Ultrasound-Guided Single-Incision Axillary Nerve PNS Implant for Chronic Shoulder Causalgia After Humerus Fracture and ORIF: A Case Study

Case Diagnosis: A 72-year-old male with chronic right shoulder pain following open reduction internal fixation for a left humerus fracture.

Case Description or Program Description: Despite undergoing physical therapy, corticosteroid injections, and surgery, the patient experienced persistent pain. A temporary percutaneous peripheral nerve stimulation (PNS) implant targeting the left suprascapular nerve for 60 days provided minimal relief (10%). A subsequent 60-day percutaneous axillary nerve PNS led to a 70% improvement. One month post-explant, the pain returned, prompting the need for a permanent left axillary PNS implantation using a single-incision, ultrasound-guided technique under local anesthesia.

Setting: Outpatient interventional pain clinic.

Assessment/Results: After axillary PNS implantation, the patient reported 90% pain relief, improved sleep, and increased shoulder mobility, allowing him to perform daily activities with minimal discomfort. At the six-month follow-up, pain relief remained stable, significantly enhancing his quality of life.

Discussion (relevance): Chronic post-surgical shoulder pain from nerve injury and causalgia presents significant management challenges. Neuromodulation provides a targeted approach by modulating specific nerve pathways, with PNS proving effective in treating causalgia and neuropathic pain. Despite the advancements in neuromodulation, addressing post-surgical pain syndrome in the upper extremities continues to be difficult. While spinal cord stimulation (SCS) and dorsal root ganglion (DRG) stimulation are utilized for neuropathic pain, their effectiveness for shoulder pain is limited. The ultrasound-guided, single-incision technique minimizes recovery time and enables immediate post-implant utilization, facilitating early pain relief. This case underscores PNS as a potential long-term solution for shoulder pain in patients who have exhausted conventional treatments.

Conclusions: PNS may be an effective, non-invasive treatment for shoulder causalgia, offering sustained pain relief and functional improvement when conservative therapies fail. Larger studies with expanded patient populations are needed to further assess its effectiveness.