Interventional neurophysiology for pain control: duration of pain relief following repetitive transcranial magnetic stimulation of the motor cortex.

The chronic electrical stimulation of a motor cortical area corresponding to a painful region of the body, by means of surgically-implanted epidural electrodes is a validated therapeutical strategy to control medication-resistant neurogenic pain. Repetitive transcranial magnetic stimulation (rTMS) permits to stimulate non-invasively and precisely the motor cortex. We applied a 20-min session of rTMS of the motor cortex at 10 Hz using a 'real' or a 'sham' coil in a series of 14 patients with intractable pain due to thalamic stroke or trigeminal neuropathy. We studied the effects of rTMS on pain level assessed on a 0-10 visual analogue scale from day 1 to day 12 following the rTMS session. A significant pain decrease was observed up to 8 days after the 'real' rTMS session. This study shows that a transient pain relief can be induced in patients suffering from chronic neurogenic pain during about the week that follows a 20-min session of 10 Hz-rTMS applied over the motor cortex.