Ankylosing spondylitis

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Initial posting by: Jonathan Stone

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Ankylosing spondylitis (AS; also known as Bechterew's disease; Marie Strümpell 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.

Ankylosing Spondylitis - Ossification of the annulus fibrosus in the lumbar spine has resulted in the formation of marginal syndesmophytes in a gradually ascending pattern ("bamboo spine").[
  • [#Signs_and_symptoms 1 Signs and symptoms]
  • [#Diagnosis 2 Diagnosis]
  • [#Pathophysiology 3 Pathophysiology]
  • [#Epidemiology 4 Epidemiology]
  • [#Treatment 5 Treatment]
    • [#Medication 5.1 Medication]
    • [#Surgery 5.2 Surgery]
    • [#Physical_therapy 5.3 Physical therapy]
  • [#Prognosis 6 Prognosis]
  • [#References 7 References]
  • [#External_links 8 External links]
    • [#National_organizations 8.1 National organizations]
    • [#Diagnostic_tools 8.2 Diagnostic tools]
    • [#Support_groups 8.3 Support groups]
    • [#Current_research 8.4 Current research]

Signs and symptoms

AS typically presents with back pain, characterized by inflammation of the axial skeleton and large peripheral joints. There is often compression radiculitis, vertebral fracture or subluxation and cauda equina syndrome. 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.

Typical prodromes 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.


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 CT and MRI scans of the sacroiliac joints. The Schober test is a useful clinical measure of flexion of the lumber spine performed during examination. Characteristic kyphosis always seen with bamboo spine due to paraspinal ligament calcification and calcification at the vertebral body/disc interface.

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, Somerset (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.2 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.3 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.

AS must be differentiated from DISH syndrome (Diffuse Idiopathic Skeletal Hyperostosis) which may also present with spinal pain, stiffness, and insidious loss of spine motion but sacroiliac and spinal apophyseal joints are not involved and there is no link with HLA-B27.


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.4 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.5 Similarly, Toivanen (1999) found no support for the role of klebsiella in the etiology of primary AS.6


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 2:1 over women.1 In the USA, the prevalence is 0.25%, but as it is a chronic condition the incidence is fairly low.


No cure is known for AS, although treatments and medications are available to reduce symptoms and pain.

Physical therapy and exercise, along with medication, are at the heart of therapy for ankylosing spondylitis. Physiotherapy and physical exercises are clearly preceded by medical treatment in order to reduce the inflammation and pain, and commonly followed by a physician. This way the movements will help in diminishing pain and stiffness, while exercises in an active inflammatory state will just make the pain worse.

Patients who are able to do so, lie flat on their face or back on the floor for a prescribed cumulative period of time each week, to prevent the chronic stooping which may otherwise result.9


There are three major types of medications used to treat ankylosing spondylitis.

TNFα blockers have been shown to be the best promising treatment, slowing the progress of AS in the majority of clinical cases. They have also been shown to be highly effective in treating not only the arthritis of the joints but the spinal arthritis associated with AS. A drawback is the fact that these drugs increase the risk of infections. For this reason, the protocol for any of the TNF-α blockers include a test for tubercolosis (like Mantoux or Heaf) before starting treatment. In case of recurrent infections, like recurrent pharyngitis, the therapy may be suspended due to the involved immunosuppression.


In severe cases of AS, surgery can be an option in the form of joint replacements, particularly in the knees and hips. Surgical correction is also possible for those with severe flexion deformities (severe downward curvature) of the spine, particularly in the neck, although this procedure is considered risky.

In addition, AS can have some manifestations which make anaesthesia more complex.

Changes in the upper airway can lead to difficulties in intubating the airway, spinal and epidural anaesthesia may be difficult due to calicification of ligaments, and a small number have aortoc insufficiency. The stiffness of the thoracic ribs results in ventilation being mainly diaphragm-driven, so there may be a decrease in pulmonary function.

Physical therapy

All physical therapies must be approved in advance by a rheumatologist, since movements that normally have great benefits on one's health, may harm a patient with AS: massages and physical manipulations should be practiced by therapists familiar with this disease.

  • Physical therapy has been shown to be of great benefit to AS patients.
  • Swimming is one of the preferred exercises since it involves all muscles and joints in a low gravity environment.
  • Slow movements exercises like stretching, yoga, tai chi;
  • Any physical movement like, jogging, Pilates method, etc.


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, achilles tendonitis, AV node block and amyloidosis. Due to lung fibrosis, 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.7 The cauda equina syndrome involves dorsal and ventral roots (classically L3-S5) and usually involves just lower motor neurons.


  1. Spodylitis Association of America
  2. Garrett S, Jenkinson T, Kennedy L, Whitelock H, Gaisford P, Calin A (1994). "A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index.". J Rheumatol 21 (12): 2286-91. PMID 7699630.
  3. Calin A, Garrett S, Whitelock H, Kennedy L, O'Hea J, Mallorie P, Jenkinson T (1994). "A new approach to defining functional ability in ankylosing spondylitis: the development of the Bath Ankylosing Spondylitis Functional Index.". J Rheumatol 21 (12): 2281-5. PMID 7699629.
  4. Tiwana H, Natt R, Benitez-Brito R, Shah S, Wilson C, Bridger S, Harbord M, Sarner M, Ebringer A (2001). "Correlation between the immune responses to collagens type I, III, IV and V and Klebsiella pneumoniae in patients with Crohn's disease and ankylosing spondylitis.". Rheumatology (Oxford) 40 (1): 15-23. PMID 11157137.
  5. Khan MA. (2002). Ankylosing spondylitis: The facts. Oxford University Press. [/wiki/index.php?title=Special:Booksources&isbn=0192632825 ISBN 0-19-263282-5].
  6. Toivanen P, Hansen D, Mestre F, Lehtonen L, Vaahtovuo J, Vehma M, Möttönen T, Saario R, Luukkainen R, Nissilä M (1999). "Somatic serogroups, capsular types, and species of fecal Klebsiella in patients with ankylosing spondylitis.". J Clin Microbiol 37 (9): 2808-12. PMID 10449457.
  7. Calin A. (1985). "Ankylosing spondilitis.". Clinics in Rheumatic Diseases 11: 41–60.
  8. Nicholas U. Ahn, Uri M. Ahn, Elizabeth S. Garrett et al. (2001). "Cauda Equina Syndrome in AS (The CES-AS Syndrome): Meta-analysis of outcomes after medical and surgical treatments.". J of Spinal Disorders 14 (5): 427-433. PMID 11586143.
  9. Living with Ankylosing Spondylitis. Retrieved on 2007-01-11.
  10. Ebringer A, Wilson C (Jan 15 1996). "The use of a low starch diet in the treatment of patients suffering from ankylosing spondylitis.". Clin Rheumatol 15 Suppl 1: 62-66. PMID 8835506.

External links

National organizations

Diagnostic tools

Support groups

  • (online community; support and information)
  • [2] Spondylitis Association of America (online information, support community, research]

Current research

Personal tools