Background: High-frequency repetitive transcranial magnetic stimulation of the left dorsolateral prefrontal cortex (rTMS-DLPFC) is an effective treatment for depression. Preliminary studies indicated beneficial effects of rTMS-DLPFC on pain relief in patients treated for depression, and in patients with chronic migraine.
Methods: In this randomized, double-blind, parallel-group, single-center, proof-of-principle clinical trial, we tested the hypothesis that 23 sessions of active rTMS-DLPFC delivered over eight weeks would be feasible, safe and superior to sham rTMS to decrease the number of headache days in 18 patients with chronic migraine without severe depression. Per-protocol analysis was performed.
Results: rTMS-DLPFC applied over eight weeks was feasible and safe in patients with chronic migraine. Contrary to our primary hypothesis, the number of headache days decreased significantly more in the sham group than in the group treated with active rTMS-DLPFC at eight weeks. Average decrease in headache days was >50% in the sham group, indicating a powerful placebo response. Pain intensity improved in both groups to a similar extent.
Conclusions: Positive results of M1 stimulation in other studies, and the absence of significant benefits of active high-frequency rTMS of the DLPFC in the present study, point to M1 as a more promising target than the DLPFC, for larger trials of noninvasive brain stimulation in patients with chronic migraine.
Keywords: Placebo; chronic migraine; dorsolateral prefrontal cortex; pain; transcranial magnetic stimulation.