Kallio H, Niskanen ML, Havia M, Neuvonen PJ, Rosenberg PH, Kentala E.

Department of Anaesthesiology and Intensive Care Medicine.

BACKGROUND: I.V. lidocaine has been used to ameliorate tinnitus, but in general its effect has been limited. The longer acting local anaesthetic ropivacaine may be more effective.

METHODS:  A total of 19 randomized, double-blind, cross-over study patients suffering from chronic tinnitus were given a 30 min i.v. infusion of ropivacaine or lidocaine 1.5 mg kg(-1) at an interval of 2-3 months. The intensity of tinnitus was evaluated on tinnitus handicap inventory (THI) scale and on the visual analogue scale (VAS). Plasma ropivacaine and lidocaine concentrations were determined.

RESULTS: In both treatments, the infusion decreased the VAS score significantly. At the end of infusion, a >/=50% reduction in VAS score was observed in five patients by ropivacaine and in one patient by lidocaine, but this effect was sustained for 1 h only in three patients. However, the THI scores did not differ significantly within or between treatments. On the post-infusion day, three patients after ropivacaine and five after lidocaine treatment had >/=30% improvement in the THI score. Four weeks later, one patient after ropivacaine and two after lidocaine had a >/=30% reduction in the THI score. One patient developed seizures soon after ropivacaine infusion from which he recovered uneventfully. His plasma concentration of ropivacaine was 1817 ng ml(-1). The highest individual ropivacaine and lidocaine concentrations were 3483 and 1680 ng ml(-1), respectively.

CONCLUSIONS:  Temporary clinically significant alleviation of tinnitus was observed only in a few individuals after both i.v. ropivacaine and lidocaine. The toxicity of ropivacaine limits its usefulness.