Piriformis syndrome remains a controversial due to the lack of specific tests for confirmation. The general principle behind the diagnosis is irritation of the sciatic nerve from the piriformis muscle in the hip and buttock. The piriformis muscle can irritate or compress the nerve as it passes under or travels though the muscle (Figure 1). The most common complaint from patients is buttock pain, combined with varying degrees of radiating pain in the distribution of the sciatic nerve. A generic term often used for this type of pain is “sciatica.” Piriformis syndrome can be considered as a possible cause of “sciatica,” sometimes referred to as “pseudosciatica.” Recently, the clinical symptoms of piriformis syndrome have been appreciated in the setting of hip impingement (FAI)[Link]. It is unclear, in this setting, if the symptoms are referred from the pathology associated with hip impingement or if impingement causes changes in the hip that lead to concomitant piriformis syndrome.
History & Exam
Patients’ complaints of buttocks pain are often exacerbated by specific functions of daily living and activities such as: squatting, sitting, climbing stairs, or lunges. Activity modification can help decrease symptoms, but patients generally have a rapid increase in symptoms when the offending activities are resumed. The piriformis muscle is important for external rotation (turning out) of the leg when it is straight and abduction (moving away) of the leg when it is flexed forward. The leg can be placed in positions to stretch the piriformis muscle and typically recreate the symptoms.
Diagnostic Tests and Imaging
Piriformis syndrome is a clinical diagnosis. This means that the diagnosis is based on history and physical exam. There are no specific tests, but X-rays, MRI, and nerve conduction studies are often completed to exclude other problems. If an MRI of this region is performed, it is Dr. King’s recommendation to perform an arthrogram of the hip. This special MRI places contrast dye in the hip joint which provides a more accurate evaluation of hip abnormalities such as cartilage injuries and labral tears.
The primary treatment for piriformis syndrome is non-operative. Physical therapy is geared toward progressive piriformis stretching, while avoiding offending activites. A steroid injection in the piriformis muscle may help decrease symptoms and complement physical therapy. Surgery remains an option if non-operative treatments fail, however, the results have been mixed. The surgical procedure involves a small posterior incision and release of the piriformis insertion into the greater trochanter.