The effect of lidocaine on chronic tinnitus: a quantitative cerebral perfusion study

The cerebral perfusion of a 55-year-old female patient with chronic tinnitu s was investigated quantitatively by single photon emission computed tomogr aphy (SPECT) with the xenon(133) inhalation method. The first investigation was performed under standard conditions, the second during suppression of tinnitus with intravenous injection of lidocaine. As a reference a healthy volunteer was included under the same conditions. The global cortical perfu sion was identical on both sides except for increased perfusion in the audi tory cortex, especially on the right side when tinnitus lasted during the f irst measurement. The second investigation under treatment with lidocaine a nd during the tinnitus-free interval showed a decrease of the global cortic al perfusion with a slightly higher value at the temporal cortex bilaterall y. In comparison to the first investigation, a difference between right and left auditory cortex could no longer be demonstrated, and also the differe nce between regional and global perfusion decreased. A cerebral effect unde r treatment of tinnitus with lidocaine was shown by the quantitative measur ement of brain perfusion. It is debatable whether this effect on cerebral a ctivity results from the medication or as a reaction to the tinnitus-free i nterval.