Sciatica is often described as pain that radiates along the path of the sciatic nerve. This is the largest nerve in the body, beginning at the lower back, and running through the hips and buttocks down to each leg. In most cases, sciatica affects only one side of the body, but can affect both (bilateral sciatica). Where symptoms are felt in both legs, it typically means that the cause of the compression, such as a herniated disc, is big enough to compress nerve roots on both sides of the spine.
