Ankylosing spondylitis (Strumpel-Marie-Bekhterev’s disease) is a chronic inflammatory ankylosing disease of the joints of the axial skeleton (intervertebral, costovertebral, sacroiliac), belonging to the group of seronegative spondyloarthritis. The disease occurs with a frequency of 2:1000 of the population, and men get sick 3-4 times more often than women.
The cause of the disease is unknown. Of great importance is hereditary predisposition, the genetic marker of which is the HLA B27 antigen, which occurs in 90-95% of patients, in 20-30% of their first-degree relatives, and only in 7-8% in the population. It is believed that the gene for sensitivity to ankylosing spondylitis is linked to the HLA B27 gene.
There are two theories of pathogenesis explaining the important role of HLA B27 in the development of ankylosing spondylitis. According to the receptor theory, the HLA B27 antigen is a receptor for an etiological damaging factor (for example, a bacterial antigen, a virus, an arthritogenic peptide, etc.). The resulting complex leads to the production of cytotoxic T-lymphocytes, which can then damage cells or tissue areas where the B27 antigen molecules are located.
According to the theory of molecular mimicry, a bacterial antigen or some other damaging agent in combination with another HLA molecule can have properties similar to HLA B27 and be recognized by cytotoxic T-lymphocytes as HLA B27 or reduce the immune response to the disease-causing peptide (immune tolerance phenomenon).
As a result, an immunoinflammatory process develops. More often it begins with the defeat of the sacroiliac joints, then the intervertebral, costovertebral, less often peripheral joints are involved. First, infiltration by lymphocytes and macrophages occurs, then an active fibroplastic process develops with the formation of fibrous scar tissue, which undergoes calcification and ossification.
The main pathomorphological manifestations of Bechterew’s disease are inflammatory enthesopathy (inflammation of the places of attachment to the bone of tendons, ligaments, the fibrous part of the intervertebral discs, joint capsules), inflammation of the bones that form the joint (osteitis), and synovitis.
Subsequently, fibrous and bone ankylosis of the joints of the axial skeleton develops, less often – peripheral joints, ossification of the ligamentous apparatus of the spine occurs early.
The disease usually begins before the age of 40 and is more common in men.
Early stage symptoms
- Pain in the lumbar spine and in the region of the sacroiliac joints of a permanent nature, aggravated mainly in the second half of the night and in the morning, decreasing with movements and in the afternoon (inflammatory “character” of pain).
- Pain in the gluteal region due to damage to the sacroiliac joints with irradiation to the back of the thigh, which occurs either on the right or on the left.
- Feeling of stiffness and stiffness in the lumbar spine, usually worse in the morning and better after exercise, hot showers.
- Pain in the chest (when the costovertebral joints are involved in the pathological process) by the type of intercostal neuralgia or myositis of the intercostal muscles, aggravated by coughing, sneezing, deep inspiration.
- Stiffness and tension of the rectus muscles of the back.
- Flattening of the lumbar lordosis (especially noticeable when the patient is tilted forward).
- Clinical and radiological symptoms of bilateral sacroiliitis; to detect pain in the sacroiliac joints, indicating the presence of an inflammatory process in them, the following tests are used:
– Makarov’s test (effleurage on the sacrum);
– Kushelevsky-1 test (pressure on the upper anterior iliac spines in the position of the patient on the back);
– Kushelevsky-II test (pressure on the iliac wing in the position of the patient on his side);
– Kushelevsky-III test (in the position of the patient on the back, simultaneous pressure is applied to the inner surface of the knee joint bent at an angle of 90 ° and abducted and the upper anterior spine of the opposite wing of the ilium).
- Enthesopathies are manifested by pain in the area of attachment of fibrous structures to the bones, in particular, the iliac crests, large trochanters of the femur, spinous processes of the vertebrae, sternocostal joints, ischial tuberosities. With the development of bursitis, swelling appears.
- Eye damage in the form of anterior uveitis (iritis, iridocyclitis), usually bilateral, characterized by an acute onset, lasts 1-2 months, can take a protracted recurrent character; eye pathology is observed in 25-30% of patients.
Late stage symptoms
- Pain in various parts of the spine.
- Violation of posture, straightening of the physiological curves of the spine (“board-like back”) or “beggar’s posture”, pronounced kyphosis of the thoracic spine, tilting down and bending the legs at the knee joints, which compensates for the movement of the center of gravity forward.
- Atrophy of the rectus dorsi.
- A sharp decrease in chest excursions, in many patients breathing is carried out only due to the movements of the diaphragm.
- Limitation of mobility in the spine in 3-4 planes: sagittal (flexion, extension), frontal (tilts to the sides), vertical (rotation).
- Ankylosis of the sacroiliac and intervertebral joints.
- The defeat of the “root” (shoulder and hip) or peripheral joints. The hip joints are more commonly affected in patients whose onset is in childhood or adolescence. Peripheral joints are involved in 10-15% of patients, while predominantly large and medium joints of the lower extremities are affected by the type of mono- or oligoarthritis. Arthritis of the sternoclavicular (usually asymmetric), acromioclavicular, mandibular, and synchondrosis of the manubrium of the sternum may be observed. Peripheral arthritis can pass without a trace in 20-25% of patients.
- Damage to the cardiovascular system – aortitis, aortic valve insufficiency, pericarditis, myocarditis with various degrees of atrioventricular conduction disturbances, and the incidence of aortitis and atrioventricular conduction disturbances is much higher with a longer duration of the disease and the presence of peripheral arthritis.
- The defeat of the lungs in the form of slowly progressive fibrosis of the apical segments of the lungs.
- Kidney damage is rare, in 5% of cases in the form of amyloidosis or IgA nephropathy, and unlike idiopathic IgA nephritis, hematuria is rarely expressed.
- The central form – the defeat of only the joints of the spine and the sacroiliac joint.
- The rhizomelic form is a lesion of both the spine and the shoulder and hip joints.
- Peripheral form – in some cases, the disease of the joints of the extremities precedes the damage to the spine, in others – on the contrary, in the third – the joints and spine are simultaneously affected. The knee joints are most commonly affected.
- A variant similar to rheumatoid arthritis is damage to the joints of the hands and feet, morning stiffness. There are no clinical signs of spinal injury.
- The septic variant is characterized by an acute fever (up to 38-39 ° C) at the beginning of the disease, torrential sweat, arthralgia, myalgia, and weight loss.