Piriformis Syndrome Part One – What Is It?

First off, we don’t call it Piriformis Syndrome anymore. It is now called Deep Gluteal Syndrome (DGS) because there are more things than just the Piriformis muscle that can cause this pain and numbness you may be experiencing

Deep Gluteal Syndrome describes pain or numbness in the buttock caused by entrapment of the sciatic nerve. This means the sciatic nerve isn’t getting pinched by a disc herniation in the lumbar spine or anything inside the pelvis. The sciatic nerve exits the pelvis through the sciatic notch, so DGS refers to entrapment of the nerve as it exits the notch or travels on through the buttock into the leg.

Our understanding of the anatomy and function of the posterior hip area has shown us that are many potential causes of pain in the buttock and referral down the back of the leg.

The three most common causes, accounting for approximately 80% of cases, include:

1. Piriformis Syndrome (~68%)
2. Distal foraminal entrapment (~6%)
3. Ischial tunnel entrapment (~5%)

For our purposes today, let’s talk about Piriformis Syndrome because that is by far the most common cause of pain or numbness in the buttock +/- referral down the leg.

The picture below shows the piriformis muscle located in the middle of your buttock. The star marks the most common site of pain and tenderness. The shaded area shows where you can experience referred pain from the injured muscle or if the muscle is causing sciatic nerve entrapment.

Pain is typically focused in the buttock but may extend down your leg.

The piriformis is a small muscle in the back of your hip. It can be found in the middle of your buttock, underneath the larger Gluteus Maximus muscle. Its main function is to stabilize the hip and externally rotate it. External rotation means turning your leg at the hip so that your toes point outwards.

It is also an important muscle because it crosses the sacroiliac joint, so can act to stabilize and control that important pelvic joint’s movements.

One other important thing to know is that several nerves pass either underneath, above or through this muscle. This includes the sciatic nerve (that goes down the back of your leg to your foot) as well as the gluteal nerves that tell your buttock muscles how to work as well as supply sensation to the skin over the buttock and hip.

This is a fancy term to describe how nerves move and glide as we move. We are designed and built to move, which requires our soft tissues to slide against each other. Problems arise when our anatomy changes, and impedes the ability of the nerves to move properly. These authors determined that neuropraxia (disturbance in the sensory or motor function of the nerve) occurs with as little as 6% strain and total blockage can occur with 12% strain.

Let’s think about some common hip movements. Deep hip flexion, such as when we squat or bring our knees to our chests, require the sciatic nerve to slide and lengthen as much as 3 cm (28 mm). So imagine you are lying on your back and draw your knee to your chest. Your sciatic nerve needs to slide further out of your pelvis to lengthen enough for this range of motion. If something is tethering it, strain will occur.

Let’s keep going. From that position where your knee is drawn to your chest, now allow the knee to drop to the outside, keeping your knee bent. This movement requires the sciatic nerve to slide around the back of the greater trochanter (the big bone you can feel on the outside of your hip). If there is anything restricting the nerve’s ability to move, you may experience a “snap” or twinge of discomfort when you do that movement.

Now, take it one step further. From that position (lying on your back with your hip flexed and knee dropped to the outside), if you begin to straighten your knee, the sciatic nerve will then need to slide back off the posterior aspect of the greater trochanter, into the ischial tunnel.

Anything that gets in the way of the sciatic nerve’s ability to move and slide is considered an entrapment, which leads to the nerve becoming sensitized, which can cause pain, numbness or tingling. These symptoms can occur locally, where the entrapment is occurring (i.e. in the buttock and back of the hip) or anywhere along where the nerve travels (i.e. down the leg).

Things that can happen if the piriformis muscle is misbehaving include:

• Buttock pain
• Leg pain
• Low back pain
• Hip pain and dysfunction
• SIJ (Sacroiliac joint) pain and dysfunction
• Sciatic nerve pinching/compression and irritation

Because of the piriformis’ location, you may experience more pain when you are sitting because you are putting direct pressure on the muscle. This is especially true when you are driving because the driving position typically creates a double whammy. You are sitting with direct pressure on the muscle but most of us allow our foot to flop out when it is resting on the gas peddle. That external hip rotation posture allows the piriformis muscle to be in a shortened position for long periods. Chronically shortened muscles typically don’t contribute to a health and pain-free lifestyle…just sayin’ 😉

As mentioned, Piriformis Syndrome is somewhat of a controversial diagnosis. Here are some other things that can give you similar buttock (and leg) pain:

• Sciatica
• Referred pain from the joints, muscles and other soft tissues in the lower back
• SIJ sprains and strains
• Cluneal Nerve syndromes (Neuralgias)
• Hip joint arthritis

Buttock pain is really common and needs to be properly assessed and diagnosed by one of our chiropractors before you can hope to figure out which treatments will be best.

The other thing to consider is whether the piriformis muscle is the culprit or the victim?

A important thing to keep in mind is that your piriformis might be getting over-tasked by compensating for something else that isn’t functioning properly. This is a big topic and this forum certainly isn’t the place to go into all the various ways our chiropractors can see how the poor, little piriformis muscle is getting bullied by other areas not doing their job.

The way we try and sort that out at our Calgary clinic is by following two concepts called reciprocal inhibition and synergistic dominance.

I go through an explanation of these two terms in this video. If you don’t want to watch the full exercise session I cover in this video workshop, the info share goes from 2′ 50″ mark all the way up to about the 9’30” mark.

Buttock pain radiating down the leg can be caused by entrapment of the sciatic nerve by structures deep in the back part of the hip. The piriformis muscle is one of those structures and is one of the more common causes of Deep Gluteal Syndrome (formerly called Piriformis Syndrome).

SPOILER ALERT: I actually have experienced this problem off and on over the years so stay tuned for future articles, where I will get into some treatments and fixes.

Step one is to go through a proper assessment to determine if this is actually what is causing your pain. Once properly diagnosed, a care plan can be organized to chart a path out of pain and back to normal function.

1. Martin HD, Reddy M, Gómez-Hoyos J. Deep Gluteal Syndrome. J Hip Preserv Surg. 2015 Jul; 2(2): 99-107. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4718497/
2. Coppieters MW, Alshami AM, Babri AS, et al. Strain and excursion of the sciatic, tibial, and plantar nerves during a modified straight leg raising test. J Orthop Res 2006; 24: 1883–9. [PubMed] [Google Scholar] [Ref list]
3. Martin R, Kivlan B, Martin HD. Greater Trochanter-Ischial Impingement: A Potential Source of Posterior Hip Pain. Rio de Janeiro: International Society for Hip Arthroscopy, 2014. [Google Scholar] [Ref list]