Piriformis Syndrome Overview
The piriformis muscle is a very small muscle located in the buttocks region and is found in close approximation to the sciatic nerve. Years ago, cadaver dissections revealed the close approximation of the sciatic nerve and the piriformis muscle. Clinicians at that time did not have the knowledge that leg pain originates from spinal nerve compression caused by bone spurs and disc herniations in the spinal canal.
70 years ago, it made sense for clinicians to draw the conclusion that the piriformis muscle could compress the sciatic nerve. During dissection of cadavers, the clinicians found that 3-5% of sciatic nerves were found to travel directly through this muscle and about 1-2% of the general population developed leg pain.
Fortunately, the discoveries of nerve compression in the spine in the twentieth century by Mixter and Barr dispelled the notion that piriformis syndrome is the cause of sciatica. Unfortunately, piriformis syndrome became so popular that this diagnosis still continues as a diagnosis of leg pain to this day. This is due to two separate associations.
First, the onset of sciatic nerve pain due to spinal nerve compression starts in the buttocks right around the piriformis muscle. This association of the location of the sciatic nerve and the onset of local pain is tempting to then blame the unfortunate piriformis muscle as the cause of this nerve pain.
The other unfortunate association is that tenderness (using fingers to palpate this region) around the piriformis muscle will also elicit pain down the nerve. This is due to the fact that compression of the nerve in the spine due to disc herniation will make the entire nerve sensitive in certain individuals. This sensitivity can be found not only in the region of the piriformis muscle but also in the back of the knee. The close approximation of this tenderness and sciatica makes certain clinicians accept the diagnosis of piriformis syndrome to this day.
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(Please keep reading below for more information on this condition.)
The “Cure” and Diagnosis of Piriformis Syndrome
The “cure” for piriformis syndrome is to find the cause of the nerve pain. This typically will be a good physical examination and identification of the spinal nerve root responsible for the radiation of pain. X-rays and MRI evaluations are part of the diagnostic testing. Finally, if there is any doubt of the origin of pain, a selective nerve root block (see website) can be diagnostic.
Does piriformis syndrome really exist? The answer is yes but it is an extremely rare condition. In 30 years of practice, I have seen this syndrome twice. If every other cause of nerve pain has been ruled out and the only potential cause left is piriformis syndrome, then this diagnosis can be looked into.
The diagnosis is made by again by first ruling out every other type of nerve disorder. Only after that, provocation of the piriformis muscle can be induced by stretching this muscle. If sciatic nerve symptoms are evoked by this maneuver, consideration of the diagnosis of piriformis syndrome can be entertained.
The piriformis muscle’s action when contracting is to externally rotate the hip. Therefore, the piriformis muscle is stretched (tightened) by internally rotating the hip. Hip internal rotation with flexion while the patient is supine (lying on their back) will reproduce buttocks and leg pain if piriformis syndrome is present.
Conformation is made by a local injection of anesthetic (Lidocaine) and steroid performed under ultrasound guidance with good relief of symptoms. This injection can also yield long-term relief of symptoms.
If the patient has confirmed piriformis syndrome and had failed all the other therapies, a surgical release of this muscle can give long-term relief.
I have yet to consider a patient for this type of surgery.
For more resources on nerve pain and piriformis syndrome, please contact the office of Dr. Donald Corenman, spine specialist and back doctor in the Vail, Aspen, Denver and Grand Junction, Colorado area.
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- How to Describe Your History and Symptoms of Lower Back and Leg Pain
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