[The piriformis syndrome: a rare cause of non discogenic sciatica. A case report].

Atypical sciatic pain without apparent discogenic origin should raise the possibility of a non-discogenic etiology, especially tumoral but also infectious or inflammatory. We report the case of a young patient presenting with non-discogenic S1 radiculopathy due to sciatic nerve involvement in the subpiriformis canal secondary to piriformis muscle inflammation. The authors review technical considerations and results of MRI which is of great value in the evaluation of piriformis muscle pathology.