Why does sciatica occur?

Sciatica is a symptom that there is a problem with the sciatic nerve. The sciatic nerve exits the pelvis on either side through the sacro-sciatic foramen. It passes under the piriformis muscle. The nerve continues down the back of the thigh divides into two nerves about mid-thigh and continues down the leg to the heel. There are several structures that can cause pressure on the nerve which causes pain. A classic symptom that it is sciatica is a burning, sharp feeling that travels down the back of the leg to the back of the knee or all the way to the heel.

One of the structures that can press on the nerve is a vertebral disc located in the spinal column. A disc may rupture causing either the jelly inside to press on the nerve or a piece of the disc itself to press on the nerve. Some causes of the rupture are: a blow to the back, lifting something heavy, twisting the spine, or a pathological weakness in the bone structure. Physical therapy, light exercise, and analgesics are primarily the first treatment for sciatica. Surgery is usually the last option.

Another cause of sciatica is the piriformis muscle pressing on the nerve. The piriformis is located in the buttocks and stretches over the sciatic nerve. Sometimes this muscle may spasm causing it to clamp down on top of the nerve causing the sciatica pain. This can happen from sitting too long on a hard surface, pulling the muscle during exercise, or even a wallet in the back pocket.

As the body ages, the spinal column may narrow. This is called spinal stenosis. If this happens, especially at the lumbar region, it will affect the sciatic nerve. With this problem sitting may alleviate the pain, whereas, with the other causes of sciatica sitting may aggravate the condition.

A few rare causes of sciatica are lesions or tumors along the nerve. Lesions can cause pain and then paralysis of the muscles of the foot. Tumors may also be responsible for pain and paralysis along the nerve. The tumors may originate in the spinal cord and travel along the nerve.

Sciatica is most common in women. Women who are pregnant may experience sciatica as the fetus grows and presses on the nerves in the pelvis.

Although sciatica can be extremely painful it does resolve after a while. Mild exercise, the use of anti-inflammatory medicines, and alternating heat and ice will help.