Continuing Medical Education: Spondyloarthropathies.

Edited By: Gregory C. Gardner, M.D.
Last updated Friday, January 07, 2005

Ankylosing spondylitis

What is AS?

Pathology

Clinical features

1. Axial Skeleton

   The symptoms of AS are typically insidious in nature. Patients complain of morning low back stiffness lasting 30 minutes to several hours. Pain and stiffness at night and with prolonged sitting is also characteristic. The discomfort is felt in the low back and buttock area and is improved with exercise. If the disease progresses, immobility occurs due to fibrosis and ossification of enthesis about the spine. The entire spine may be affected and in severe cases, patients may develop the so called "bamboo spine". The insertions of the ribs into the spine and intercostal enthesis can also be affected leading to pleuritic-like chest pain with deep breathing and with time fibrosis of these attachments may cause decreased inspiratory excursion of the chest. Sacroiliac joints are usually involved symmetrically but one side may be more involved than another. Sternoclavicular and tempromandibular joints can also be affected.

   Spinal mobility can be measured by the Schober test done by drawing a 10 cm line up from the midposterior iliac spines (the "dimples"). Have the patient bend forward and measure the distraction. Normal is greater than five cm.

2. Peripheral Joints

   AS can also affect the peripheral joints in particular the hips, the shoulders, and the ankles. Overall, 35 percent of patients may have peripheral joint manifestations. This is said to occur more frequently in females. Peripheral joint disease is usually asymmetric.

3. Enthesopathy

   The Achilles tendon and the plantar fascia are frequently affected causing considerable discomfort. The Achilles tendon may be quite swollen and tenderness and is usually at the insertion into the calcaneous. Dactylitis (diffuse swelling of the fingers or toes also called sausage digits) may also be present representing diffuse enthopathy.

4. Eye Disease

   As many as 25 percent of patients with AS may have this manifestation during the course of their illness. Anterior uveitis or iritis is typically episodic and unilateral. Blindness is rare but the uveitis may be severe enough to require local or even systemic corticosteroids. Eye involvement appears to be more common in patients with peripheral joint disease.

5. Cardiovascular Disease

   This complication usually occurs in patient with long standing severe AS with peripheral joint involvement. Aortic incompetence may be a combination of aortic valve cusp fibrosis and or aortitis distal to the valve itself. Complete atrioventricular block with Stokes-Adams attacks may occur. Cardiac involvement is found in up to 10 percent of patients after 10 years of disease.

6. Pulmonary Disease

   Patients with severe spondylitis may develop upper lobe fibrosis. Cysts formation may occur and these may be colonized by Aspergillus. Patients may succumb to massive hemoptysis. Restrictive lung disease may be present but is normally mild.

7. Important Spinal Complications

   The immobile spine fractures easily with even minor trauma. The most common site is the cervical spine. Most fractures center around C5 and are transverse through the disc space. Gross instability can occur leading to impingement on the cord or vertebral arteries. Fracture may not be apparent on X-ray and may require CT scan or bone scan to localize. This is a true rheumatologic urgency.

   The cauda equina syndrome may cause insidious onset of pain in the buttocks or legs associated with bowel and bladder symptoms. This is due to spinal cord compression at the level of the cauda equina. Myelogram or MRI demonstrate lumbar diverticuli. Therapy, including surgery and high dose steroids, have not been satisfactory.

   Spinal stenosis can also occur due to bone over growth and nerve impingement. This may respond favorably to surgery.

   Spondylodiscitis occurs at a vertebral disc space (usually in the thoracic spine) that has become mobile. It is a source of mechanical-type back pain and although not usually unstable, can be a source of significant pain. On X-ray, there is usually erosion of the vertebral end plates and may mimic an infectious process. Treatment is by surgical fusion or trial of bracing to allow the segment to refuse on its own.

Radiographic features

1. Sacroilitis

   Initial changes include blurring of the joint margins and reactive sclerosis. With progression there may be complete fusion of the joints. Bilateral sacroilitis occurs in AS. Early changes at the sacroiliac joints are nicely demonstrated by CT scan.

2. Syndesmophytes

   These occur from ossification of the area of the annulus fibrosus and bridge adjacent vertebrae. With advancing disease, these can give the spine a bamboo appearance.

3. Vertebral Squaring

   Erosions at the vertebrae occur first at the anterosuperior anteroinferior corners. This leads to the appearance of squaring.

4. Reactive Sclerosis

   The anterior edges of the vertebrae can develop reactive sclerosis and have a so-called "shining corner" appearance. Reactive sclerosis/"fluffy" periostitis can also develop at the symphysis pubis and the ischium.

5. Calcaneal Spurs/Erosions

   Erosions can develop around the Achilles tendon insertion and calcaneal spurs are also common. Periostitis can occur at the calcaneus giving a "fluffy" appearance to the heel.

Treatment

1. Education

   Patients need to know the nature of their illness and its treatment. An extensive discussion is important for those who are recently diagnosed. There are educational materials available through the Arthritis Foundation, the Spondylitis Association of America, and on this web site.

2. Physical Therapy

   All patients should be sent to see a physical therapist when diagnosed to learn techniques for good posture and daily stretching. Patients should be encouraged to stay active! Swimming is an excellent activity for patients with arthritis.

3. Medication
   • NSAIDs are the mainstay of treatment. Patients usually have very immediate relief. Indomethicin or phenylbutazone (now under restricted use) are felt to be the most effective but most NSAIDs will work. Patients on these medication long term need to be monitored on a regular schedule (at one month then every three to twelve months thereafter).
   • Corticosteroids are useful for intra-articular use for peripheral joints but are not felt to be effective for spinal disease.
   • Sulfasalizine has recently been found useful for both the peripheral joint involvement but also shows promise in the spinal disease as well.
   • Other medications: Methotrexate is used by many rheumatologists but there are few studies. Of historic interest is the use of radiation which apparently did wonders for the spinal disease but lead to high a incidence of leukemia.
4. Surgery

   There is a limited role for surgery except in patients with severe hip or shoulder disease. A neurosurgeon or orthopaedic spine surgeon should be consulted early for spine fractures, cauda equina syndrome or spondylodiscitis.

Prognosis

Surgery for arthritis at the University of Washington

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