Piriformis Syndrome

Sciatica is characterized by radiating nerve pain extending from the back of the hip down the leg towards the outer side of the ankle. Approximately 95% of sciatica is due to nerve root irritation in the lumbar spine. This can occur in people who do not even have much accompanying back pain.

Less frequently, sciatica can originate outside of the lumbar spine. For these cases, the piriformis muscle may be the culprit. The piriformis is a small muscle that exits through a notch in the back of the pelvis along with the sciatic nerve. The nerve passes underneath the muscle and courses down the back of the leg while the piriformis crosses over to attach on the back of the hip. Either from trauma or overuse problems, the muscle can compress the sciatic nerve and characteristically cause pain in the back of the hip as well as radiating sciatica symptoms.

Regardless of whether sciatica is coming from the back or the less common piriformis, most of these problems will respond to a generalized conservative program. This includes trying to identify and modify any offending activities as well as supervised physical therapy and non-steroidal anti-inflammatory medications. Treatment by a knowledgeable physical therapist often can help alleviate the symptoms and may also help to clarify the diagnosis. Recalcitrant sciatica usually obligates a more extensive investigation of the lumbar spine, sometimes including an MRI. If piriformis syndrome is suspected, this can be substantiated by palpation of the piriformis over the sciatic nerve as it exits from inside the pelvis. An injection of the piriformis muscle may be therapeutic as well as diagnostic, localizing the piriformis as the source of symptoms. When needed, this injection can be performed in the office with ultrasound guidance.

Surgical release of the piriformis and decompression of the sciatic nerve can be successful for recalcitrant cases, but is rarely necessary. There are numerous anomalies where the nerve may pass through or around portions of the piriformis muscle. Thus, if the piriformis muscle is released, this entire area must be carefully explored, to assure adequate decompression of the sciatic nerve. The results of release are often remarkable with regard to pain relief and patient satisfaction, but this is not always the case. This reflects some of the difficulties with this diagnosis even with the most thorough clinical evaluation. We have experienced no complications with this procedure, but there are always potential risks associated with open surgery in this area.