Piriformis syndrome is a condition that is believed to occur as the result of pressure or irritation of the sciatic nerve by the piriformis muscle.
The piriformis muscle is a bilateral muscle that is located on each side of the buttocks. It arises from the front of the sacrum and traverses laterally to attach to the greater trochanter of the femur.
The function of this muscle is to abduct the thigh. It also externally rotates the thigh at the thip joint. (Abduction refers to the action of moving the thigh in a lateral or outside direction)
The sciatic nerve either passes under or, in about 17% of the population, through the piriformis muscle.
Many believe it is because the nerve can pass through the piriformis muscle that this predisposes the nerve to abnormal compression when the muscle overly contracts, is in spasm or there exists another muscular imbalances in the opposing or antagonistic muscle(s).
However, in one study it was found that in a group undergoing surgery due to unresponsive treatment for what was believed to be piriformis syndrome still only exhibited a 17% incidence of the nerve passing through the muscle.
A possible explanation for this painful syndrome may be that the sciatic nerve is already irritated and the contracted piriformis is only the" last straw" in the cause of sciatica. This may explain why in many cases despite the efforts to relax the piriformis muscle, thereby reducing the pressure, the sciatic symptoms still persist to some degree.
I believe, in most cases of lower back pain, the cause is often multifactorial and the treatment approach should be so as well. Most clinicians address only minimal possible associated causes or contributing factors and that explains why it will often remain a chronic or recurrent condition.
All structural and functional aberrations and conditions must be fully addressed to assure a more permanent solution to a piriformis syndrome. Failure to correct, manage, or minimize any associated contributing factors will most likely be met with incomplete success in the outcome.
The symptoms are the same as the symptoms of any irritation or compression to the sciatic nerve.
Any of the following symptoms may exists:
There are no diagnostic test to determine piriformis syndrome. The diagnosis is based on the patient's history, clinical presentation, and supported by orthopedic testing along with eliminating other possible causes of the sciatica. When no other condition is found that could be the cause of the sciatica then a diagnosis of piriformis syndrome is rendered.
However, one should use caution. Often times, when a herniated (bulging) disc is identified on MRI in the presence of sciatica it should not be assumed that the disc is the cause of the sciatic. It may be the herniated disc exist without causing any true or significant compression of the sciatic nerve and is therefore just an incidental finding.
In addition to the symptoms, an exam can reveal shortness or tightness of the piriformis, point tenderness, weakness, or pain upon stretching or contracting the piriformis muscle.
In the absence of other possible conditions and positive exam findings as mentioned above, along with presenting symptoms and a history that suggests some type of trauma or irritation of the piriformis muscle, it is probably safe to assume a piriformis syndrome diagnosis.
As in all cases of lower back pain, a piriformis syndrome must be treated by properly and adequately identifying, minimizing, managing or correcting all structural and functional deficits and conditions as they relate to the overall structure and function of the neuro-muscular and skeletal systems.
The more common associated conditions are: