What is Ankylosing Spondylitis (AS), Neurologic Perspective?
Ankylosing spondylitis (AS) is a long-term disease that affects the joints near the center of the body, especially the spine and sacroiliac joints. The sacroiliac joints are located at the lowest end of the spine where the sacrum meets the iliac bone in the pelvis. AS can lead to eventual fusion of the spine. Peripheral joints away from the spine, such as the hips and knees, may also be involved. AS also frequently involves inflammation at the points where the ligaments and tendons insert into the bones. As it progressively affects the spine, it can cause rigidity of the spine and loss of flexibility. It may also involve the hips, knees, and occasionally the small joints of the feet. Inflammation of the connective tissue of the undersurface of the foot (plantar fasciitis) may also occur. Nonskeletal problems associated with AS may include inflammation of the iris or uvea (the colored portion of the eye), and less commonly inflammation of the aorta, scarring of the lungs (pulmonary fibrosis), amyloidosis (excess deposition of an abnormal protein in organs and tissues), and inflammatory bowel disease. Neurological complications include C1-C2 subluxation (partial displacement of the first and second cervical vertebrae), a tendency for spinal fractures with minor trauma, spinal stenosis (narrowing) in the cervical (neck) or lumbar (low back) regions, chronic inflammatory cauda equina (compression of the low back nerve roots that causes paralysis and cuts off sensation to the legs), and radiculopathy (shooting pain caused by pressure on the nerves) secondary to fracture or compression of the nerve roots. AS is more common in males than in females. The male-to-female ratio is approximately 3:1. The peak onset is in adolescents and young adults 15-30 years of age.