Piriformis Syndrome · What Is It, Causes, Diagnosis, and More

Piriformis syndrome is a painful musculoskeletal condition of the lower back that occurs when the piriformis muscle spasms or the sciatic nerve is impinged by prolonged or excessive contraction of the piriformis muscle, leading to the buttock and hip pain. The piriformis muscle assists in rotating the hip from side to side and turning the leg and foot outward. The piriformis muscle is located deep in the buttock, originating at the lower end of the spine. It then runs diagonally through the greater sciatic notch to insert on the upper surface of each femur. The greater sciatic notch contains the sacroiliac joint (SI joint or SIJ) at the superior margin and functions as an opening for the sciatic nerve to travel to the leg, generally underneath the piriformis muscle. Some individuals may have the sciatic nerve running directly through the piriformis muscle.

While the exact cause of piriformis syndrome remains unknown, the suspected mechanism postulates that it occurs due to the proximity of the piriformis muscle to the adjacent sciatic nerve. The piriformis muscle spasms can exert pressure on or irritate the sciatic nerve, leading to piriformis syndrome. Other contributing causes of piriformis syndrome can be categorized under primary and secondary piriformis syndrome.

Primary piriformis syndrome is quite rare and is caused by the presence of an underlying anatomical cause, such as atypical development or location of the piriformis muscle or sciatic nerve; unusual spinal alignment; split sciatic nerve, in which part of the sciatic nerve passes through or over the piriformis muscle; and anomalous sciatic nerve pathways.

Symptoms of piriformis syndrome include persistent lower back and gluteal pain, pain with increased piriformis muscle tenderness, and groin pain. Gluteal pain may be chronic, radiate to the distal part of the lower extremities, and worsen with squatting or walking. Sciatica-like pain is a common symptom of piriformis syndrome, in which individuals present with “shooting” or “electric-like” nerve pains radiating from the lower back or buttock down the back of one leg into the thigh, calf, and foot. An individual may also experience symptoms of pain, tingling, and numbness. Additional symptoms may include external tenderness near the greater sciatic notch, labia majora or scrotal pain, dyspareunia in women, and disturbances of potency in men.

Depending on the individual, symptoms of piriformis syndrome may be aggravated after prolonged sitting, walking, running, or exercise and may improve upon lying down, bending the knee, or walking. Individuals with piriformis syndrome have difficulty walking, sitting, or passing bowel movements. In some cases, the pain may be severe enough to prevent everyday tasks such as driving or performing household chores.

Diagnosis of piriformis syndrome is typically made after a thorough review of symptoms and medical history, followed by a  physical exam. Piriformis syndrome is often diagnosed after ruling out other possible conditions that may be causing an individual’s symptoms, such as lumbar disc herniation or sacroiliac joint dysfunction. Therefore, piriformis syndrome is a diagnosis of exclusion.

Certain tests are conducted to pinpoint specific signs, symptoms, and motions that exacerbate pain. Examples of diagnostic tests include SI joint palpation, straight leg raise, and hip rotation in a sitting or supine position.

While there is no specific laboratory test, radiographic study, or biopsy that may confirm a diagnosis of piriformis syndrome, a medical professional may request specific imaging such as a plain film x-ray, magnetic resonance imaging (MRI), computed tomography (CT) scan or musculoskeletal ultrasound to rule out other causes of pain, such as arthritis or lumbar disc herniation. Electromyography, which is a procedure that assesses the health of muscles and the nerve cells that control them, may also be conducted to differentiate piriformis syndrome from other possible disorders, such as nerve impingement. 

Treatment of piriformis syndrome involves a variety of non-pharmacological and pharmacological measures, depending on an individual’s severity of symptoms, quality of life, and chronicity of the condition.

Conservative treatment options for treating piriformis syndrome typically involve rest, heat, and ice therapy to the affected area(s), deep massage, and physical therapy. Physical therapy interventions commonly involve gait adjustment, sacroiliac joint mobilization, soft tissue mobilization, and range of motion exercises (e.g., stretching the piriformis muscle and strengthening hip muscles). In some cases, acupuncture, psychotherapy, and transcutaneous electrical nerve stimulator (TENS) treatment may also be considered. TENS is a handheld device that sends small electrical charges through the skin into the nerves to interfere with pain signals from the brain, thereby reducing pain. Visiting an osteopathic physician (DO) that can perform the osteopathic manipulative treatment (OMT), which involves removing as much tension from the piriformis muscle as possible, reducing pain, and restoring a normal range of motion, is also an effective treatment option.

In cases where conservative treatment options do not provide optimal relief, short-term pharmacological treatment may be considered. Pharmacological treatment options include non-steroidal anti-inflammatory medications, such as naproxen or ibuprofen, to reduce swelling and inflammation; muscle relaxants, such as cyclobenzaprine; antispasmodics, such as baclofen; and neuropathic pain medications, such as pregabalin. Local anesthetic injections, botulinum toxin, or a corticosteroid agent may be considered to provide diagnostic and therapeutic benefits.