Treatment of tinnitus with lidocaine and tocainide.

The efficacy of lidocaine and tocainide in the rational treatment of tinnitus aurium was evaluated in a double-blind randomized cross over study against saline as placebo. Forty patients with severe long lasting (more than six months) tinnitus and sensorineural hearing loss were included in the study. In 24 patients treated with lidocaine (loading dose: 3 mg/kg body weight in 10 min; maintenance dose: 1 mg/kg in 20 min), in 19 patients treated with tocainide infusion (750 mg in 30 min), and 10 patients treated with tocainide orally (400 to 2,400 mg per day), tinnitus intensity was reduced by more than 50%, compared with placebo (designated as a positive result). In some patients, ABRs showed prolongation of interpeak latencies (IPLs) indicating a retrochlear site of drug action. This hypothesis is supported by our own animal experiments with lidocaine in rabbits. IPLs showed a dose dependent reversible prolongation without hearing loss.