Spondyloarthropathy--AS

 

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Original Editors - Adam Bockey from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

 Spondyloarthropathy represents a group of noninfectious, inflammatory, rheumatic diseases that primarily includes ankylosing spondylitis, Reiter’s syndrome, reactive arthritis, and the arthritis associated with psoriasis and inflammatory bowel diseases. The primary pathologic sites are the sacroiliac joints, the bony insertions of the annulus fibrosi of the intervertebral discs, and the apophyseal joints of the spine. 
Ankylosing Spondylitis (AS) also known as Marie- Strumpell disease or bamboo spine, is an inflammatory arthropathy of the axial skeleton, usually involving the sacroiliac joints, apophyseal joints, costovertebral joints, and intervertebral disc articulations. AS is a chronic progressing inflammatory disease that causes inflammation of the spinal joints that can lead to severe, chronic pain and discomfort. In advanced stages, the inflammation can lead to new bone formation of the spine, causing the spine to fuse in a fixed position often creating a forward stooped posture.

Prevalence

 Ankylosing Spondylitis is 3 times more common in men than in women and most often begins between the ages of 20-40. Recent studies have shown that AS may be just as prevalent in women, but diagnosed less often because of a milder disease course with fewer spinal problems and more involvement of joints such as the knees and ankles. Prevalance of AS is nearly 2 million people or 0.1% to 0.2% of the general population in the United States. It occurs more often in Caucasions and some Native American than in African Americans, Asians, or other nonwhite groups. AS is 10 to 20 times more common with first degree relatives of AS patients than in the general population. The risk of AS in first degree relatives with the HLA-B27 allele is about 20% occurrence.

Characteristics/Clinical Presentation 

The initial presenting complaints of AS is non-traumatic, insidious onset of low back, buttock, or hip pain and stiffness for more than 3 months in a person, usually male under 40 years of age. It is usually worse in the morning lasting more than 1 hour and is described as a dull ache that is poorly localized, but it can be intermittently sharp or jolting. Overtime pain can become severe and constant and coughing, sneezing, and twisting motions may worsen the pain. Pain may radiate to the thighs, but does not typically go below the knee. Buttock pain is often unilateral, but may alternate from side to side. Paravertebral muscle spasm, aching, and stiffness are common making sacrioliac areas and spinous process very tender upon palpation. A flexed posture eases the back pain and paraspinal muscle spasm; therefore, kyphosis is common in untreated patients. Enthesitis (inflammation of tendons, ligaments, and capsular attachments to bone) may cause pain or stiffness and restriction of mobility in the axial skeleton. A positive Schober test is used to confirm reduction in spinal motion which is associated with AS. Since AS is a systemic disease an intermittent low grade fever, fatigue, or weight loss can occur. In advanced stages the spine can become fused and a loss of normal lordosis with accompanying increased kyphosis of the thoracic spine, painful limitations of cervical joint motion, and loss of spine flexibility in all planes of motion. A decrease in chest wall excursion less than 2 cm could be an indicator of AS because chest wall excursion is an indicator of decreased axial skeleton mobility. 

Associated Co-Morbidities

Uveitis, conjunctivitis, or iritis occurs in nearly 25% of the people with AS. Signs of iritis or uveitis are: eye(s) becoming painful, watery, red, and sometimes blurred vision or sensitivity to bright light. Pulmonary changes such as chronic infiltrative or fibrotic bullous changes of the upper lobe occur in 1% to 3% of the people with AS. Cardiomegaly, conduction defects, and pericarditis are all common complications of AS. Also many people with AS experience bowel inflammation, which can be associated with Crohn’s Disease or ulcerative colitis.  

Medications

 NSAIDs (nonsteroidal anti-inflammatory drugs) reduce pain and suppress joint inflammation and muscle spasm, in return increasing range of motion. NSAIDs can cause significant side effects, in particular, damage to the gastrointestinal tract. In some cases disease modifying anti-rheumatic drugs (DMARDS) such as methotrexate (MTX) or sulfasalazine (SSZ) may be used for peripheral disease. Corticosteroid injections into the sacroiliac joints may help severe sacroiliitis. Topical corticosteroids can also be used for acute uveitis or iritis. The most recent medication for AS are the biologics or TNF Blockers. These agents have been shown effective in preventing the progression of AS by reducing disease activity, decreasing inflammation, and improving spinal mobility.
Examples of TNF blockers include:
 Adalimumab (Humira)
 Etanercept (Enbrel)
 Infliximab (Remicade)
 Golimumab (Simponi)

Diagnostic Tests/Lab Tests/Lab Values

Diagnostic Tests/Lab Tests/Lab Values

AS can be diagnosed by the modified New York criteria, the patient must have radiographic evidence of sacroiliitis and one of the following: (1) restriction of the lumbar spine motion in both the sagittal and frontal planes, (2) restriction of chest expansion (usually < 2.5 cm) (3) a history of back pain includes onset at <40 year, gradual onset, morning stiffness, improvement with activity, and duration >3 months.  

Imaging tests 5
 X-rays. Radiographic findsing of symmetric, bilateral sacroiliitis include blurring of joint margins, juxtaarticular sclerosis, erosion, and joint space narrowing. As bony tissue bridges the vertebral bodies and posterior arches, the lumbar and thoracic spine creates a “bamboo spine” image on radiographs.2
 Computerized tomography (CT). CT scans combine X-ray views taken from many different angles into a cross-sectional image of internal structures. CT scans provide more detail, and more radiation exposure, than do plain X-rays.5
 Magnetic resonance imaging (MRI). Intraarticular inflammation, early cartilage changes and underlying bone marrow edema and osteitis can be seen using an MRI technique called short tau inversion recovery (STIR).2 Using radio waves and a strong magnetic field, MRI scans are better at visualizing soft tissues such as cartilage.5
Lab tests. There is no current laboratory testing in the diagnostic of AS, laboratory tests are primarily for ruling out other diseases. The presence of the HLA-B27 antigen is a useful adjunct to the diagnosis, but cannot be diagnostic alone.2

Etiology/Causes

 AS is believed to be genetically inherited, and nearly 90% of people with AS are HLA-B27 positive.6 However, only 2% of the people with this antigen develop AS.2 Additionally, 10% to 20% of people who have a first degree relative with AS and how inherit the HLA-B27 antigen eventually develop AS. 7 Recently, two more genes have been identified that are associated with AS. These genes, ARTS1 and IL23R, seem to play a role in influencing immune function.6 The IL23R gene plays a role in the immune response to infection and making a receptor present on the surface of several types of immune system cells. The receptor is involved in triggering certain chemical signals inside the cell that promote inflammation and help coordinate the immune system's response to infection. It is already recognized as playing a role in a number of autoimmune diseases, such as Crohn's disease and psoriasis, which often are associated Co-morbidities.8

Systemic Involvement

-Neurologic involvement - Symptoms associated with spinal dislocations, subluxations, fractures, cauda equina syndrome
- Cardiovascular manifestations - Aortitis, aortic/mitral insufficiency, conduction defects
- Hip/shoulder involvement
- Chronic back stiffness and pain

Medical Management (current best evidence)

The primary medical focus with AS is to reduce inflammation and stiffness in the joints, maintain mobility and correct posture alignment, while relieving pain. NSAIDS or DMARDs are the most commonly medications used for joint pain and inflammation. For more progressive forms of AS surgery may be indicated; however, this may only be appropriate for individuals with sever deformities that impedes vision, ambulating, eating, chest excursion, or respiratory function. Other targeted therapies may be indicated to treat specific organ involvement, such as eye inflammation to avoid lifelong complications.

Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Resources

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Recent Related Research (from Pubmed)

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References

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