Piriformis Syndrome…an Overlooked Cause of Low Back Pain

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The Piriformis Syndrome is a peripheral neuritis of the Sciatic nerve that is caused by an abnormal condition of the Piriformis muscle.  This muscle is in direct anatomic association with the Sciatic nerve and often masquerades as a lumbar spine abnormality.  It is estimated that 5% to 36% of people with low back pain actually have a Piriformis Syndrome.

 Let me review with you the basic anatomy and physiology of this syndrome.




The Anatomy And Physiology Of Piriformis Syndrome

The Piriformis muscle is a small muscle that attaches the sacrum of the spine (a thick wedge shaped bone) to the hip. It causes the hip to rotate outward, flex, and moves the leg away from the body (called abduction).

The sciatic nerve (a thick nerve that runs down the back of the leg) can run over, through, or under the Piriformis muscle.  The position of the Sciatic nerve can vary from person to person in its relation to the Piriformis muscle.

In most people, the Sciatic nerve runs under the Piriformis muscle.  However, if a portion or all of the nerve runs through the muscle, injury to the muscle can cause inflammation of the Sciatic nerve.  In as much as 22% of all people a portion of the Sciatic nerve runs through the Piriformis muscle.  The clinical picture can be confusing.

Piriformis Syndrome

To make matters even more complicated, people often have multiple mechanisms for their low back pain (such as lumbar disc disease as well as a Piriformis Syndrome).  When it comes to low back pain, the causes are often multiple due to the close proximity of spinal anatomy.




Symptoms And Signs Of The Piriformis Syndrome

The following are symptoms seen in the Piriformis Syndrome (notice that the symptoms overlap with other causes of low back pain):

  • Pain with sitting, standing, or lying longer than 15 minutes.
  • Pain and/or numbness radiating from the sacrum, to the buttock, and down the back of the leg. The pain and numbness does not usually go below the knee.
  • The pain improves with walking and worsens with rest.
  • Pain may worsen when sitting or squatting.
  • The person may have difficulty walking.
  • There may be weakness of the leg.
  • There may be numbness of the foot.
piriformis syndrome
  • There are also a variety of remote symptoms associated with this syndrome such as headache, neck pain, abdominal pain, pelvic pain, inguinal pain, pain with sexual intercourse, and pain with bowel movements.

The following are the physical signs that may be detected with the Piriformis syndrome (these too overlap with other causes of low back pain):

  • Tenderness when pressure is applied to the sacroiliac joint or to the upper portion of the buttock.
  • A palpable mass deep in the buttock.
  • Weakness of the leg.
  • Pain is evoked whenever the hip is maneuvered to apply stretch to the Piriformis muscle.
  • The leg may measure shortened on the side of the Piriformis Syndrome.
  • If the condition is chronic there may actually be atrophy of the Gluteal Muscles.

The Causes Of Piriformis Syndrome

Any force that may injure the Piriformis muscle can cause the syndrome.  The following is a listing of possible causes:

  • Direct compression of the buttocks (such as a fall).
  • External compression from an object (such as in an assault).
  • Gunshot wounds to the buttocks.
  • Sitting for long periods of time.
  • Sitting with a large wallet in the back pocket.
  • Vascular disease which compromises the blood flow to the Piriformis muscle.
  • Long distance running.
  • Long distance walking.

The Diagnosis Of Piriformis Syndrome

The diagnosis of the Piriformis Syndrome is made on a clinical basis.  There is no specific diagnostic study that definitively diagnoses this syndrome.  The diagnosis can only be made by a thorough history and physical.

If the patient permitted, and there were no contra-indications, I would usually inject the Piriformis muscle with my special mixture of Marcaine (a local anesthetic), Depo-Medrol (a corticosteroid to treat inflammation), and Sarapin (an herbal anti-inflammatory from the Pitcher plant).

When a patient had a true Piriformis Syndrome, the injection gave immediate relief of the pain and confirmed the presumptive diagnosis.

the diagnosis of piriformis syndrome
The Treatments For Piriformis Syndrome

The following treatments for Piriformis Syndrome have been found to be effective:

exercises for piriformis syndrome

For cases where the pain is extreme I would usually consider an injection of the Piriformis muscle.  The technique would be performed as follows:

  • Place the patient in the prone position (lying on their stomach).
  • Identify the Piriformis muscle by palpating the buttock halfway between the edge of the sacrum and the hip.
  • Skin prep the patient with alcohol or betadine.
  • Sterile drape the patient (I used fenestrated sterile fields that were disposable. They had a pre-cut circular opening in the center of the sterile drape).
  • Draw up your injection solution (remember I used a mixture of 1cc Marcaine 0.25% : 1cc Depo-Medrol 40 mg per cc : 1cc of Sarapin). The total volume of injection would be 3cc. I would draw up the mixture into a 3 cc sterile single use syringe using an 18-gauge needle.  After drawing up the mixture I would remove the 18-gauge needle and replace it with a 20-gauge bevel tipped spinal needle.  Depending on the thickness of the buttocks of the patient, a spinal needle would have the length necessary to guide the needle tip close to the Piriformis muscle.
  • Use Sterile single use latex free gloves. One hand (the non-dominant hand) would be used to palpate the tender Piriformis muscle.  This hand would remain “sterile” so that it can be used on the sterile field.  The dominant hand would hold the syringe and be used to inject the mixture.  It is technically a “contaminated” hand (holding the syringe).

THE ACTUAL INJECTION IN THIS MANNER

DEPENDING ON THE SENSITIVITY OF THE PATIENT, WE WOULD OFTEN PLACE A SMALL WHEAL OF LIDOCAINE INTO THE SKIN AT THE PUNCTURE SITE. THE MORE COMFORTABLE YOU MAKE THE PROCEDURE THE MORE LIKELY THE PATIENT WILL HAVE A REPEAT INJECTION.

WE CAREFULLY INSERTED THE SPINAL NEEDLE ATTACHED TO THE SYRINGE AND SLOWLY ADVANCED THE NEEDLE PERPENDICULAR TO THE SKIN AT THE LOCATION WHERE WE PALPATED THE PIRIFORMIS PAIN.

injection of piriformis syndrome

AS WE ADVANCED THE SPINAL NEEDLE, WE WOULD BALLOTTE THE PLUNGER OF THE SYRINGE. THIS CAUSED A SMALL COLUMN OF FLUID TO LEAK OUT OF THE NEEDLE TIP CAUSING A MILD NUMBNESS OR TINGLING TO BE FELT BY THE PATIENT WHEN WE NEARED THE SCIATIC NERVE.

WHEN THE PATIENT REPORTED FEELING THIS, WE WOULD PULL THE NEEDLE BACK 5 MM AND SLOWLY INJECT THE MIXTURE. THIS AVOIDED DIRECT INJECTION INTO THE SCIATIC NERVE (WHICH COULD CAUSE DAMAGE TO IT). THE 3 CC VOLUME WAS INJECTED INTO THE SOFT TISSUE NEAR THE PIRIFORMIS RESULTING IN IMMEDIATE RELIEF OF PIRIFORMIS PAIN.

WE DID NOT INJECT IF THE PATIENT REPORTED INCREASING PAIN OR NUMBNESS. IF THIS OCCURED, WE WOULD WITHDRAW THE NEEDLE AN ADDITIONAL 5 MM AND REATTEMPT THE INJECTION.

THE MANY TİMES OF PERFORMING PIRIFORMIS INJECTIONS IN THIS MANNER, WE WAS ABLE TO ALWAYS ACHIEVE PAIN RELIEF FOR THE PATIENT AND NEVER HAD ANY INJECTION RELATED INFECTIONS OR COMPLICATIONS. THIS WAS THE TECHNIQUE THAT WE FOUND SO EFFECTIVE FOR PIRIFORMIS INJECTIONS.

For cases where none of the above treatment modalities are ineffective, the patient will need referral to an Orthopedic surgeon for possible removal of the Piriformis muscle.

This is an extreme treatment measure for PS which we never had to resort to in the entire history of us practice.

Concluding Remarks

We have discussed the definition of PS, anatomy and physiology, symptoms and signs, causes, diagnosis, and treatment. PS is an often overlooked cause for low back pain.

I hope you have found this article helpful. If you have any further questions, please comment.I would love to hear from you and will answer you promptly.

Wishing you joy and healing.