This is an interesting disorder that is one cause of sciatica, other than a herniated disc in the low back. The sciatic nerve is compressed by the piriformis muscle causing an irritation of the sciatic nerve with numbness in the buttocks running down the lower thigh into the leg. When someone has these symptoms the biggest thing to rule out is a herniated disc of the spine. So, if there is sciatica but no clear spinal signs, think piriformis muscle inflammation.
What causes it? In approximately 17% of the population the sciatic nerve passes through the piriformis muscle rather than underneath it. This is the supposed cause of this syndrome (non-disc related sciatica). Also anatomically, weak gluteal (buttock) muscles, which may occur with a lot of desk type jobs that involve much sitting( hip flexion with accompanying shortening and tightening of the hip flexors). With weak gluts, other muscles have to compensate such as the hamstrings, adductor muscles( inner muscles of the thighs), and the piriformis. This results is hypertrophy of the piriformis with the resultant syndrome.
Other causes could include overuse injury such as strenuous use of the legs( anyone do the STP bike ride lately?) such as biking or rowing. Also, runners, who engage in forward type of activities as well, are susceptible to developing this syndrome. So, it is important to perform lateral (side) type of stretching to balance out the legs. If not properly stretched, the legs can develop overly tight adductors and out of proportion weak abductors. The piriformis muscle becomes large and sciatic nerve impingement is inevitable. The key is to keep the outside muscles of the hip, called abductors in proper stretch to take the strain off of the piriformis.
Interestingly, not only does the spasm of the piriformis cause sciatic nerve symptoms but the pudental nerve may also be irritated. This nerve controls the muscles of the bowel and bladder. The syndrome may present with loss of bowel and urine function as well as saddle anesthesia( numbness around the anus).
Some other potential causes of the syndrome include a falling injury, tight SI joints( sacro-iliac, or low back joints), over pronation of the foot, or sitting on a wallet.
How is it diagnosed? Diagnosis is largely clinical, i.e. there not really any good or reliable imaging tests for this syndrome. Presentation includes pain in the buttock, back of the thigh and lower leg made worse with prolonged sitting, activity or walking.
What is treatment? Treatment is conservative including avoiding such activities as running, biking or rowing for a while. Also, muscle relaxants , anti-inflammatories as well as physical therapy or massage to stretch and strengthen. If these do not work, see your doctor to consider an imaging study to rule out other pathology. Treatment for weak abductors and tight adductors include stretching and strengthening of these muscles. It is possible to see results after just a few days.
the piriformis stretch
Dr. Frank Marinkovich owns and operates Eastside Family Health Center in Kirkland, WA. Serving Kirkland and the Eastside, Seattle, Bellevue, Renton and the surrounding local communities. Specializing in Primary Care, Automobile Accidents and FAA physicals. Visit them online at Eastside Family Health Center or call them at (425) 899-2525.
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