ミトコンドリア脳筋症例に対する人工内耳

Abstract

Kearns-Sayre syndrome (KSS) is one of a mitochondrial disease characterized by progressive eye disorders, such as pigmentary retinopathy, and complete heart blockage. A recent study revealed that the etiology of this syndrome involves sporadic large scale rearrangements of mitochondrial DNA. Other neurologic symptoms are frequently associated with this syndrome, and hearing loss is the other main symptom. At the age of 37 years, this female patient began to suffer progressive hearing loss, and eventually became completely deaf. MRI imaging showed diffuse, abnormally high signals in the brain white matter, in T2-weighted images. Further neurological examination revealed eye abnormalities, and a genetic analysis confirmed a diagnosis of KSS. In this case, no sensory agnosia or other focal signs of disorder in the brain cortex were found, and the electrophysical criteria for cochlear implant were fulfilled. Cochlear implantation was performed on May 19, 1995. Post-operatively, the patient underwent vowel and consonant recognition tests. The patients scored well with an accuracy of 75% for vowels and 36% for consonants. The accuracy of vowel and consonant recognition with lip reading was elevated to 100% and 72%, respectively. Sound recognition in this patient seemed to be quite high compared to that reported in other implanted patients. The excellent results obtained in this KSS patient suggest pure neural deafness, and raise the possibility of cochlear involvement in this condition.