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by Laura Correa
Sciatica is a term often used to describe any pain that radiates from the back into the leg. True sciatica, however, occurs when the sciatic nerve is pinched or irritated along its length. This nerve, one of the longest in the body, runs from the lower back through the buttocks and down the back of each leg. Its branches innervate different parts of the leg, including the calves, feet, and toes; controlling many muscles of the lower legs as well as providing feeling to areas of the legs and feet. Pain that occurs along this nervešs path is usually caused when the roots that form it are pinched or irritated.
What is it?
Sciatica is a specific form of radiculopathy. A radiculopathy is defined as a disorder of the spinal nerve roots, which are the origins of peripheral nerves at the spinal cord. Nerve roots pass between the bony vertebrae in order to exit the spinal column and travel to the rest of the body. If any of these roots is compressed or inflamed along its anatomic course, the resultant pain is called radicular pain.
Sciatic pain/b>
Sciatic pain can range from mild discomfort to incapacitating. Because it is following a specific nerve path, the most common complaints are pain from the lower back to the knee, pain from the mid-buttocks to the outside of the calf continuing to the top of the foot and into the last two toes, or from the inside of the calf to the inner ankle and sole of the foot. Only one extremity if usually affected. Sciatica complaints often come about gradually and intensify over time. The pain is often a combination of low back pain and leg pain, and often characterized as either a numbness or tingling (like pins and needles), or ranging from a mild ache to a sharp or burning sensation. Others describe the pain as jolting or like an electric shock. Factors that may make the pain worse include sitting, coughing, sneezing, and straining on the toilet, while alleviating actions include walking or lying down. If symptoms include the loss of bowel or bladder control, a much more serious condition called cauda equina syndrome is suspected. This is considered a medical emergency, and medical attention should be sought immediately.
Sciatica is actually a symptom
Sciatica is not really a disorder unto itself; it is actually a symptom of some other problem that is affecting the nerve. The most common cause of sciatica is a herniated lumbar disc. Intervertebral discs are pads of cartilage that separate the bones of the spine, keeping it flexible, while acting as shock absorbers. They are comprised of an outer ring of tough fibrous tissue (the annulus fibrosis) that surrounds a jelly-like center (the nucleus pulposis). When there is a weakening of the outer ring and the inner contents spill out of the disc, it is called a herniated disc. Sometimes this is caused by a sudden twisting motion or perhaps an injury. Discs may weaken, however, with repetitive stress. With advancing age, discs degenerate becoming drier, flatter, and more brittle. These changes make the outer ring more susceptible to injury and to developing little tears. The most common locations for a herniated disc are at the level of L4-L5 (affecting the L5 nerve root) and between L5-S1 (affecting the S1 nerve root). Interestingly, not everyone with a herniated disc has significant discomfort. Only about 35% of patients with a disc herniation will experience true sciatica.
Risk for developing sciatica
There are several factors that may put individuals at risk for developing sciatic pain. Advancing age is the first. By the age of thirty, almost everyone has some disc degeneration. Actual disc herniation usually occurs in the 30s or 40s, whereas spinal stenosis tends to affect those 50 years and older. In addition to age, certain occupations may increase the risk. Any job that requires the twisting of the back or carrying heavy loads is risky, as is spending extended periods of time driving. Some studies indicate that walking/jogging are associated with an increased risk of acquiring sciatic pain, but exercise in general is recommended over a sedentary lifestyle.
Medical therapy
The natural course of sciatica is that is usually gets better on its own. Symptoms can last anywhere from a few days to a few weeks. Because of this, conservative treatment is the best approach. For acute episodes, the goal is to reduce any inflammation and to reduce any pain. Ice, alternating with heat, application for 20 minutes every 2 hours is recommended. Non-steroidal anti-inflammatory medications are used often. Prescription drugs, including stronger anti-inflammatory and muscle relaxants or anti-convulsants, work to block the pain messages to the brain or by enhancing production of endorphins. Corticosteroids can also be injected directly into the epidural space, near the location of the nerve compression to combat the inflammation locally. Physical therapy is used to correct posture, strengthen the muscles that support the back, and to improve flexibility. Surgery is only considered when the pain does not respond to conservative therapy and it becomes chronic (longer than 12 weeks) or debilitating.
Diagnostic tests
Imaging can be a useful tool for investigating the cause of sciatic pain. X-rays are not capable of detecting any problems with the soft tissues around the spine (such as discs) but can detect bony abnormalities of the spine. MRI or CTs are used to see these soft tissues in greater detail.
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