The effect of a series of repetitive transcranial magnetic stimulations of the motor cortex on central pain after spinal cord injury

Objective: To study the analgesic effect of repetitive transcranial magnetic stimulation (rTMS) of the motor cortex on central pain in patients with chronic spinal cord injury (SCI). Design: Double-blind randomized controlled trial. Mean follow-up period was 4.5 weeks. Setting: General hospital. Participants: Twelve paraplegic patients due to thoracic SCI suffering chronic central pain (11 completed the study) who were randomly selected from a list of eligible patients. Intervention: Real or sham 10 daily motor rTMS treatments (500 trains at 5Hz for 10s; total of 500 pulses at intensity of 115% of motor threshold) using figure-of-8 coil over the vertex. Main Outcome Measures: Chronic pain intensity (visual analog scale [VAS], McGill Pain Questionnaire [MPQ]), pain threshold, and level of depression (Beck Depression Inventory). Results: Both real and sham TMS induced a similar, significant reduction in VAS scores (P<.001) immediately after each of the 10 treatment sessions and in VAS and MPQ scores after the end of the treatment series. However, only real rTMS conferred a significant increase in heat-pain threshold (4 degrees C, P<.05) by the end of the series. Most important, the reduction in MPQ scores in the real rTMS group continued during the follow-up period. Depression scores were equally reduced in both groups but similar to pain relief, depression continued to improve at follow-up in the real rTMS group. Conclusions: Whereas the pain alleviation induced by a single rTMS treatment is probably due to placebo, patients with SCI may benefit from a series of rTMS treatments.