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Ankylosing spondylitis (AS; also known as Bechterew's disease; Bechterew syndrome; Marie Strümpell disease / Marie Struempell disease / Spondyloarthritis) is a chronic, painful, degenerative inflammatory arthritis primarily affecting spine and sacroiliac joints, causing eventual fusion of the spine; it is a member of the group of the autoimmune spondyloarthropathies with a probable genetic predisposition. Complete fusion results in a complete rigidity of the spine, a condition known as bamboo spine. Signs and symptoms The typical patient is young, of 15 to 30 years of age with chronic pain and stiffness in the lower part of the spine. Men are affected more than women by a ratio in excess of 2:1. In 40% of cases, ankylosing spondylitis is associated with iridocyclitis (anterior uveitis, also known as iritis) causing eye pain and photophobia (increased sensitivity to light). Other common symptoms are recurring mouth ulcers (aphthae) and fatigue. Pain fluctuation from one side to the other. Typical prodromes (early symptoms) may occur at a very young age (e.g. 3 years old), where the patient may experience recurring painful joints (e.g. knees, elbows), commonly misinterpreted as simple rheumatism. AS is also associated with ulcerative colitis, Crohn's disease, psoriasis, and Reiter's disease.
Diagnosis 
The ankylosis process. There is no direct test to diagnose AS. A clinical examination and X-ray studies of the spine, which show characteristic spinal changes and sacroiliitis, are the major diagnostic tools. A drawback of X-ray diagnosis is that signs and symptoms of AS have usually been established as long as 8-10 years prior to X-ray evident changes occurring on a plain film X-ray, which means a delay of as long as 10 years before adequate therapies can be introduced. An option for more accurate (and much earlier) diagnosis are tomography and magnetic resonance imaging of the sacroiliac joints. The Schober's test is a useful clinical measure of flexion of the lumbar spine performed during examination. During acute inflammatory periods, AS patients will usually show an increase in the blood concentration of C-reactive protein (CRP) and an increase in the erythrocyte sedimentation rate (ESR). Variations of the HLA-B gene increase the risk of developing ankylosing spondylitis, although it is not a diagnostic test. Those with the HLA-B27 variant are at highest risk of developing the disorder. HLA-B27, demonstrated in a blood test, is occasionally used as a diagnostic, but does not distinguish AS from other diseases and is therefore not of real diagnostic value. Over 95% of people with AS are HLA-B27 positive, although this ratio varies from population to population (only 50% of African American patients with AS possess HLA-B27, and it is close to 80% among AS patients from Mediterranean countries). The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), developed in Bath (UK), is an index designed to detect the inflammatory burden of active disease. The BASDA can help to establish a diagnosis of AS in the presence of other factors such as HLA-B27 positivity, persistent buttock pain which resolves with exercise, and X-ray or MRI evident involvement of the sacroiliac joints. (See: "Diagnostic Tools", below)[4] It can be easily calculated and accurately assesses a patient's need for additional therapy; a score of 4 out of a possible 10 points while on adequate NSAID therapy is usually considered a good candidate for biologic therapy. The Bath Ankylosing Spondylitis Functional Index (BASFI) is a functional index which can accurately assess a patient's functional impairment due to the disease, as well as improvements following therapy. (See: "Diagnostic Tools", below)[5] The BASFI is not usually used as a diagnostic tool, but as a tool to establish a patient's current baseline and subsequent response to therapy.
Pathophysiology AS is a systemic rheumatic disease, and is one of the seronegative spondyloarthropathies. About 90% of the patients express the HLA-B27 genotype. Tumor necrosis factor-alpha (TNF α) and IL-1 are also implicated in ankylosing spondylitis. Although specific autoantibodies cannot be detected, its response to immunosuppresive medication has prompted its classification as an autoimmune disease. Hypotheses on its pathogenesis include a cross-reaction with antigens of the Klebsiella bacterial strain (Tiwana et al. 2001).[6] Particular authorities argue that elimination of the prime nutrients of Klebsiella (starches) would decrease antigenemia and improve the musculoskeletal symptoms. On the other hand, Khan (2002) argues that the evidence for a correlation between Klebsiella and AS is circumstantial so far, and that the efficacy of low-starch diets has not yet been scientifically evaluated. Similarly, Toivanen (1999) found no support for the role of klebsiella in the etiology of primary AS.
Epidemiology The sex ratio is 3:1 for men:women. In the USA, the prevalence is 0.25%, but as it is a chronic condition the incidence (number of new cases) is fairly low.
History 
Leonard Trask, the Wonderful Invalid. AS was probably first recognized as a disease which was different from Rheumatoid Arthritis by Galen as early as the second century AD; however, skeletal evidence of the disease (ossification of joints and entheses primarily of the axial skeleton, known as "bamboo spine") were first discovered in an archaeological dig that unearthed the skeletal remains of a 5000 year-old Egyptian mummy with evidence of "bamboo spine". The anatomist and surgeon Realdo Colombo described what could have been the disease in 1559,[11] and the first account of pathologic changes to the skeleton possibly associated with AS was published in 1691 by Bernard Connor.[12] In 1818, Benjamin Brodie became the first physician to document that iritis accompanied what is believed to have been a patient with active AS.[13] In 1858, David Tucker published a small booklet which clearly described a patient by the name of Leonard Trask who suffered from severe spinal deformity subsequent to AS. In 1833 Trask fell from a horse, exacerbating the condition and resulting in severe deformity. Tucker reported that | " | It was not until he [Trask] had exercised for some time that he could perform any labor [..., and that] his neck and back have continued to curve drawing his head downward on his breast. | " |
evidence of inflammatory disease characteristics of AS, and the hallmark of deforming injury in AS. This account became the first documented case of AS in the United States. It was not until the late nineteenth century (1893-1898), however, when the neurophysiologist Vladimir Bekhterev of Russia in 1893. Adolph Strümpell of Germany in 1897,and Pierre Marie of France in 1898, were the first to give adequate descriptions which permitted an accurate diagnosis of AS prior to severe spinal deformity. For this reason, AS is also known as Bechterew Disease or Marie-Strümpel Disease.
Prognosis AS can range from mild to progressively debilitating, and from medically controlled to refractive. Unattended cases of AS normally lead to knee pain, and may be accompanied by dactylitis or enthesitis, which may result in a misdiagnosis of normal rheumatism. In a long-term undiagnosed period, osteopenia or osteoporosis of AP spine may occur, causing eventual compression fractures and a back "hump" if untreated. Typical signs of progressed AS are the visible formation of syndesmophytes on X-rays, an abnormal bone outgrowth similar to osteophytes, affecting the spine. Due to the fusion of the vertrbrae paresthesia is a complication due to the inflammation of the tissue surrounding nerves. Organs affected by AS, other than the axial spine and other joints, are commonly the heart, lungs, colon, and kidney. Other complications are Aortic regurgitation[citation needed], Achilles tendinitis, AV node block[citation needed] and Amyloidosis[citation needed]. Due to lung fibrosis[citation needed], chest X-rays may show apical fibrosis while pulmonary function testing may reveal a restrictive lung defect. Very rare complications involve neurologic conditions such as the cauda equina syndrome.
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