Ankylosing Spondylitis, Neurologic Perspective

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Ankylosing Spondylitis, Neurologic Perspective

AS Neurologic Overview

Ankylosing spondylitis (AS) is a long-term disease process that affects the axial joints near the midline, especially the spine and sacroiliac joints (the joints located at the lowest end of the spine, called the sacrum and the pelvis). AS causes eventual fusion of the spine. Peripheral joints, such as the hips and knees, may be involved; the arms are almost never involved.

The primary disease process involves inflammation where the ligaments and tendons insert into the bones. The disorder predominantly affects the bones, causing rigidity of the spine. 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 layer of the eye below the white of the eye), and less commonly inflammation of the aorta, pulmonary fibrosis, amyloidosis (deposition of a complex 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 syndrome (compression of the low back nerve roots, which causes paralysis and cuts off sensation), and radiculopathy (shooting pain caused by pressure on the nerves) secondary to fracture or compression of the nerve roots.

In the general population, 1.4% people are affected with AS. 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 aged 15-30 years.