Arachnoiditis is a pain disorder caused by inflammation of the arachnoid, one of the membranes that surrounds and protects the nerves of the spinal cord. The inflammation may occur due to irritation from chemicals; infection; direct injury to the spine; chronic compression of spinal nerves; or complications from spinal surgery or other spinal procedures. It may result in scar tissue and adhesions, which cause the spinal nerves to 'stick' together. If Arachnoiditis affects the function of nerves, it can cause symptoms such as numbness, tingling, and a characteristic stinging and burning pain in the lower back or legs. In some people, it may affect the bladder, bowel, and sexual function. Very severe Arachnoiditis can result in paralysis of the legs.