The pyriformis syndrome: review and case presentation.

The pyriformis syndrome is a rare entrapment neuropathy in which the sciatic nerve is compromised by the pyriformis muscle or other local structures. It usually presents with sciatic pain and hypoaesthesia and a limp caused by weakness of the gluteus maximus muscle. Peroneal nerve innervated muscles and hamstrings are also usually affected. The diagnosis relies on the clinical presentation and the EMG findings. Other causes of symptoms should be excluded by careful examination, detailed x-ray studies of the lumbosacral spine (including myelogram), sacro-iliac and hip joints. A case of this syndrome occurring in a previously healthy 42 year old woman and her follow-up investigations are reported.