The piriformis muscle is located in the buttocks and extends from the base of the spine to the thigh; it helps to rotate the hip, leg, and foot. Piriformis pain syndrome causes spasms and pain in the area and can also irritate the nearby sciatic nerve, leading to more pain, numbness, and tingling along the back of the leg and into the foot. Often, the pain is confused as being related to hamstring straining. It is usually caused by overuse of the muscle from excessive exercise or over-stretching, which leads to spasms; other symptoms are tightening or tingling of the muscle due to injury or spasm, bleeding in the piriformis muscle, injury such as a fall or auto accident, a sedentary lifestyle, or muscle tension and excess weight due to pregnancy.
The most commonly reported symptoms are acute tenderness in the buttock and sciatica-like pain down the back of the thigh, calf, and foot. Other symptoms can include a dull ache in the buttocks, pain when walking up the stairs or inclines, increased pain after prolonged sitting, and a reduced range of motion at the hip joint.
The doctor will take a medical history and perform a physical exam to diagnose piriformis pain syndrome. Diagnostic tests like X-rays, magnetic resonance imaging (MRI), and nerve conduction tests may be recommended. The FAIR test (flexion, adduction, and internal rotation) can be used to measure delays in sciatic nerve due to compression from the piriformis.
Stretching and physical therapy may improve this condition. Piriformis injections, which are administered directly into the muscle to decrease spasms and pain, or onabotulinumtoxinA (or Botox), which relaxes the muscle and reduces pressure on the sciatic nerve, may also be recommended. The application of electrical stimulation to the buttocks with transcutaneous electrical nerve stimulation or interferential current stimulator can help to block pain and reduce muscle spasms related to piriformis syndrome.