Defined as inflammation or injury to the sciatic nerve resulting in radiating pain from the back/buttock region down the back of the thigh potentially spanning all the way to the toes. Depending on the lumbar spine level, other nerves can become inflamed leading to differing patterns of painful radiating pain (i.e., down the front of the thigh, shin, or hip).
Common causes of nerve damage leading to sciatica include bulging or herniated discs, bone spur growth, stenosis of both the inner spinal canal or the holes in which the nerves exit, and piriformis syndrome.
Less common causes are nerve diseases like multiple sclerosis, direct compression injury (sitting on a wallet), scar tissue from surgery, and tumors compressing the sciatic nerve. If left untreated sciatica can result in leg muscle strength loss and even atrophy (permanent muscle damage).