Placebo effect in tinnitus management.

Masking devices, lidocaine, and analog oral forms of lidocaine have all been reported as being effective forms of therapy to relieve tinnitus. Many studies, however, have used single-blind protocols and were possibly biased by placebo effects. To investigate the contributions of a placebo effect in clinical tinnitus studies, 25 tinnitus patients who had received a placebo injection in a previous double-blind lidocaine study were contacted on the pretense that they would receive a test dose of lidocaine; the 20 who responded were included in this study. A 5 cc bolus of placebo saline solution instead of lidocaine was then administered to each patient. Forty percent of the patients reported a change in their tinnitus following the placebo injection. The results of this study serve to point out the inherent flaws in straight clinical trials, and that the success rates achieved in such uncontrolled clinical investigations may be biased by the placebo effects.