Spinal cord stimulation for lower limb ischemic pain treatment.

OBJECTIVES: Spinal cord stimulation (SCS) was proposed many years ago for pain treatment but healing of ischemic ulcers opened a new treatment indication. The aim of this review was to assess the efficacy of SCS.
METHODS: studies regarding ischemic pain, limb ischemia and SCS reported on Pubmed have been reviewed, including randomized controlled trials (RCTs), clinical trials, Cochrane library review, neurophysiological studies and microcirculatory evaluations.
RESULTS: Five RCTs, three multicenter studies and many clinical trials and reports of series have documented the clinical efficacy of SCS in the treatment of ischemic pain, particularly in patients with post-implantation increased blood flow. Pain relief, ulcer healing and limb salvage seems to be greater in non-diabetic patients, in diabetic without autonomic neuropathy, and in patients with rest pain or ulcer more than in patients with gangrene. A pain reduction of 75% was reported in the 3 RCTs; pain relief was significantly greater than in control group. Another study reported a lower use of analgesic in the SCS group. Moreover, pain relief obtained with SCS is maintained at follow-up while relief after medical treatment disappears quickly. The three multicenter studies showed a total pain relief between 41% and 43% and a cumulative pain reduction of 75% in 64.8% of cases. The clinical trials reported a pain reduction in up to 91% of patients. Based on six studies, the Cochrane reviewers found evidence to favor SCS over standard conservative treatment to improve limb salvage and clinical situation in patients with non-reconstructable critical limb ischemia (CLI). The mechanism of action of SCS is not completely clarified. DISCUSSION AND
CONCLUSIONS: the endovascular approach reduced the number of patients unsuitable for revascularization, however, some patients cannot be treated by angioplasty or open surgery; moreover, some are unfit for surgery, and others have persistent distal ischemia and pain with a functioning revascularization. In these cases SCS (alone or associated with prostanoids) can be indicated on the basis of the more recent evidences. A trial period with external stimulator, associated with a microcirculatory evaluation, is currently utilized to select patients that can derive benefit from this treatment, reducing costs.