Reducing pain and unpleasantness during repetitive transcranial magnetic stimulation

Repetitive transcranial magnetic stimulation (rTMS) is associated with significant scalp discomfort under the coil for a high percentage of participants, especially with high stimulation intensities (100% of motor threshold or higher) or frequencies (1 Hz or greater). Some patients in rTMS clinical trials have been unable to tolerate the pain and have dropped out. There seem to be no published studies of strategies to reduce the localized pain and discomfort associated with rTMS. Thus, the authors conducted preliminary pilot trials of 4 different strategies for managing discomfort associated with left prefrontal rTMS. Healthy adults rated the painfulness and unpleasantness of left prefrontal rTMS (10 Hz; 5 seconds, on; 30 seconds, off; at 100% and 120% of resting motor threshold) before and after (1) topical application of a eutectic mixture of local anesthetics cream, (2) scalp injection of lidocaine, (3) scalp injection of lidocaine and epinephrine, and (4) with or without 3 x 3-in thin foam sheets between the coil and scalp. The discomfort produced by rTMS under these experimental conditions was compared with the discomfort produced by stimulation with the same parameters without the interventions. Localized anesthetic injections were associated with a significant decrease in pain intensity and unpleasantness, whereas the eutectic mixture of local anesthetics cream had no effect on rTMS-related discomfort. The use of foam sheets was associated with a slight but noticeable decrease in pain intensity and unpleasantness. More systematic research is needed on the effectiveness of different strategies for reducing rTMS-related pain and discomfort.