Sciatica: The Common Knowledge Enigma

(Originally posted on bcotoronto.com on Oct 27th, 2011)

Continuing along last week’s promise to explore more traditionally chiropractic grounds we will be discussing leg pain this week. More specifically we will be talking about Sciatica. Many people talk about Sciatica and Sciatic pain but do they really know what exactly it is? The term Sciatica comes from the main nerve running down the back of our legs called the “Sciatic” Nerve which supplies the sensation and the muscle control to ¾ of the leg. It is very large and formed by the conglomeration of multiple nerves coming out of the spine before they leave the pelvis. The Sciatic nerve leaves our pelvis out the back and passes beneath the Gluts and runs between your hamstrings to the back of the knee where it splits up again and smaller nerves go off to other parts of the leg.

Nerves have a typical organization to them where fibres around the outer edge of the nerve carry information about sensations (vibration, pain, temperature, pressure) and the inner fibres carry signals for our muscles. So when a nerve is put under pressure this first impacts the sensation causing pain and pins and needles most commonly. This is exactly what happens with Sciatica. Somewhere along its route the nerve or one of the spinal nerves feeding it is impacted by something and causes pain felt over where those nerve fibres are headed.

But, as with most things in health, it’s not that simple. On most people, the distance from the low back to the back of the knee is about a foot and a half to two feet. So where is the nerve compressed? How can we tell and what does that mean for us? There are several common sites where the nerve can become squished.

The most common of these sites is under a muscle called the “Piriformis” which is a small muscle about the size of two fingers that covers the hole in our pelvis where the Sciatic nerve exits. If the Piriformis is tight then it can press down on the Sciatic nerve causing compression and pain.

Inside the pelvis the nerves that come together to form the Sciatic nerve run along the back edge on top of the muscles and both the nerves and the muscles are covered in thin layer of connective tissue (the non-descript tissue that holds all the specific tissue together). Because they are covered like this if the muscles spasm or tense up too much this can cause compression of the nerves and leg pain. Conversely, conditions where the abdominal organs or arteries become enlarged can compress the nerves. These are uncommon but do occur.

As we discussed last week, Disc Herniations can press on the spinal cord or on the nerves exiting the spine causing significant nerve pain. If this happens to any of the spinal nerves involved in forming the sciatic nerve, “Sciatica” can develop. But this is not true Sciatica and, as we talked about last week, needs medical attention.

So if you have leg pain you may be suffering from Sciatica but it may something else masquerading as Sciatica which can be quite serious. If you ever have pain that you can’t you can’t explain or is disproportionate to the injury that caused it, go see a health professional. Nerve pain follows patterns that doctors have been trained to identify and evaluate to determine the source of pain. Depending on the cause different treatments may be necessary. Chiropractic can help if the compression is caused by muscles or a disc bulge. Through adjustments and vigorous muscle relaxation techniques compression can be alleviated fairly easily.

Thanks for reading,

Dr. Ben

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