Piriformis syndrome happens when the sciatic nerve becomes trapped as it runs through or under the piriformis muscle in the area of the buttocks. Symptoms of piriformis syndrome include pain, numbness, and tingling on the affected side. When diagnosing this condition, it is important to rule out other conditions since many disorders present with similar symptoms. In addition to a physical exam, a nerve conduction study is a useful tool in the diagnosis of piriformis syndrome.
Treatment of piriformis syndrome is largely non-operative and includes activity modification, a stretching regimen, pain medications, and physical therapy. Surgery may be considered if all conservative treatment fails. The surgical procedure includes piriformis tendon release and sciatic nerve decompression which both work to release the pressure placed on the sciatic nerve.
Piriformis syndrome results from trapping of the large nerve (sciatic nerve) running through the buttocks area by the piriformis muscle. The piriformis muscle lies deep within the buttocks area. It inserts onto the greater trochanter of the femur and originates on the front surface of the sacrum (figure 1). Risk factors for the development of piriformis syndrome include being born with a sciatic nerve that splits the piriformis, running through it instead of under it. Abnormal location of the sciatic nerve or a split in the nerve itself can also lead to piriformis syndrome. Additional risk factors are injury to the buttocks area, overuse of the piriformis muscle, and prolonged compression of the muscle such as with sitting for long periods of time.
Figure 1: Image showing the piriformis muscle in relation to the sciatic nerve
An individual suffering from piriformis syndrome will experience pain that radiates from the hip or buttocks area down to the back of the thigh and knee. They may also have pain with prolonged sitting or standing, muscle weakness in the affected leg, and numbness and tingling in the foot. Diagnosing piriformis syndrome can be difficult because many of the symptoms overlap with other disorders of the back, legs, and buttocks.
On physical exam, there may be tenderness when the area surrounding the piriformis muscle is touched. Additionally, pain, numbness, and/or tingling originating from the sacrum and radiating down the back of the leg are likely. When performing a special maneuver called the Frieberg test, which involves the doctor rotating the hip inwards while the patient is lying on their back, a person suffering from piriformis syndrome will often report pain.
Unlike most other conditions of the hip, x-ray is not useful since it is best used for visualizing bone, and piriformis syndrome involves muscles and nerves. In order to rule out other possible conditions, an MRI may be ordered. Ultimately, a nerve conduction study (EMG) is the most useful test for identifying If there is sciatic nerve compression and where it is occurring. This test involves measuring how fast the nerve sends impulses over a certain area of the body, and whether or not these impulses are normal, fast, slow, or absent.
When treating piriformis syndrome, non-operative management is the first line of defense. This includes modifying activities to avoid motions that make symptoms worse such as squatting and sitting for long periods of time. The doctor may also recommend at-home stretching exercises and physical therapy focused on strengthening the muscles that move the hip outwards (abduction). In addition to these exercises, pain medications such as NSAIDs and steroid injections into the piriformis muscle may help with managing symptoms of pain, numbness, and tingling.
Surgery is only recommended if all non-operative treatment fails to provide sufficient symptomatic relief. The surgery to treat piriformis syndrome involves piriformis tendon release and sciatic nerve decompression. Release of the piriformis tendon is when the tendon that attaches the piriformis muscle to the greater trochanter of the femur is cut to allow for increased movement of the muscle. This relieves any pressure that was placed on the sciatic nerve by the muscle. Sciatic nerve decompression includes locating the sciatic nerve where it runs through or under the piriformis muscle and cutting away the surrounding tissue in order to remove anything that will compress the nerve.
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Keywords: Piriformis syndrome, piriformis muscle, sciatica