Lumbar spinal stenosis means narrowing of the spinal canal, which puts pressure on the nerve roots in the spine. People experience aching or pain in their legs when they walk. This gets progressively worse until people can only walk a block or less. The leg pain is relieved by sitting or by bending forward or squatting. This activity related pain is called neurogenic claudication. Sciatica means leg pain and is usually caused by a disc herniation in the spine that causes irritation of a nerve root. The distribution of the leg pain depends on which level the herniation is at which determines which nerve root is irritated. Epidural blocks involve the injection of cortisone into the spinal canal to reduce inflammation and associated pain. This often provides temporary relief of pain. However it does not make the stenosis or the disc herniaiton go away. Therefore the pain relief is often only temporary but can last for weeks or months.