Tinnitus is perception of sound without the presence of an external acoustic stimulus.
Approximately 50 million Americans experience chronic tinnitus and of these, 10 million have
bothersome tinnitus. The tinnitus research literature suggests that NMDA receptor antagonists
may prove to be useful in reducing tinnitus. Nitrous oxide, a member of the NMDA receptor
antagonist class, is a widely-used general anesthetic and sedative with a proven safety
profile. The investigators hypothesized that the administration of nitrous oxide, an NMDA
receptor antagonist, may be effective in treatment of tinnitus. The study design was a
randomized placebo-controlled crossover trial.