Posterior femoral cutaneous nerve impingement post marathon: A case report.

INTRODUCTION: Posterior femoral cutaneous nerve (PFCN) neuropathy is an uncommon, potentially under-recognized cause of low back, buttock, perineal, and posterior and lateral thigh pain and numbness. Most PFCN injuries are caused by intramuscular injections; however, this is the first reported case of a PFCN injury of hamstring pathology due to tendonitis caused by long-distance running.

CASE REPORT: A middle-aged man presented with right lower buttock pain, which started 2 weeks after running a marathon. The pain was located medial and superior to the ischia tuberosity and extended distally to the right scrotum with no testicular pain. The pain progressed such that he was unable to sit down for over a year. An initial MRI showed right hamstring tendonitis. Consults with sports medicine and hip orthopedics provided no clear diagnosis. He failed to improve with NSAIDs, physical therapy, massage, PRP injection, two Ganglion of Impar Nerve blocks, and trial of Pregabalin. The diagnosis was confirmed with temporary relief following a PFCN block. He was then advised to have the nerve resected because of the failure of nonsurgical treatment.

DISCUSSION: After excluding the more common etiologies of buttock pain and sitting intolerance, practitioners should consider the rarer condition of the impingement of the PFCN in runners.