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 5 Hz for 10 s; 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.