Effects of valproic acid on hearing in epileptic patients

Since some case reports about the ototoxicity of valproic acid have been published, probable adverse effects of valproic acid on hearing in the epileptic patients became a subject of interest. We wanted to investigate if ototoxicity occurs in pediatric epileptic patients using VPA for long terms.

Twenty-one epileptic patients who have been using valproic acid at least for 6 months as monotherapy and 21 age-sex matched controls were included in the study. Audiometric tests were performed to all patients between the frequencies of 125 and 16,000 Hz. The effects of dosage, duration of therapy and serum levels of the VPA, on the audiometric results were investigated and the audiometric results were compared between the groups.

There was no difference in hearing thresholds of the groups between 125 and 16,000 Hz frequencies. Relation could not be established between the duration of VPA therapy, dosage of the drug, blood level of drug, age and sex of the patients and the auditory signs.

Although we could not find any deleterious effect of VPA on hearing thresholds in our patient series, we think it is useful to perform audiometric tests at intervals while VPA is being used for long periods, considering the presented case reports about sensorineural hearing loss.