Ankylosing Spondylitis, Neurologic Perspective

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.

• About 90-95% of persons with AS have the human leukocyte antigen B27 (HLA-B27) antigen, but not everyone who has that antigen develops AS.



• Presumably, a fairly benign bacterium or virus can be antigenically similar to human ligaments. This speculation is more applicable to spondylitis associated with reactive arthritis (Reiter disease) than AS.



• In a genetically susceptible individual, a mild infection may stimulate an abnormal immune response, causing the development of AS. Again, this speculation is more applicable to spondylitis associated with reactive arthritis (Reiter disease) than AS.

• Low back pain and stiffness gradually increase over 3 or more months. The pain is usually described as follows:
  
  
  • Worse in the morning with improvement during the day
  
  
  
  • Better with activity and worse with inactivity (This finding helps in distinguishing AS from mechanical low back pain.)
  
  
  
  • Gradual ascending pattern from the lumbar region to the thoracic spine and then the cervical spine
     
• Approximately 25% of persons with AS experience proximal joint (hips, knees) involvement. Rarely, persons with AS may complain mostly of small joint (ankles, toes [metatarsophalangeal joints]) involvement. Arm joints are rarely involved.



• Persons with AS may describe pain and stiffness of the rib cage. Breathlessness on exertion may be experienced. In long-standing disease, a small percentage of patients may develop fibrosis (scarring) in the upper lobes of the lungs.

• The HLA-B27 antigen is found in 90-95% of persons with ankylosing spondylitis. However, its presence is not sufficient to make the diagnosis. The test for HLA-B27 is most helpful when the diagnosis is not clear.

• Cerebrospinal fluid protein level may be mildly elevated during acute exacerbations of AS.



• Low-grade anemia (decreased hemoglobin level) may be present.

• Plain x-ray films of the pelvis may show sacroiliitis or, later, fusion of sacroiliac joints.

• Spinal x-ray films of the lumbar region may show changes in the ligaments and fusion of facet joints (bony prominences on the vertebrae that form joints with similar projections on the upper or lower aspect of adjacent vertebrae). The appearance of this fusion gives rise to the term bamboo spine. With extensive fusion of the spine, a person may have what is called a poker spine.

• Spinal CT scan may show bony fusions and eroded laminae and spinous processes (parts of the vertebrae).

• Spinal MRI may be needed to document atlantoaxial (first two cervical vertebrae) subluxation (dislocation). MRI may be indicated after trauma to evaluate the spinal cord and to rule out cauda equina syndrome or epidural hematoma (space between the wall of the spinal canal and the covering of the spinal cord is filled with blood).

• Cauda equina syndrome may be inflammatory or compressive. This may occur late in the disease course.

• In inflammatory cauda equina syndrome, the spinal canal is normal to large with cerebrospinal fluid diverticulae (outpouching) that are best seen on MRI.

• Plain spinal x-ray films or spinal CT scans may be indicated after trauma to evaluate for bony injury.

General principles of treatment include the following:

• Exercise and postural training to strengthen the back and neck and help maintain correct posture



• Medications to decrease pain and inflammation



• Diagnosis and treatment of potential complications



• Smoking cessation

Good sleeping posture with a small pillow on a firm mattress in either the supine (lying face upward) position or the prone (lying face downward) position helps in alleviating pain and stiffness in persons with ankylosing spondylitis.

The goal of drug therapy is to control pain and decrease inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used medications. NSAIDs reduce pain and inflammation. No particular NSAID, such as ibuprofen (Advil, Motrin) or naproxen (Aleve, Naprosyn), has been shown to be clearly superior for treating AS. Sulfasalazine, corticosteroids, and other immunosuppressive agents are also used but are of limited benefit.

Recently, biologic agents have been found to be useful in treating AS. Antibodies to tumor necrosis factor, such as etanercept (Enbrel) and infliximab (Remicade), are now approved to treat AS. These target the disease process and may alter the disease process.

For more information, see Understanding Ankylosing Spondylitis Medications.

Surgical treatment may be necessary for some complications of ankylosing spondylitis.

• Surgical fusion may be required to stabilize atlantoaxial subluxation.

• Cervical spine fractures require rigid immobilization, usually with a halo (a circular metal band used in a halo cast or halo brace that is attached to the skull with pins). In such cases, surgical fusion is usually not required.

• Surgery is rarely indicated for correction of uncomplicated thoracic kyphosis (excessive curvature of the upper part of the spine, resulting in hunchback).

• Thoracolumbar fractures require reduction of displacement and stabilization, usually with rods. Laminectomy (a surgery to remove part of the lamina of the vertebral body) is rarely needed.

• Decompression of cervical or lumbar spinal stenosis is performed when nerves are compressed.



• If weight-bearing joints are involved, hip or knee replacement may be necessary.

• Daily bending, twisting, and gentle range of motion exercises help prevent postural deformities and restriction of joint movement. Stretching exercises minimize the long-term impact of spinal stiffness and restrictions.



• Breathing exercises are recommended to prevent chest wall immobility. Cessation of smoking is also strongly recommended.

• Symptoms of pain and stiffness are common and may be moderately severe to severe. Persons with ankylosing spondylitis have few problems with social interactions, although depression is common.



• Most persons remain employed, and relatively few develop severe functional disability. Disability correlates with the duration of disease, disease activity, and spinal mobility. Peripheral joint involvement also results in greater impairment.

The following Web sites provide support to people with AS and their families and friends:

• Spondylitis Association of America Sponsored Support Groups



• Reiter's Information & Support Group Inc.



• Spondyville

Spondylitis Association of America
PO Box 5872
Sherman Oaks, CA 91413
(800) 777-8189, (818) 981-1616
info@spondylitis.org

The North American Spine Society
22 Calendar Court, 2nd Floor  
LaGrange, IL 60525
(877)-Spine-Dr, (847) 698-1630
info@spine.org

Arthritis Foundation
PO Box 7669
Atlanta, GA 30357-0669
(800) 568-4045

American College of Rheumatology
1800 Century Place, Suite 250
Atlanta, GA 30345-4300
(404) 633-3777

National Institute of Arthritis and Musculoskeletal and Skin Diseases
Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, Maryland 20892-3675
(301) 495-4484 or (877) 22-NIAMS (toll free)

Ankylosing Spondylitis International Federation
6 Falcarragh Road, Gaeltacht Park
Whitehall, Dublin 9, Ireland
(+353-1) 83 76 614
asai@oceanfree.net

|Web Links|

Spondylitis Association of America
 
The Ankylosing Spondylitis International Federation

The Assessment in Ankylosing Spondylitis (ASAS) International Working Group

Arthritis Foundation

Media file 1: Sacroiliitis. Pelvic x-ray film showing erosion of the sacroiliac joints.

Media type:  X-RAY

Media file 2: Vertebral fusion. Cervical x-ray film showing ankylosis of all cervical joints from the second cervical vertebrae downward.

Media type:  X-RAY

Media file 3: Bamboo spine. Lumbar x-ray film showing complete fusion of the lumbar vertebral bodies.

Media type:  X-RAY

ankylosing spondylitis, neurological perspective, ankylosing spondylitis, AS, arthritis, sacroiliac joint, intervertebral joint, fused vertebra, fused spine, spinal stenosis, bamboo spine, rigid spine, low back pain, back stiffness, early-morning stiffness, loss of spine mobility, HLA-B27 antigen, nonsteroidal anti-inflammatory drugs, NSAIDs, sulfasalazine, axial joint, plantar fasciitis, C1-C2 subluxation, spinal fracture, inflammatory cauda equina syndrome, cauda equina syndrome, thoracic kyphosis, radiculopathy, nerve root compression 

Author: Alan Schaffert, MD, Past Chief of Staff, Doctor's Medical Center of Modesto, Clinical Assistant Professor, Department of Medicine, University of California at Davis.

Editors: Kristine M Lohr, MD, Associate Chief, Program Director, Professor, Department of Internal Medicine, Division of Rheumatology, University of Tennessee School of Medicine; Mary L Windle, Pharm D, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, .com, Inc; Nicholas Y Lorenzo, MD, Chief Editor, Neurology; Consulting Staff, Neurology Specialists and Consultants.