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

The cerebral perfusion of a 55-year-old female patient with chronic tinnitus was investigated quantitatively by single photon emission computed tomography (SPECT) with the xenon133 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 perfusion was identical on both sides except for increased perfusion in the auditory cortex, especially on the right side when tinnitus lasted during the first measurement. The second investigation under treatment with lidocaine and during the tinnitus-free interval showed a decrease of the global cortical perfusion with a slightly higher value at the temporal cortex bilaterally. In comparison to the first investigation, a difference between right and left auditory cortex could no longer be demonstrated, and also the difference between regional and global perfusion decreased. A cerebral effect under treatment of tinnitus with lidocaine was shown by the quantitative measurement of brain perfusion. It is debatable whether this effect on cerebral activity results from the medication or as a reaction to the tinnitus-free interval.