Refractory sciatica due to unilateral piriformis hypertrophy: a case report highlighting an extraspinal pain generator
Mustafa A Hammad1, Wasef Alhroub1, Ahmad M Isaid1
1American NeuroSpine Center, American NeuRegenix Institue, Department of Neurology and Regenerative Medicine, Ramallah and Stockbridge, Palestine.
Introduction:
Piriformis syndrome is an uncommon and frequently under-recognized cause of extraspinal sciatica that results from irritation or compression of the sciatic nerve within the deep gluteal space. Because its clinical manifestations often overlap with those of lumbosacral radiculopathy, diagnosis is challenging, particularly when conventional lumbar imaging is unrevealing. Structural piriformis hypertrophy is a rare and poorly characterized cause of chronic sciatic pain.
Case Presentation:
A 42-year-old man had severe left-sided sciatica and mild chronic low back pain for 4 years despite multiple treatments, including epidural injections, nerve blocks, medications, and platelet-rich plasma therapy. Lumbar, brain, and whole-spine MRIs showed no significant abnormalities, and electrodiagnostic testing revealed chronic unilateral neurogenic changes without clear localization. Pelvic MRI later demonstrated marked hypertrophy of the left piriformis muscle with deep gluteal asymmetry and no other intrapelvic lesion, supporting a diagnosis of probable piriformis-related extraspinal sciatica.
Discussion:
This case highlights the diagnostic complexity of piriformis syndrome and the importance of considering extraspinal causes in patients with persistent sciatica despite nondiagnostic lumbar imaging and unsuccessful spine-directed interventions. Pelvic MRI identified a plausible structural pain generator, while electrodiagnostic testing helped exclude alternative neurological disorders. Together, these findings emphasize the value of integrating clinical assessment with targeted imaging and neurophysiological evaluation.
Conclusion:
Piriformis hypertrophy should be included in the differential diagnosis of refractory sciatica when spinal investigations fail to explain symptom severity. Early use of targeted pelvic imaging may facilitate diagnosis, reduce unnecessary spinal interventions, and improve management of patients with chronic extraspinal sciatica.