Abstract
OBJECTIVE: Previous studies demonstrated the efficacy of Intramuscular Nerve (IMN) therapy with a 4-lead percutaneous, peripheral nerve stimulation (PNS) system in reducing hemiplegic shoulder pain (HSP). This case series investigates the feasibility of a less complex, single-lead approach in reducing HSP. METHODS: Eight participants received one percutaneous intramuscular lead in the hemiparetic deltoid muscle and were then treated 6 hours/day for 3 weeks. The primary outcome measure was the Brief Pain Inventory (Short-Form) Question 3 (BPI3), which queries worst pain in the last week on a 0 to 10 numeric rating scale. Secondary outcomes included pain interference (BPI9) and Medical Outcomes Study Short-Form 36 (SF-36v2). Primary and secondary outcomes were assessed at the end of treatment (EOT) and 1 and 4 weeks after the EOT. RESULTS: All participants tolerated the treatment well with 96% compliance. All leads remained infection-free and were removed intact at the EOT. On average, participants exhibited 70% reduction in BPI3 at the EOT and 61% reduction at 4 weeks after the EOT. All participants satisfied the success criterion of at least a 2-point reduction in BPI3 at the EOT. Longitudinal analysis revealed significant treatment effect for BPI3 (F = 14.0, P < 0.001), BPI9 (F = 5.9, P < 0.01), and the bodily pain domain of SF-36v2 (F = 12.8, P < 0.001). CONCLUSION: This case series demonstrates the feasibility of a single-lead, 3-week IMN therapy for the treatment of chronic HSP. Additional studies are needed to further demonstrate safety, efficacy, and long-term benefit, define optimal prescriptive parameters and dose, and expand clinical indications.