Ankylosing Spondylitis a chronic inflammatory rheumatic disease
Ankylosing spondylitis is part of a group of diseases called seronegative sponsiloarthritis.
The blood tests indicate the absence of rheumatoid factor yet the patients still display strong symptoms of rheumatoid arthritis such as fatigue, fever, weight loss, stiffness of the joints, joint tenderness, joint pain, joint swelling, joint redness, joint warmth, numbness and tingling, decrease in range of body motion etc.
The rheumatoid factor is a protein made by the immune system that can attack healthy tissues in the body, in other words it is an autoantibody.
Ankylosing spondylitis is a chronic and usually progressive inflammatory disease involving the joints of the spine and the adjacent soft tissues. The sacroiliac joints are always affected.
The origin of the name comes from the greek words sphondylos = vertebra and ankýlōsis = ankylosed, deformed.
A short anatomy recap of the vertebral column which consists of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar followed by the sacrum (5 fused sacral vertebrae) and the coccyx (4 fused coccygeal vertebrae).
The prevalence of ankylosing spondylitis in the general population is believed to be between 0.5 and 1% with 1.3-1.6 million cases in Europe, 2.5 and 2.7 million in the USA, 4.6-4.9 million in Asia. The male to female ratio is 2 to 1.
80% of the patients experience symptoms for the first time before the age of 30 and only 5% after the age of 45.
The pathogenesis of ankylosing spondylitis still requires a lot of research. Medical evidence so far seems to include the following factors: genetic - human leukocyte antigen B27 HLA-B27 gene involvement in 85% of patients), environmental (intestinal microorganisms such as Klebsiella), autoimmunity: the involvement of the local tumor necrosis factor alpha (TNF alpha), autoantigens (proteoglycans from cartilage that have a similar structure to the aorta and uvea).
Human leukocyte antigen B27 gene is a protein located on the surface of the white blood cells which helps identify the difference between healthy body tissue and foreign substances. Tumor necrosis factor alpha is a cell signaling protein involved in the systemic inflammation. Proteoglycans are proteins that are heavily glycosylated (addition of carbohydrates) involved in the body defence mechanism.
Pathological changes in ankylosing spondylitis
Pathological changes include inflammation of the spine and sacroilliac joint. Inflammation of the sacroilliac joint is called sacroiliitis. Changes in the spine joints include non-synovial and synovial.
Non-synovial inflammation of the intervertebral spaces has the following effects: vertebral body squaring, syndesmophyte (bony growth inside a ligament leading to the fusion of vertebrae) and calcification of the intervertebral ligaments. Synovial inflammation is apophyseal (natural protrusion forming part of a bone) and costo-vertebral.
Ankylosing spondylitis associated conditions
Ankylosing spondilitis is associated with enthesitis in multiple places. Enthesitis is the inflammation of the entheses, the sites where tendons and ligaments insert into the bone.
Extra-articular manifestations include the eyes (anterior uveitis), heart (aortic regurgitation), large bowel, lung, nervous system and kidney.
The onset of the disease is usually gradual, between the age of 15 to 40, rarely after 50 years. The earliest symptom is low back pain and/or stiffness, which lasts longer than 3 months. The pain is often worse in the early morning and may resemble sciatica (compression of a spinal nerve root in the lower back).
50% of patients develop asymetric oligoarthritis (arthritis affecting two to four joints) targeting the hips, ankles, shoulders, wrists and the small joints of the hands or feet.
As the disease progresses the following changes can take place: intensification of the pain, extension to the lumbar, thoracic and cervical spine, prolonged stiffness, fading of the physiological lumbar lordosis (inward curving of the lumbar spine), paravertebral muscle contraction and increased sensitivity of sacroiliac joints at compression.
The limitation of the spine motility is shown by the increased distance between fingers and soil when bending, Schober test (physical examination to measure the ability of a patient to flex the lower back) and reduction of the lateral motility of the spine.
The limitation of the thoracic spine motility is expressed by the decreased chest expansion (less than 5cm in ankylosing spondilitis compared to the normal value of 5-12cm).
The limitation of the cervical spine motility is determined by measuring extension, right and left rotation, lateral flexion and forward flexion such as the distance between the back of the head and wall.
Clinical findings include tenderness over the sacroiliac joints, costo-sternal joints, spinous processes, iliac crests, ischial tuberosities and heels.
During the advances stage of Ankylosing spondilitis, the following changes can take place: deformities (usually after 10 years), rigidity of the spine, kyphosis (excessive outward curving of the spine) anteflexion of the neck, coxitis (inflammation of the hip joint), joint ankyloses and invalidity.
The therapeutic targets are: manage the pain, decrease the intensity of the inflammatory response, keep spine motility and prevent ankylosis.
Ankylosing spondilitis - methods of therapy
Lifestyle changes for patients with Ankylosing spondilitis include a diet rich in vitamins, low sodium intake, physical activity (gymnastics and sports such as swimming), resting on a hard bed, medical gym and respiration exercises.
From the list of medication prescribed non steroidal antiinflammatory drugs (NSAIDs) are the first line of drugs. These include non-selective (Indomatacin, Diclofenac, Piroxicam), COX2-selective (Meloxicam) and COX2-specific (Celecoxib, Etoricoxib).
In the cases when NSAIDs fail, anti-TNF alpha agents are used in the treatment of Ankylosing spondilitis:
- Enbrel (Etanercept)
In the cases when NSAIDs fail and anti-TNF alpha are contraindicated, slow acting anti-rheumatic drugs (Sulfasalazine, Methotrexate) have a moderate effect on peripheral arthritis.
Glucocorticoids have a poor effect if administered orally. In severe cases, pulse therapy with Methylprednjsolone has proven to have a good effect. Pulse therapy is a way of intensively administering medication at intervals such as weekly or monthly. Routes of administration can be intraarticular or intraocular (in iritis).
Surgery for Ankylosing spondilitis involves joint reconstruction or joint replacement.