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Sciatica is back pain which radiates down into the leg and is caused by pressure on the sciatic nerve. It can be caused by a number of factors although a prolapsed or slipped disc is one of the most common.
The medical term is acute nerve root compression or radiculopathy. The cause of pressure can be varied from a slipped disc (also known as a herniated or prolapsed disc), disc degeneration or muscle tension (Piriformis syndrome) or something less common such as a tumors, bony growths (stenosis) and infections.
A prolapsed disc or slipped disc as it is sometimes known is not simply a disc that has 'slipped' out of place. Intervertebral discs separate the bones of the spine (or vertebrae) and their function is to act as shock absorbers or cushioning for the spine and allow movement.
They quite happily allow flexion and extension (bending forwards and backwards), lateral flexion (sideways movement) and twisting. However a combination of the two can put excess stress on the spine and damage the discs. This is particularly common in people who may lift heavy objects and twist with them for example unloading heavy boxes off the back of a lorry.
The intervertebral discs are filled with a gelantinous substance in the middle called nucleus pulposus and when a disc prolapses this jelly-like centre squeezes out and puts pressure on the spinal cord compressing the nerve routes and causing pain.
Depending on where the sciatic nerve is pinched will determine where you feel the pain, which can radiate to the front of the knee or right down the back of the leg to the foot. The L5-S1 disc is the disc most commonly damaged and the L4-L5 disc the next most commonly damaged. L4 and L5 are the bottom two Lumbar vertebrae at the base of the spine. S1 is the top of the Sacrum.
Piriformis is a muscle found deep in the buttocks. The sciatic nerve runs very close to this muscle. Tension in the muscle can cause compression of the sciatic nerve which can cause sciatic pain in the bum and down the leg.
It is sometimes difficult to distinguish between sciatic pain caused by a disc problem, or caused by piriformis syndrome. Generally with piriformis syndrome there will not be any lower back pain and there is usually a less well defined point of injury.
Read more on piriformis syndrome here.
The treatment of sciatica really depends on the cause of the injury and the extent of the symptoms.
Severe cases (usually caused by a disc prolapse) may require the following treatment:
In less severe cases and those caused by piriformis syndrome, less rest is required:
After the acute painful phase: