Charcot-Marie-Tooth Disease With Long-Term Follow-Up on Auditory Neuropathy—After Cochlear Implantation Or Hearing Aid Use

Objective To study the pathophysiology of Charcot-Marie-Tooth disease (CMT) with auditory neuropathy (AN) and to follow up cochlear implant or hearing aid use over the long term. Study design Clinical capsule report. Patients Two adult CMT patients with AN. Intervention Cochlear implantation for case 1 and hearing aid use for case 2. Result Case 1 was a 50-year-old man who was diagnosed as having CMT at 15 years of age. He noted his hearing impairment at the age of 22. We considered that he had AN as a complication on the basis of the findings of normal distortion product otoacoustic emission and the absence of auditory brainstem response on both ears. We performed cochlear implantation for his progressive hearing loss when he was 41 years old. His postoperative discrimination scores for words and sentences in the CI-2004 test 4 years after cochlear implantation were 80% and 93%, respectively. His sound discrimination scores were 23/24 in the test with picture matching and 9/24 in that without picture matching 8 years after cochlear implantation.Case 2 was a 38-year-old woman who was neurologically diagnosed as having CMT with AN as a complication on the basis of auditory brainstem response and distortion product otoacoustic emission test findings. During 15 years of follow-up, her discrimination score decreased gradually. She is currently wearing a hearing aid. Conclusions We found a significant improvement in case 1 and a slight increase in hearing level in case 2. The pathoneurological findings of CMT might be either demyelination or axonal degeneration depending on the type of genetic abnormality (e.g., PMP22 and MPZ mutations). The symptoms and courses vary among patients with CMT. Therefore, the selection of an appropriate intervention for hearing loss depending on the severity and course is very important.