Understanding Piriformis Syndrome

Piriformis syndrome is essentially a compression of the sciatic nerve, which is the large nerve that runs from your buttock, originating from the lumbar spine nerve roots, which coalesce at the level of the mid-central buttock into the sciatic nerve, and then runs down the back of the thigh and into the lower extremity. Basically, it causes sciatica, which is a nerve pain that starts in the buttock and runs down the leg. Although not every single patient has that exact same presentation, the pain can be deep, gnawing, aching, intense, sometimes sharp, and stabbing, directly in the center of the buttock.

Causes And Symptoms of Piriformis Syndrome

Sometimes, patients who have piriformis syndrome prefer to stand as opposed to sit in a chair. They may have tripped, fallen, slipped on ice, and landed smack on the middle of the meat of the buttock cheek, causing a deep bruise to form, which we think could cause bleeding in the area, inflammation around the sciatic nerve in the piriformis, causing muscle spasms of that muscle. Then, that muscle, which has a very thick fibrous band in the middle of it, which is part of the tendon, can compress the nerve. Some people will have repetitive injuries such as runners or cyclists or athletes who do a lot of repetitive motion, which can cause irritation or tightening of the piriformis muscle itself as it travels over the sciatic nerve. At times, it may be related and may occur after a major operation on the hip, where there might be a manipulation of the hip or a fracture of the hip or a hip replacement where the muscles are taken down and reattached and it may be reattached slightly too tightly, and so you basically throw the balance off of what used to be normal to now something very tight crossing over a nerve that does not tolerate that very well.

The piriformis muscle is the muscle that travels directly over the sciatic nerve just as it exits the pelvis and into the buttock and thigh, and we believe that that is the main cause of compression of the sciatic nerve centrally in the buttock. Like I said previously, MR neurography can be helpful, though at times it's remarkably bland, meaning there's no obvious signs that we can find. We do look for swelling of the nerve, we look for flattening of the nerve, we look for changes in the fluid content of the nerve, we look for variable anatomy on the MRI, and we also look for rare tumors and things like that. Physical exam is important, the patient has to have a physical exam that's consistent with this disease process. We're looking for pain in the buttock, we're looking for pain over the sciatic nerve, we're looking for pain with exercises that will trigger the piriformis contracting.

Piriformis Treatment Options

Often, we prefer a near-total resection of the piriformis, removing essentially all of the visible piriformis from the sacral notch down to the hip. That's a well-tolerated procedure, it is an outpatient procedure. We have to sort of split the fibers of the gluteus maximus muscle, that's your buttock muscle, just split that, we hold that open through a retractor, it's done as an outpatient, we then remove this piece of muscle, unroofing the sciatic nerve, the inferior gluteal nerve, and the lumbar sacral plexus, making sure those are decompressed nicely, and then releasing those branches so that they can have more oxygen and take the pressure off.

Everyone recovers a little bit differently, but it's actually remarkably well-tolerated. Patients are expected to go home the next day from the surgical center or the outpatient hospital. They usually use ice for the first couple of days, we give them appropriate medications including over-the-counter medications, and occasionally they will need narcotics, not very often and not very much. Typically, patients are walking with the aid of a crutch or a cane immediately after surgery as a typical outcome, and it's remarkable actually how well patients are walking after surgery.

Eric H. Williams MD
Specializing in reconstructive surgery and pain relief in the Greater Baltimore area.