The effect of intratympanic gentamicin for treatment of M,niSre's disease on lower frequency hearing

Background The intratympanic application of the ototoxic aminoglycoside gentamicin has shown promising results as an ablative treatment for vertigo associated with M,niSre's disease. Objective To evaluate the efficacy and safety of intratympanic gentamicin and to specifically analyse the effect of this treatment on high and low hearing frequencies in patients with unilateral definite M,niSre's disease. Method Subjects were treated with intratympanic gentamicin and were evaluated on vertigo, tinnitus, mean pure tone audiometry threshold and speech discrimination score. Subjects were followed for evaluation for up to 2 years after treatment. Results The number of vertigo spells per month decreased and subjects experienced less tinnitus. During follow up there was an increase of hearing loss in the low (0.25-, 0.5-, 1-kHz) frequency range (13.3 dB; p = 0.03). There was no significant increase of hearing loss in the high (2-, 4-, 8-kHz) frequency range. A clinically significant change in speech discrimination score was found in 50 % of the subjects. Conclusion Our results indicate that intratympanic gentamicin especially affects the mean pure tone audiometry threshold in the low frequency range, which may have clinical implications. Though many of our results are (statistically) substantial the study was limited by the small cohort size.