The piriformis muscle which is located deep in the hip/pelvis, may become tight and/or inflamed, causing irritation to the sciatic nerve. Irritation to the nerve can lead to sciatica-like pain, tingling and numbness that may run from the hip down the leg and into the foot. Piriformis syndrome is only one of a number of possible causes of sciatica. The piriformis muscle is one of the small muscles deep in the buttocks whose primary function is to rotate the leg outwards. It runs from the sacrum (tailbone) and attaches to the femur (thigh bone). The sciatic nerve runs very close to this muscle and in approximately 10% of the population, it passes straight through the muscles itself. If the piriformis muscle becomes tight it can compress the sciatic nerve and elicit pain which can radiate down the leg. Piriformis syndrome occurs most frequently during the fourth and fifth decades of life and affects individuals of all occupations and activity levels. It is more common in women than men, possibly because of the biomechanics associated with the angle of the leg and pelvic anatomy. Reported incidence rates for piriformis syndrome among patients with low back pain vary from 5% to 36%.
Piriformis syndrome is most often caused by trauma to the gluteal muscles, causing muscle spasm and inflammation to soft tissue, resulting in nerve compression. Microtrauma may result from overuse of the piriformis muscle, such as in long-distance walking or running or by direct compression, such as a wallet in the back pocket. Another common cause of piriformis syndrome is tight adductor muscles on the inside of the thigh. When this happens, the abductors on the outside of the leg cannot work properly and compensate by putting more strain on the piriformis muscle.
The most common symptom of patients with piriformis syndrome is increasing pain after sitting for longer than 15 minutes. Many patients complain of pain over the piriformis muscle (ie, in the buttocks), especially over the muscle’s attachments at the hip. Symptoms, which may be of sudden or gradual onset, are usually associated with spasm of the piriformis muscle or compression of the sciatic nerve. Patients may complain of difficulty walking and pain with inward rotation of the leg. Some patients have a palpable mass in the gluteal’s caused by contraction of the piriformis muscle. A contracted piriformis muscle also cause outward rotation of the hip and leg so that when a patient is relaxed, laying on their back, the foot rotates outward — a feature referred to as a positive piriformis sign. Active efforts to bring the foot to midline result in pain.
A physical examination that incorporates regional orthopedic and neurological tests helps the doctor determine the source of the symptoms. In most cases the diagnosis is quite straight forward and there is no need for imaging such as x-ray, CT- or MRI. The diagnosis is made from the clinical tests. When neurological symptoms are present the doctor will do a full neurological examination in order to identify the cause of the symptoms. Once a specific and accurate diagnosis has been made the treatment can start.
As with all orthopedic problems rest and exercise modification is important to ensure a quick recovery. The chiropractic treatment is aimed at restoring the function of the pelvic and spinal joints, which is often the cause. A pronated foot (fallen arch) may cause rotation of the leg, which can put extra strain on the muscle, this is also addressed through foot orthotics and specific exercises for the feet. Trigger point therapy, massage, stretching and strengthening exercises are also a part of the treatment plan. Postural and ergonomic advice is beneficial to help prevent future problems. Inactive and weak gluteal muscles can also be a predisposing factor of the syndrome.