Is my Sciatica Caused by a Spinal Issue or my Piriformis Muscle?

Orthopaedic & Spine Center

Mark W. McFarland, MD

Sciatica is a catch-all term that is used for pain that runs from the lower back through the buttock, down the thigh and calf, into the foot.  It is named thusly after the sciatic nerve, which when compressed, inflamed, or irritated in some way, causes the tell-tale signs of burning, numbness, tingling, pain and weakness in the rear, leg, calf, and foot.  But how do you know when this pain is caused by an issue with the spine or something else is at play?  In this article, I will discuss how I discern whether a patient has a spinal issue OR if they have an inflamed muscle, known as the piriformis.

First, an anatomy lesson.  The sciatic nerve (SN), the longest and largest nerve in the body, emerges from the bony vertebral column at L4 to (Lumbar vertebrae 4 to Sacral level 3).  A bundle of sensory and motor nerve fibers, the SN provides for most every function of the leg we use in our daily lives – walking, running, bending, pointing and flexing the toes, sensing temperature and feeling touch.

To protect it from injury, the SN is embedded deep within the musculature of our buttocks, leg, and calf. In the buttocks, it passes over, under, or may split around the piriformis muscle and join back together, depending upon a person’s individual anatomy.  It then travels down the rest of the leg, through the calf where it terminates in the foot.

When a patient comes to my office complaining of classic sciatica symptoms, it is my job to be a detective and follow the clues to ascertain whether their pain is being generated by an issue with the spine or with the piriformis muscle.  After a thorough physical examination and x-rays, multiple physical movement and sensory tests, and asking a lot of questions about activity level, fitness, work, etc., I typically will have a good idea what is generating the pain.

When the nerve root is involved (spine issue) the symptoms will typically be pain and numbness on the outside of the leg and perhaps a loss of feeling between the great and lesser toe.  I may or may not be able to see anything out of the ordinary on x-ray.  I may see some narrowing of the intervertebral space or a bone spur.  I may see some spinal stenosis (narrowing of the spinal canal) or a slipped bone (spondylolisthesis). 

The key difference when the piriformis muscle is involved, is that the patient will be extremely sore to the touch and may have swelling or muscle spasms in the affected buttock.  They may have also reported a recent injury or that they ran a lot before this pain started.  They may also sit a lot for work.  The patient may also report that the pain worsens after inactivity.  They will also have burning, tingling and numbness, but it may be more widespread and diffuse.  Piriformis syndrome typically affects more women than men.

Treatment for these two issues may be quite similar at first.  Behavior modification, physical therapy, anti-inflammatory medications, oral steroids, and other pain-relieving therapies, such as hot/cold packs, massage, hot baths or showers, stretching, gentle exercise and rest will be recommended for the first 3-4 weeks.  Reducing inflammation of the sciatic nerve will be key.

For spine issues that do not resolve, I order an MR scan to further visualize what is happening with the soft tissues (spinal discs, nerves) that x-rays do not reveal.  An epidural steroid injection at the nerve root is often the next step to treat inflammation directly at its center.  If the MR scan revealed a bulging or herniated disc or other structural issue, surgery may be needed to alleviate the compression on the sciatic nerve to prevent permanent nerve damage.

For recalcitrant piriformis syndrome, injections of steroid medication can be made directly into the piriformis muscle under fluoroscopy (live x-ray).  This procedure is performed in our sterile, procedure suites in our office.  I numb the area with a local anesthetic and using x-ray guidance, place the medication exactly at the site where the piriformis muscle intersects the sciatic nerve, for maximum effectiveness.  These injections usually quiet even stubborn inflammation to allow the irritated sciatic nerve time to heal.