Treatment of post-amputation pain with peripheral nerve stimulation

Background Present treatment methods are often unsatisfactory in reducing post-amputation pain. Peripheral nerve stimulation (PNS) could reduce the pain, but it is rarely used because present methods require invasive surgical access and precise placement of the leads in close proximity (≤2 mm) with the nerve. Methods The present study investigated the feasibility of delivering PNS to patients with moderate-to-severe post-amputation pain in the lower extremity using a fine-wire lead placed percutaneously under ultrasound guidance a remote distance (0.5-3.0 cm) away from the sciatic and/or femoral nerves. Results Fourteen of the 16 subjects who completed in-clinic testing responded to stimulation, reported ≥75% paresthesia coverage, obtained clinically significant pain relief, and proceeded to a two-week home trial with a percutaneous PNS system. Two of the 14 responders had their leads removed early because of accidental dislodgement (N = 2), two had temporary discomfort near the lead (N = 2), and one had return of post-amputation pain despite stimulation (N = 1) and did not complete the home trial. The nine responders who completed the home trial reported reductions in their mean daily worst post-amputation pain (56 ± 26%, 56 ± 26%, N = 9), average residual limb pain (72 ± 28%, 42 ± 27%, N = 7), average phantom limb pain (81 ± 28%, 47 ± 48%, N = 7), residual limb pain interference (81 ± 27%, 53 ± 17%, N = 6), phantom limb pain interference (83 ± 31%, 56 ± 46%, N = 7), and Pain Disability Index (70 ± 38%, 55 ± 32%, N = 9) during the second week of stimulation and four weeks after the end of stimulation, respectively. All nine responders rated their change in quality of life as improved at the end of stimulation and at the end of the four-week follow-up period. Subjects reported minor decreases in the Beck Depression Inventory scores (43 ± 51%, 32 ± 57%, N = 9). Most subjects had no substantial changes other than minor decreases (N = 3) in pain medication. Conclusion Achievement of significant pain relief and improvements in quality of life with a minimally invasive method of PNS holds promise for providing relief of post-amputation pain.