What are sciatica and piriformis syndrome?
Sciatica is a word that gets thrown around a lot. It comes up in yoga often when someone has pain in their low back or down the back of their leg. They make a jump to saying, oh that pain must be sciatica. In this article I’d like to take that apart a little bit. I’ll discuss the various reasons someone might feel pain and the differences between sciatica, piriformis syndrome, and other potential sources of pain.
First of all, since we’re talking about pain, it feels important to say that yoga should never involve excruciating sharp pain. So, if you are feeling intense, sharp, nervy types of pain in the buttocks, down the back of your leg, and/or in the low back during practice, which is making you think you might have sciatica, stop and change your practice. Back out of the asana where you’re experiencing the pain or substitute a different asana with the same intention that doesn’t cause pain.
Pain in the low back is a minefield. It can come from many sources, including sources that are outside of the low back itself. I won’t try to cover all of those kinds of back pain here. That’s for a different post. The kind of back pain that I’ll include in this post is a nervy kind of pain. It’s felt in the low back, buttocks, and often in conjunction with a nervy pain that shoots down one or both legs. This kind of pain can be associated with the condition sciatica. But it can also result from other conditions. So what’s the difference, and how can we tell them apart?
The sciatic nerve
The sciatic nerve runs out of the sides of the vertebrae in the low back, underneath the piriformis muscle (although there is some variability in this among people and some people have a sciatic nerve that runs through the piriformis muscle), and then ultimately down the back of the leg. It innervates the three hamstring muscles and a portion of adductor magnus. Its branches below the knee (the tibial nerve and the peroneal nerve) innervate the lower leg and some muscles in the foot.
The piriformis muscle
Remember that the piriformis muscle is one of six muscles in a group known as the deep 6 lateral rotators of the hip joint. It attaches at one end to the anterior sacrum. On the distal end, it attaches to the top of the femur at the greater trochanter. And as I said above, piriformis lies across and just superficial to the sciatic nerve, that major nerve that feeds the back of each leg.
Both sciatica and piriformis syndrome involve compression of the sciatic nerve, so they have that in common. One of the main differences between the two is where the compression is coming from. The term sciatica is generally used in one of two ways. It’s used generally to describe a collection of symptoms that occur when the sciatic nerve is compressed. And, it’s used more specifically to describe the situation when a vertebra, or a disc sitting between the vertebrae (often a herniated disc), is compressing the sciatic nerve.
Piriformis syndrome on the other hand, as the name suggests, involves the compression of the sciatic nerve by the piriformis muscle. This can happen for more than one reason. A common one is simply overuse or shortness of the piriformis muscle (and likely the other deep six lateral rotators too). Overuse, or simply a tight muscle, could happen from athletic activities or from repeated activities during the work day depending on what work tasks someone does.
Is it sciatica or piriformis syndrome?
It’s helpful to be able to differentiate between sciatica and piriformis syndrome. As it turns out there is a simple way of doing this. The accuracy of the test is good. But please don’t confuse this test with being a doctor and producing a diagnosis. Use the results as information and continue to proceed with caution if you or a student wants to try and differentiate between the two.
The simple test to differentiate between sciatica coming from the spine, possibly disc compression, and the piriformis compressing the sciatic nerve, is this: Lie on your back. Lift the leg of the affected side. If you can lift your leg higher than a foot off the ground there is a good chance that your piriformis is tight. If you lifted your leg and within six inches you had shooting pain down the back of the leg, it’s more likely the pain is coming from the nerve being compressed closer to the spine.
Why the difference?
Your nerves stretch along with your myofascia (muscles and connective tissues). The positioning and nature of the piriformis will allow the sciatic nerve to stretch more or less uninhibited. If the compression is from a disc or even vertebrae at the spine, it’s generally less forgiving. As the nerve is stretched while being compressed by either of these structures, it will send a shooting sensation down the back of the leg. Again, this is for information gathering rather than making a positive diagnosis of your own or someone else’s pain.
Other sources of sciatica-like pain
There are other trickier sources that can mimic a similar type of pain to sciatica. These sources are trigger points. Trigger points in gluteus minimus and gluteus medius can result in sciatica-like pain. Travel and Simons, 1993, note that one situation in which this is common is when someone is sitting on a wallet on one side of the body every day. Those pressure points from the wallet can create trigger points. Or, they can aggravate trigger points that are already present. Trigger points in the piriformis muscle can also refer sciatica-like pain.
One of the main ways to distinguish between trigger points and something actually pressing on the sciatic nerve is the pain pattern. When something is pressing on the sciatic nerve, whether it’s bony or muscular, the pain often continues nearly all the way down the leg. The pain pattern from trigger points tends to be more localized. It may go just down the thigh, or only part-way down the thigh. The pain pattern from trigger points in gluteus minimus specifically tends to go more down the side of the leg, rather than the back of the leg. So that can help you distinguish between the possible sources of the pain.
How to manage yoga and sciatica-type pain
First of all, as I said earlier in the article, if you are experiencing sharp pain for any reason during yoga practice, stop what you’re doing. Can you modify the posture in a way that doesn’t cause any pain? If so, do the modification. And, if that isn’t an option, can you choose a different posture with a similar intention that doesn’t cause pain? If so, do the other pose. Opening the deep six lateral rotators, especially piriformis, can help alleviate intermittent pain from a short, tight muscle pressing on the sciatic nerve. If yoga or any other stretching is not making things feel better, or if the sciatica-type pain symptoms are showing up outside of yoga during the day, then it’s probably time to see a medical professional and get a thorough assessment of your situation.
Travell, J.G and D.G Simons. 1993. Myofascial Pain and Dysfunction – The Trigger Point Manual. (Volume 2). Lippincott, Williams, and Wilkins.