The investigators plan to 1. verify that spinal cord stimulation increases hip muscle strength in subjects with SMA, 2. verify that spinal cord stimulation improves motor control in subjects with SMA, 3. verify that spinal cord stimulation induces measurable changes in spinal circuits and motoneuron recruitment properties in the 29 day course of implantation.
Spinal cord stimulation (SCS) has shown remarkable efficacy in restoring motor function in people with spinal cord injury by recruiting afferent input to enhance the responsiveness of spared neural circuits to residual cortical inputs. This pilot will test if SCS can show evidence to improve motor deficits in people with type 3 or 4 spinal muscular atrophy (SMA). The investigators will enroll up to six subjects with Type 3 or 4 SMA aged 16 or older that show quantifiable motor deficits of the legs but are able to stand independently. The investigators will then implant the subjects with percutaneous, bilateral, linear spinal leads near the lumbar spinal cord for a period of up to 29 days. Although these leads are not optimized for motor function but rather for their clinically approved indication of treating pain, the investigators believe they provide a safe technology enabling our team to perform scientific measurement necessary to evaluate potential for effects of SCS in motor paralysis with SMA. After the end of the study, the leads will be explanted.