Audiological manifestations in mitochondrial encephalomyopathy lactic acidosis and stroke like episodes (MELAS) syndrome.

OBJECTIVES

Reports of audiological manifestations in specific subgroups of mitochondrial disorders are limited. This study aims to describe the audiological findings in patients with MELAS syndrome and m.3243A>G mutation.

PATIENTS &

METHODS

Audiological evaluation was carried out in eight patients with confirmed MELAS syndrome and m.3243A>G mutation. The evaluation included a complete neurological evaluation, pure tone audiometry (n=8), otoacoustic emissions (n=8) and brainstem evoked response audiometry (n=6), magnetic resonance imaging (n=8) and muscle biospy (n=6).

RESULTS

Eight patients (Age range: 5-45 years; M:F-1:3) including six children and two adults underwent formal audiological evaluation. Five patients had hearing loss; of these two had "subclinical hearing loss", one had moderate and two had severe hearing loss. The abnormalities included abnormal audiometry (n=5), otoacoustic emission testing (n=7) and absent brainstem auditory evoked responses (n=1). The findings were suggestive of cochlear involvement in four and retrocochlear in one.

CONCLUSIONS

This study shows that hearing loss of both cochlear and retrocochlear origin occurs in patients with MELAS and may be subclinical. Early referrals for audiological evaluation is warranted to recognize the subclinical hearing loss in these patients. The therapeutic implications include early interventions in the form of hearing aids, cochlear implants and cautioning the physicians for avoidance of aminoglycosides.