Motor Cortex Stimulation for Neuropathic Pain: A Randomized Cross-over Trial.
BACKGROUND
Chronic motor cortex stimulation (MCS) has been used to treat medically refractory neuropathic pain over the past 20 years. We investigated this procedure using a prospective multicentre randomized blinded crossover trial.


METHODS
Twelve subjects with three different neuropathic pain syndromes had placement of MCS systems after which they were randomized to receive low ("subtherapeutic") or high ("therapeutic") stimulation for 12 weeks, followed by a crossover to the other treatment group for 12 weeks. The primary outcome measure was the pain visual analogue scale (VAS). Secondary outcome measures included McGill Pain Questionnaire (MPQ), Beck Depression Inventory-II, medication log, work status, global impression of change, and SF-36 quality of life scale.


RESULTS
The trial was halted early due to lack of efficacy. One subject withdrew early due to protocol violation and five subjects withdrew early due to transient adverse events. Six subjects with upper extremity pain completed the study. There was no significant change in VAS with low or high stimulation and no significant improvement in any of the outcome measures from low to high stimulation. SF-36 role physical and mental health scores were worse with high compared to low stimulation (p=0.024, p=0.005).


CONCLUSIONS
We failed to show that MCS is an effective treatment for refractory upper extremity neuropathic pain and suggest that previous studies may have been skewed by placebo effects, or ours by nocebo. We suggest that a healthy degree of skepticism is warranted when considering this invasive therapy for upper extremity pain syndromes.
1Department of Surgery (Neurosurgery),Dalhousie University,Halifax,Nova Scotia.
Julia A E
JA
Radic
2Department of Anaesthesia,Dalhousie University,Halifax,Nova Scotia.
Ian
I
Beauprie
1Department of Surgery (Neurosurgery),Dalhousie University,Halifax,Nova Scotia.
Paula
P
Chiasson
5Department of Clinical Neurosciences and Hotchkiss Brain Institute,University of Calgary,Calgary,Alberta,Canada.
Zelma H T
ZH
Kiss
1Department of Surgery (Neurosurgery),Dalhousie University,Halifax,Nova Scotia.
Robert M
RM
Brownstone
D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex; D009437:Neuralgia / Q000601:surgery* / Q000628:therapy*; D010147:Pain Measurement / Q000379:methods; D011446:Prospective Studies; D011788:Quality of Life; D016896:Treatment Outcome
Motor cortex stimulation; neuropathic pain