Neurootological Study on the Effect of Intravenous Lidocaine on Tinnitus in a Sound-proof Room

Abstract

The effects of intravenous administration of lidocaine (1 mg/kg) on tinnitus perceived by normal adults in a sound-proof room were compared with those in patients with hearing disorders. Intravenous administration of lidocaine caused a 50-100%reduction of subjective loudness of tinnitus in 36 of 68 patients, but in only 2 of 19 normal subjects in the sound-proof room. It was interesting that subjective loundness of tinnitus was enhanced in 15 of the latter. Lidocaine had no effect on hearing threshold. However, hearing threshold of the subjects with tinnitus in the sound-proof room, who exhitited increased loudness, revealed a tendency to rise at a pitch of their tinnitus.
These results suggest that the generation of this type of tinnitus stems from change of activity of some inhibitory neurons. This study showed that th e effect of lidocaine differed with the kind of tinnitus.
Thus intravenous administration of lidocaine may be useful for differential diagnosis of tinnitus.