True sciatica is caused by irritation and / or inflammation of the sciatic nerve or the nerve roots that branch off the spinal cord and mesh together to form the sciatic nerve. Irritation is caused by some sort of mechanical pressure on this delicate nerve tissue. Pressure can occur in a variety of ways at different locations along the distribution of this very long nerve. Some of the more common causes of sciatica are:
In any situation, sciatica is a mechanical lesion that is experienced as pain in our brains. Pain receptors travel from the site of pressure up through the spinal cord and make us consciously aware of pain when these messages hit our primary somatosensory cortex in the parietal lobe of our brain. Pressure anywhere along the sciatic nerve may be perceived as pain along the entire distribution of our sciatic nerve.
A pinched nerve is the common wording for the pressure, irritation and inflammation of the nerve roots.
Lumbar Spine Disc Degeneration. Refer to the ‘annular tear’ section of my previous blog “Acute Sposmotic Low Back Pain – Part 1”. Put simply, when lumbar spinal discs degenerate, the inside of the disc can bulge, protrude or herniate outwards and impinge on the lumbar nerve roots.
Spinal Osteoarthritis. The change in the shape of the bones of the spine (vertebrae) that occurs with spinal osteoarthritis may cause nerve root irritation. The facet joints at the back of the spine can become enlarged and create a tortuous pathway for the nerve roots, creating stretching and irritation.
Spinal Ligament Thickening. Some of the ligaments that hold the spine together can become thickened over time. Ligamentum flavum is a great example. This can create less space in the spinal canal (stenosis) and some degree of pressure on the nerves within the canal.
Muscular Tightness / Shortening. Interestingly, the most common cause of sciatica falls into this category. Piriformis Syndrome probably deserves its own blog, but it occurs when the trunk of the sciatic nerve gets pressure on it as it moves through the gluteal region. The piriformis muscle is an external rotator of the thigh and activities that involve rotating the foot outwards regularly or for prolonged periods of time may amount to pressure on the sciatic nerve through muscle tightness and contracture. Excessive periods of sitting may create a more long-term shortening of the piriformis muscle and is another reason why we should not spend our entire day sitting.
If you are experiencing pain in the back of your thigh and / or leg, it is extremely important to receive a thorough assessment and correct diagnosis of sciatica and, furthermore, the cause of your sciatica. Depending on the cause of your sciatica, surgery may be an answer, but I suggest that it should be an option that is considered only after all conservative approaches are employed. An active lifestyle, specific stretches, weight management and dietary advice, together with chiropractic care may just be a very effective way to get back on track.
by Catalyst Chiropractic
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