitals. Patient: A 50-year-old Japanese man in whom bilateral profound hearing loss developed after administration of streptomycin at the age of 23 participat ed. The pedigree of the family showed exclusively maternal transmission of hearing impairment. Intervention: Genetic study and auditory rehabilitation with a cochlear imp lant were performed. Results: The A1555G point mutation was identified from the patient's mitoch ondrial DNA. Since activation of the implant, the patient has been using it successfully with a monosyllabic recognition score of 78% using Japanese w ord lists for speech audiometry. Conclusions: The current case indicated that cochlear implantation may be a valuable choice of therapy for the patient with profound hearing loss with the A1555G mutation. The excellent auditory performance with a cochlear im plant suggests that hearing loss associated with this mutation is primarily caused by insult to the cochlear tissue containing rich mitochondria (i.e. , hair cells or stria vascularis or both), not to the cochlear nerve and it s central connections.