Use of repetitive transcranial magnetic stimulation in pain relief

Repetitive transcranial magnetic stimulation (rTMS) of the cerebral cortex is a noninvasive strategy that could have the potential to relieve severe chronic pain, at least partially and transiently. The most studied target of stimulation is the precentral (motor) cortex, but other targets, such as the dorsolateral prefrontal cortex or the parietal cortex, could be of interest. Analgesic effects have been produced by rTMS in patients with neuropathic pain, fibromyalgia or visceral pain. Therapeutic applications of rTMS in pain syndromes are limited by the short duration of the induced effects, but prolonged pain relief can be obtained by performing rTMS sessions every day for several weeks. In patients who respond to rTMS but relapse, surgical implantation of epidural cortical electrodes and a pulse generator can be proposed to make clinical effects more permanent. The rate of improvement produced by rTMS may be predictive for the outcome of the implanted procedure. The place of rTMS as a therapeutic tool in the management of chronic pain remains to be determined.