Sensorineural hearing loss in MELAS syndrome--case report.

A mitochondrial tRNA mutation at nucleotide 3,243 is known to be found in most patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes). We report a 30 year-old female patient of MELAS, diagnosed 5 years ago, who presented herself to our ENT outpatient department because of her bilateral tinnitus and progressive hearing impairment since 4 years ago. Two sequential pure tone audiograms showed bilateral symmetrical progressive sensorineural hearing loss, especially in the high frequency area in 1993 and 1996. The pure tone average was R-45 dB, L-47 dB in 1993 and R-62 dB, L-67 dB in 1996. Hearing loss is an important feature in MELAS syndrome and reported to be seen in about 30% of patients. It is often the first clinical symptom, too. In any case, mitochondrial cytopathies need to be considered by the otologist in forming a diagnosis of sensorineural hearing loss (SNHL), particularly in cases, which present adult-onset progressive hearing loss and neurologic symptoms before 50 years of age.