Clinical and audiological follow up of a family with the 8363G>A mutation in the mitochondrial DNA

Hearing loss is relatively common in mtDNA-related disorders. While auditory function has been assessed fully in the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, few studies have investigated the degree of progressive hearing deficit in individuals bearing other mtDNA mutations. We performed a 4-year clinical and audiological follow up in a family carrying the 8363G>A mutation in the mitochondrial transfer ribonucleic acid lysine (tRNA(Lys)) gene who displayed a progressive neuromuscular disease. In addition to pure tone audiometry, we considered distortion products of otoacoustic emissions, a sensitive indicator of cochlear dysfunction, as well as brainstem auditory evoked responses. A generalized increase in the auditory threshold at follow up, indicating a cochlear impairment in three cases, was noted. Distortion products of otoacoustic emissions may reveal sub-clinical cochlear dysfunction, even in oligosymptomatic patients. A complete and periodical assessment of the hearing function should be encouraged in asymptomatic relatives of patients carrying the tRNA(Lys) 8363G>A mutation.

DiFabio R, Santorelli FM, Nola G, Cricchi F, Masi R, Ingrosso A, Fattori F, Carrozzo R, Vanacore N, Pierelli F, Ralli G, Casali C.

Department of Neurology and ORL, Sapienza University of Rome ICOT, Polo Pontino, 04100 Latina, Italy.

PMID:19233651 [PubMed – indexed for MEDLINE]