Cochlear implantation of a patient with a previously undescribed mitochondrial DNA defect.

Mitochondrial DNA (mtDNA) defects are responsible for symptom complexes that are characteristically heterogeneous but are typically represented by muscle weakness and neurological deficits. One common feature of mitochondrial disease is deafness. This report details the assessment and outcome of a patient with a previously undescribed mtDNA rearrangement who underwent cochlear implantation. The patient shows a marked improvement in sentence recognition tests and recognition of environmental sounds. Patients with profound sensorineural hearing loss due to mtDNA defects should be considered as candidates for cochlear implantation when they no longer benefit from conventional hearing aids.