Treatment of intractable neuropathic pain by high-frequency repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex

In the previous report, the authors reported that navigation-guided 5-Hz repetitive transcranial magnetic stimulation (TMS) of the primary motor cortex relieved intractable neuropathic pain. However the ideal parameters and indications of rTMS for pain are not yet clear. The present study evaluated differences in the efficacy of rTMS with respect to stimulation frequencies and to etiology. Thirteen patients with intractable neuropathic pain were divided into two groups according to the lesions causing pain; a cerebral lesion group and a non-cerebral lesion group. 10-, 5- and 1-Hz rTMS of the primary motor cortex and sham stimulation were applied to patients in each group at random. The effect of rTMS for pain was evaluated by a visual analogue scale. 10- and 5-Hz rTMS of the primary motor cortex, compared with sham stimulation, significantly reduced pain for up to 180 minutes, whereas 1-Hz rTMS was not effective. 10-Hz rTMS was suggested to be more effective than 5-Hz rTMS. 10- and 5-Hz rTMS were more effective in the non-cerebral lesion group compared to the cerebral lesion group. High-frequency rTMS of the primary motor cortex was appropriate for pain relief in intractable neuropathic pain, but low-frequency rTMS was not effective. Patients with pain caused by a non-cerebral lesion were suggested to be more suitable candidates for rTMS than those caused by a cerebral lesion.