The piriformis syndrome: a case report of an unusual cause of sciatica.

Notwithstanding the advent of magnetic resonance imaging (MRI), some etiologies of pyriformis syndrome continue to remain obscure and elude this investigation. We report a case characterized by a long hystory and a clinical picture both typical of pyriformis syndrome, caused by hypertrophy of the piriformis muscle clearly demonstrated at MRI. At surgery, we also found a likely neurovascular conflict not documented by MRI, consisting of an intimate relation between the sciatic nerve and the inferior gluteal artery. Following the surgical correction of both possible sources of pain, the patient experienced a slowly progressive relief of the sciatica.