Sciatica. You’ve probably heard of it before. Maybe you have even experienced it yourself. But what is sciatica, really? Let’s take a dive into anatomy to find out.
On each side of your spine, you have nerve roots that branch out and form different nerves that communicate motor function and sensation throughout the various parts of the body. One of such nerves is the sciatic nerve. It is formed from the nerve roots of L4 through S2. Each vertebral level of the spine is labeled based on its location.
You have:
7 cervical vertebrae (vertebrae are the bones of the spine)
12 thoracic vertebrae
5 lumbar vertebrae
4 sacral vertebrae (the 4 sacral vertebrae are actually fused together and called the sacrum)
(Image courtesy of the National Cancer Institute)
At each vertebra, there's a nerve root above and below it. At the lumbar spine and sacrum, the nerve roots are numbered based on what vertebra is above the nerve root. So in the case of L4 through S2, this means that the sciatic nerve draws from the roots of L4 (lumbar 4), L5 (lumbar 5), S1 (sacral 1), and S2 (sacral 2).
The sciatic nerve happens to be the largest nerve in the human body As mentioned it draws its roots from L4-S2. It’s formed along the low back and travels through the buttocks, into the back of the thigh and even to the knee until it branches off into several different nerves in the lower leg. Some of these even travel all the way to the foot. Sciatica draws its name from the sciatic nerve. Essentially sciatica is irritation of the sciatic nerve. This irritation can cause pain, weakness, numbness, and/or tingling throughout the entire route of the sciatic nerve.
Now there are a few important things to note. First, true sciatica goes into at least the thigh if not the lower leg and foot. This means that if you’re having back pain or even buttock pain, it’s likely NOT sciatica. Second, SCIATICA IS A SYMPTOM, NOT A DIAGNOSIS ON ITS OWN. Saying that someone has sciatica is like saying someone has a cough . It doesn’t actually offer any information about the cause. As such, treating just the symptom can often lead to lackluster results (if any). Third, if sciatica is lingering around, you must figure out the cause to address the issue. Going back to our coughing example, treating just the sciatica would be like just throwing allergy medicine at someone for a cough without determining if it’s allergies, common cold, flu or some other respiratory ailment.
So what are some common causes of sciatica? Arguably the most common cause of sciatica is some kind of disc pathology. You’ve probably heard of those too. Between each bone of our spine (except the levels of the sacrum since it’s fused together), there is a disc that serves as a shock absorber while also allowing for movement between the various levels of the spine. This disc is made of a “soft” center called the nucleus pulposus and tougher fibers surround the center called the annulus fibrosus. At times the disc can start to bulge or even herniate, possibly leading to some pressure being placed on the nearby nerve root. This pressure may lead to some irritation which then travels down the associated nerve. This would be sciatica if that nerve happens to be the sciatic nerve.
Other causes can include:
Build up of bone around the space where the nerve roots exit the spine
Build up of bone around the space where the spinal cord travels through
Direct trauma to the nerve
Spondylolisthesis, which is a condition where the entire vertebra actually moves forward in relation to the rest of the spine.
Today though, we’re going to really focus on the disc as this is the most common cause.
Now if you have ever heard anyone refer to your disc as being fragile like a jelly donut, ignore it and forget it. Discs are resilient and often can heal. Disc bulges even occur commonly in people who don’t even have symptoms. A meta analysis in 2015 (a meta analysis is one of the strongest levels of evidence when it comes to research) found that 20% of young adults who had ZERO PAIN happened to actually have disc bulges. This went up to over 75% for people in the 70s! Disc degeneration (you’ve probably heard that one before too) ranges from 30% to 95% in people WITHOUT SYMPTOMS. See below for the citation and the link to the study.
This isn’t to dismiss anyone’s pain. If you have had sciatica before, you know that it can hurt like hell. The great thing is that it is very treatable in most cases. Now what can you do about it?
First, do not force your body into positions that really reproduce or exacerbate your symptoms. I’m not one to typically say “no” to pretty much any movement or exercise but this is one of the few exceptions as forcing movement here will likely just make that sciatic nerve more angry. For those of you that like to really stretch your piriformis or feel the need to stretch your hamstrings when dealing with sciatica, stop, like now. Often, placing increased stretch on an irritated nerve will temporarily make it feel better but then it may come back with a vengeance. Under normal circumstances it is totally fine to stretch these areas but hold off for now while that sciatic nerve is still irritated.
Any movement that does not provoke your symptoms is fair game to continue. If it’s only been a few days that you’ve been experiencing sciatica, do not panic. Figure out which movement patterns are causing your pain and temporarily modify them. Often just by doing this, symptoms can be alleviated. If the pain starts to linger beyond those first few days, then it would be wise to find someone who will do a very thorough assessment to help you find the cause and plan a path forward.
If this is you, I happen to know a decent PT who can help you…
Best,
Ryan
This article is not intended to be a replacement for medical professional advice nor a substitute for a full evaluation by a medical professional. This article is intended for educational purposes only and the videos associated with this article are for educational purposes only. When attempting any movements that are suggested in this article or associated videos, you are performing that at your own risk and the author of this article cannot be held responsible.
Brinjikji W, Diehn FE, Jarvik JG, Carr CM, Kallmes DF, Murad MH, Luetmer PH. MRI Findings of Disc Degeneration are More Prevalent in Adults with Low Back Pain than in Asymptomatic Controls: A Systematic Review and Meta-Analysis. AJNR Am J Neuroradiol. 2015 Dec;36(12):2394-9. doi: 10.3174/ajnr.A4498. Epub 2015 Sep 10. PMID: 26359154; PMCID: PMC7964277.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7964277/#:~:text=The%20prevalence%20of%20disc%20bulges,than%2070%20years%20of%20age.&text=Our%20meta%2Danalysis%20found%20a,and%2043%25%20of%20symptomatic%20populations.
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