Conditions treated: sciatica and leg pain

What is sciatica?

Sciatica is a sharp shooting pain felt in the buttock, which radiates down the back of the thigh below the knee and into the calf and/or foot. It can be divided into unilateral sciatica (one leg only), or bilateral sciatica (both legs).

It is usually caused by direct nerve root compression, and in particular compression of either the L5 or the S1 nerve roots. “L” stands for lumbar and “S” stands for sacral. The “5” refers to the 5th lumbar nerve root is obviously the last and lowest lumbar nerve root, and the “1” refers to the first sacral nerve root. The commonest cause of this is a disc herniation at either the L4/5 level or L5/S1 level. Nerve root irritation can also be caused by chemicals released as a response to the disc herniation, and can be associated with a tear in the outer part of the disc known as the annulus.

Interestingly S1 root compression can present solely with buttock pain. It is not necessary for the pain to go down below the knee and it often only passes into the back of the thigh. It can often be mistaken for a hamstring sprain, and often a spinal injection may prove to be both diagnostic as well as therapeutic.

Fortunately in the majority of cases sciatica will resolve within 6 weeks and I do not routinely intervene before 6 weeks unless there is significant neurological compromise or evidence of progressive neurological loss. However, if a patient has developed cauda equina syndrome then it is considered a surgical emergency. Additionally if a patient has sciatica in both legs (bilateral) then I am more worried as they may have a large central disc, which needs to be investigated more urgently.

Obviously as sciatica and leg pain is basically caused by nerve root compression, anything that causes direct compression to the nerve can cause leg pain and sciatica. This includes spinal stenosis and spondylolisthesis, as well as the commoner causes such as a disc herniation.

Red flags are signs and symptoms which point to a serious cause of the leg pain, such as trauma, tumour or infection. These causes would manifest themselves as either constitutional symptoms such as fever, rigors, weight loss or unremitting pain suggesting imminent vertebral collapse, as well as the leg pain and sciatica. Fortunately these are rare but if there is a history of previous malignancy (cancer) or use of long-term steroids then it is important to be suspicious.

How I treat sciatica obviously depends on its cause.