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Findings: AP and lateral view of the lumbosacral spine demonstrate flowing osteophytes with bony bridges between the margins of adjacent vertebral bodies seen laterally at all the visualized levels. In addition on the lateral view there is anterior syndesmophyte formation with straightening of the normal curvature of the lumbar spine. Vertebral body height is maintained and there is squaring of the anterior vertebral margins. In addition, ankylosis of the posterior diarthrodial joints. The sacroiliac joints are fused bilaterally. The lateral view of the cervical spine demonstrates similar findings in that there is loss of the normal curvature of the cervical spine with anterior syndesmophyte formation. In addition there is squaring of the vertebral bodies in this region also with virtual complete ankylosis of the diarthrodial joints posteriorly throughout the visualized portions of the cervical spine. There is also a suggestion of atlantoaxial subluxation.

Diagnosis: Ankylosing Spondylitis

Discussion: Ankylosing spondylitis which is a chronic inflammatory disease primarily affecting the spine. It is characterized by involvement of the sacroiliac joints, the spinal apophyseal joints, and the paravertebral soft tissues. Age of onset is usually late in the second decade or early in the third decade of life and approximately (90%) of the patients are male. The patients present with back pain or hip pain. Aortic insufficiency and cardiac conduction disturbances develop in about (4% to 10%) of the cases. Almost all patients are positive for HLA/B27 antigen. The blood rheumatoid factor is characteristically negative. The disease may arrest at any stage. In some patients, progressive spinal rigidity and kyphosis lead to extreme disability as in this individual. The sacroiliac joints are almost invariably affected bilaterally and symmetrically. Pathologically the morphologic features of the proliferative chronic synovitis involving the diarthrodial joints are indistinguishable from those seen in rheumatoid arthritis. In the paraspinal area the formation of bony bridges between the adjacent bodies or syndesmophyte are characteristic as in this case. Radiologically the changes in the spine consist of arthritis of the apophyseal joints, osteitis of the vertebral bodies, syndesmophyte formation, disc degeneration, erosions, kyphosis, subluxations, ankylosis, osteoporosis, pathologic fractures, and vertebral destructive lesions. The process begins in the lumbar region. The end result of the changes in the spine is what is known characteristically as a bamboo spine with universal syndesmophytosis. Posterior interspinous ligament ossification fuses the spinous processes and is seen on frontal projections as a solid midline linear vertical density. Intervertebral disc narrowing accompanies posterior ankylosis. The spine becomes straightened and may develop extreme kyphosis. Subluxations rarely at the atlantoaxial joint may occur as in rheumatoid arthritis with similar serious potential. When the disease begins in adolescence or earlier it is referred to as juvenile ankylosing spondylitis, the mean age group in these individuals being ten to twelve years of age.

References:

Greenfield: Radiology of Bone Diseases, Fourth Edition, 1986 800-810.

Dahnert: Radiology Review Manual, Second Edition, 1991 pg 27.

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