Piriformis Syndrome

Introduction and prevalence

Piriformis Syndrome is an overlooked cause of buttock and sciatic pain. Some studies estimate the prevalence of piriformis Syndrome to be around 17% among low back pain patients.

Etiology and Pathophysiology

The Piriformis Syndrome occurs when the piriformis muscle compresses the sciatic nerve at the level of the ischial tuberosity. The causes include injury, piriformis muscle hypertrophy, prolonged sitting, repetitive motions such as long-distance running and climbing stairs, and muscle tightness. Other causes of sciatic nerve entrapment include space-occupying lesions in the deep gluteal space.

Clinical presentation

Patients often report pain in the gluteal region down the back of the leg with numbness in the buttocks and tingling sensations along the distribution of the sciatic nerve. These symptoms may be increased by rotation of the hip in flexion or knee extension, along with tenderness over sciatic notch, and atrophy of gluteus maximus.

Physical examination

The most validated tests for Piriformis syndrome the FAIR test, Beatty maneuver, Freiberg test, and the Pace test.

  • The FAIR test comprises of the patient lying on the unaffected side with their hip flexed, and having the examiner adduct their leg and internally rotate their hip, with pain in the gluteal area suggesting the Piriformis Syndrome and pain in the groin suggesting labral tear.

  • The Beatty maneuver is when the patient lies on the unaffected side with the hips and knees in slight flexion; when the patient lifts the affected leg up away from the examination table, then pain in the buttock can be suggestive of Piriformis Syndrome.

  • In Freiberg test, the patient is supine with their knees extended and the examiner passively rotates the hip internally, with buttock and radicular pain suggestive of Piriformis Syndrome.

  • In the Pace maneuver the patient abducts the legs in the seated position, and pain in the buttock area is suggestive of the Piriformis Syndrome.

Investigations

Clinicians should rule out facet arthropathy, herniated nucleus pulposus, lumbar muscle strain, and spinal stenosis. If there is still clinical suspicion despite a thorough history and physical 12 examination, Ultrasound, MRI, CT, and EMG can be used to exclude other conditions and support clinical decision making.

Management

The current management options include analgesics, NSAIDs, muscle relaxants, physical therapy, steroid injections, trigger point injections, botulinum toxin injections, and surgery. The management strategy starts with conservative measures, including analgesics, NSAIDs, and nerve stretching exercises. Some helpful exercises include knees to chest, Cobra (yoga pose), seated hip stretch, standing hamstring stretch, and seated spinal twist. Evidence for muscle relaxants are limited. Injections have been shown to be very helpful for treating Piriformis Syndrome that does not respond to conservative measures. A combination of anesthetic and steroid is injected into and around the muscle with the use of US or x-ray guidance in order to numb the area and decrease the inflammation and swelling. The use of Botox injections in patients with Piriformis Syndrome has also been shown to be very beneficial. Surgery is not recommended for Piriformis Syndrome, however, as a last resort, the surgeon can decompress the nerve if there is any impingement or lyse any adhesions or scars from the nerve.