Sciatica is pain shooting down the sciatic nerve as it runs from the low back down the buttock and the leg, either on one side or both sides. Sciatica often occurs when a herniated disc puts pressure on the sciatic nerve as it exits the spinal canal in the low back. Sciatica is a specific type of radiculopathy (compression or irritation of nerves as they leave the spinal column). Sciatica can be associated with spondylosis because the degenerative changes in the spine predispose to disc herniation and subsequent nerve compression.