Piriformis syndrome is an uncommon neuromuscular disorder that is caused when the piriformis muscle compresses the sciatic nerve. Piriformis Syndrome causes pain in the hip and buttock which radiates down the leg. This syndrome is often overlooked in clinical settings because its presentation may be similar to that of lumbar radiculopathy, primary sacral dysfunction, or innominate dysfunction.
The piriformis muscle is a flat, band-like muscle located in the buttocks near the top of the hip joint. This muscle is important in lower body movement because it stabilizes the hip joint and lifts and rotates the thigh away from the body. This enables us to walk, shift our weight from one foot to another, and maintain balance. It is also used in sports that involve lifting and rotating the thighs — in short, in almost every motion of the hips and legs.
The sciatic nerve is a thick and long nerve in the body. It passes alongside or goes through the piriformis muscle, goes down the back of the leg, and eventually branches off into smaller nerves that end in the feet.
Sciatic nerve compression can be caused by spasm of the piriformis muscle.
Piriformis syndrome usually starts with pain, tingling, or numbness in the buttocks.
Pain can be severe and extend down the length of the sciatic nerve (called sciatica). It often runs down the leg, like an electric shock, an ache, pins and needles. The reason it feels as if there’s a spasm in the buttock is because the piriformis muscle has knotted up and is actually in a spasm that can go on for days, months, and on occasion even years.
The pain is due to the piriformis muscle compressing the sciatic nerve, such as while sitting on a car seat or running. Pain may also be triggered while climbing stairs, applying firm pressure directly over the piriformis muscle, or sitting for long periods of time. Most cases of sciatica, however, are not due to piriformis syndrome.