Piriformis synrome is a neuromuscular disorder that occurs when the sciatic nerve is compressed or otherwise irritated by the piriformis muscle. This causes pain, tingling and numbness in the buttocks and along the course of the sciatic nerve. The syndrome may result from anatomical variations in the muscle-nerve relationship, or from overuse or strain. Recent uncontrolled studies advanced theories behind the disorder. However, following a large scale formal prospective outcome trial using Class A study design as outlined by the American College of Physicians, the weight of the evidence based medicine is that piriformis syndrome should be considered as a possible diagnosis when sciatica occurs without a clear spinal cause