Influences on taste in the area of chorda tympani nerve after transtympanic injection of local anesthetic (4% lidocaine).

Transtympanic injection of 4% lidocaine (TTIL) is a unique procedure to treat tinnitus. Some physicians in Japan have been adopting this procedure to treat tinnitus. It has several complications, and safety standards of this procedure have not yet been established. Among the complications, we focused on "transient taste disturbance" after TTIL, because there have been no detailed reports on this subject. We examined the taste sensation in the area of the chorda tympani nerve before and after TTIL by applying electrogustometry with dB scale (EGM) and filter-paper disc method (FPD method). For a control, we used transtympanic injection of 0.4% dexamethasone (TTIS). After TTIL, transient pathway insufficiency on chorda tympani nerve was observed both in the EGM and the FPD methods, but this pathway insufficiency recovered within 24 h. Some patients felt spontaneous abnormal bitter taste sensation in the oral cavity after TTIL, but the reason for this phenomenon could not be determined.