A fully-implanted spinal cord stimulation system to restore sensation and relieve phantom limb pain after lower-limb amputation

About This Grant

In the United States, over 1.5 million people live with lower-limb amputation (LLA). Over 70% of people with LLA experience phantom limb pain (PLP), with 50% experiencing “high intensity” pain and 25% describing the pain as disabling. Opioid prescriptions among people with PLP are common, with one study showing nearly 30% of people that underwent an amputation exhibiting chronic opioid consumption. While scientific understanding of the mechanisms of PLP is limited, evidence suggests that the loss of sensory feedback after amputation contributes to development of PLP. There is growing evidence that neuroprostheses that restore somatosensation after amputation can reduce or completely alleviate PLP. For example, recent studies in our lab demonstrated that spinal cord stimulation (SCS) via percutaneously implanted leads can evoke sensations in the missing limb and reduce PLP. Widespread clinical adoption will require fully implanted systems that communicate wirelessly with external sensors on the prosthesis, allowing us to explore long-term at-home use of somatosensory neuroprostheses. The primary goal of this project is to quantify the safety and feasibility of a fully implanted SCS system to treat PLP by restoring sensation from the missing foot in people with LLA. Using a cross-over design, we will quantify changes in PLP while subjects with LLA use the system at home for 9 months, as compared to changes in PLP they experience with traditional SCS. Additionally, using cutting edge neuroimaging techniques, we will explore if there are changes in brain representations of the lower limb associated with PLP and whether those changes are reverted in subjects that experience pain relief via somatosensory restoration. UG3 Phase (Months 1-24) AIM 1: Obtain FDA and IRB approval for a study of sensory restoration to treat PLP in people with LLA We will perform biocompatibility and large-animal GLP studies in support of an IDE application for a one-year trial of a fully implanted SCS system to restore somatosensation and reduce PLP. AIM 2: Quantify changes in cortical representation of the lower limb in people with phantom limb pain We will perform magnetoencephalography studies in 10 people with LLA with PLP, 10 people with LLA without PLP, and 10 able-bodied controls to quantify changes in cortical representations that are associated with PLP. UH3 Phase (Months 25-60) AIM 3: Test safety and efficacy of somatosensory restoration for reducing phantom limb pain During a one-year implantation period, six subjects with LLA and PLP will progress through a randomized cross- over study in which they receive traditional, paresthesia-based SCS for six weeks and real-time somatosensory restoration for nine months, separated by a one-month washout period.