(Kiosk 1) Piriformis Syndrome Causing Lumbosacral Plexopathy Following a Fall: A Case Report

Case Diagnosis: 38-year-old female with left lower extremity (LLE) neuropathic pain and weakness

Case Description or Program Description: Patient was hospitalized following a fall from her bike which caused left foot drop, LLE swelling, weakness, and neuropathic pain. She was diagnosed with complex regional pain syndrome and was referred for electromyography and nerve conduction studies (EMG/NCS) to evaluate the left foot drop. EMG/NCS revealed a left-sided lumbosacral plexopathy at or above the levels of the superior/inferior gluteal nerves, with involvement of both the superior and inferior gluteal nerves and sciatic nerve.

Setting: Outpatient electromyography clinic

Assessment/Results: EMG/NCS showed absent left tibial and peroneal motor and sural sensory responses. EMG showed left-sided lumbosacral plexopathy at the level of the superior/inferior gluteal nerves with involvement of the sciatic nerve in addition to the superior and inferior gluteal nerves. Review of the MRI imaging of the lumbar plexus on the left was indicative of enlargement of the left sciatic nerve adjacent to an enlarged left piriformis muscle as well as atrophy of the gluteal muscles. Given this, in conjunction with the EMG/NCS findings, the cause of the lumbosacral plexopathy were likely related to entrapment due to inflammation and enlargement of the piriformis following her fall.

Discussion (relevance): Piriformis syndrome is largely a diagnosis of exclusion and a difficult clinical diagnosis to make given its similar presentation to a variety of other neuropathies. MRI is a useful imaging modality that can help to exclude other causes, or as in the case presented, demonstrate an interaction between the piriformis and the lumbosacral plexus.

Conclusions: While uncommon, piriformis syndrome can cause lumbosacral plexopathy following a traumatic event such as a fall.