Symptoms of juvenile ankylosing spondylitis

Since juvenile ankylosing spondylitis serves as a prototype for the entire group of juvenile spondyloarthroses, its characteristic clinical manifestations occur in all diseases of this group in the form of individual symptoms or their combinations.

60-70% of children develop juvenile spondylitis at the age of over 10 years, however, in rare cases there is an early onset (before 7 years), the debut of juvenile ankylosing spondylitis at the age of 2-3 years has been described. The age of onset of the disease determines the spectrum of clinical manifestations at the debut of juvenile ankylosing spondylitis and the patterns of its further course.

The clinical symptom complex of juvenile ankylosing spondylitis consists of four main syndromes:

• peripheral arthritis (usually oligoarthritis with predominant damage to the lower extremities, usually asymmetrical);
• enthesopathies - inflammatory changes at the sites of attachment of tendons and ligaments to bones;
• extra-articular manifestations with typical damage to the eyes, heart, mucous membranes, skin, and possible involvement of internal organs in the process (for example, IgA-associated nephropathy);
• damage to the axial skeleton - joints, ligaments and other anatomical structures of the spine and adjacent joints (sacroiliac, pubic, sternoclavicular, clavicular-acromial, sternocostal, costovertebral, manubrio-osternal).

Variants of the debut of juvenile ankylosing spondylitis Depending on the primary localization of the pathological process, several variants of the debut are conventionally distinguished:

• isolated peripheral arthritis;
• combination of arthritis and enthesitis (SEA syndrome);
• simultaneous damage to peripheral joints and axial skeleton (in 1/4 of patients);
• isolated enthesitis;
• isolated lesion of the axial skeleton;
• isolated eye lesion.

The first three types of onset occur in 90% of patients, while the last three occur in rare observations and only in children over 10 years of age.

Within the limits of childhood and adolescence, the course of juvenile ankylosing spondylitis is generally relatively benign, mostly recurrent. Long remissions are typical, the duration of which sometimes reaches 8-12 years. However, as the child grows older, the disease acquires a chronic, progressive course, especially due to the increase in symptoms of damage to the axial skeleton and coxitis; in the long-term aspect, juvenile ankylosing spondylitis is characterized by a more severe prognosis in comparison with ankylosing arthritis in adults.

Peripheral arthritis

The main clinical features of peripheral arthritis in juvenile spondyloarthritis:

• oligoarticular or limited polyarticular lesion,
• asymmetry;
• predominant damage to the joints of the lower extremities;
• combination with enthesitis and other tendon-ligament symptoms;
• non-destructive nature (except for tarsitis and coxitis);
• relatively benign course with the possibility of complete regression and a tendency to develop long-term, including multi-year, remissions.

The most common localization of peripheral arthritis is the knee and ankle joints. If the asymmetrical nature of the joint syndrome is clearly expressed, or arthritis is most persistent in only one joint and to a much lesser extent in others, irritation of the epiphyseal growth zones (most often in the knee joint) often leads to lengthening of the affected limb. This mechanism of formation of the difference in length should be distinguished from the relative shortening of the leg in arthritis of the hip joint, which can occur due to several reasons: flexion-adduction contracture, subluxation or destruction of the femoral head. Coxitis is the most prognostically serious manifestation of peripheral arthritis, which can lead to disability of patients and cause the need for endoprosthetics in a fairly short time.

The defeat of the joints of the tarsus with the formation of the so-called ankylosing tarsitis is a typical clinical symptom of diseases of the circle of juvenile spondylitis in children, especially juvenile ankylosing spondylitis. This peculiar defeat of the articular and tendon-ligament apparatus of the foot is clinically manifested by a pronounced defiguration of the tarsus area, as a rule, with a significant pain component, a change in the color of the skin due to inflammatory changes, usually combined with defeat of the periarticular soft tissues (Achillobursitis, plantar fasciitis, tenosynovitis in the area of the outer and inner malleolus), accompanied by gait disturbance, sometimes up to the loss of the ability to support the limb. Radiographically, tarsitis is manifested by osteopenia, often pronounced, erosion of the articular surfaces of the tarsal bones, sometimes in combination with bone growths and periosteal layers, and with a long course - the development of ankylosis in the joints of the tarsus. The presence of such joint damage allows almost completely to exclude the diagnosis of juvenile rheumatoid arthritis and to predict the development of spondyloarthritis in the patient.

At one stage or another of the disease development, any joints may be involved in the pathological process, although there remains a tendency for arthritis of the lower extremities to predominate and for the joints of the "cartilaginous" type to be affected, which belong to the structures of the axial skeleton: sternoclavicular, clavicular-acromial, costosternal, manubriosternal, pubic articulations, etc. Some patients may have isolated lesions of the joints of the first finger of the hand, which usually does not bother the child much, but this is revealed during a clinical examination.

Formally, peripheral arthritis is rarely limited to the boundaries of a truly oligoarticular lesion and often affects more than five joints, however, persistence of arthritis occurs only in a certain number of joints. In most patients, the joint syndrome is unstable and subsequently undergoes complete reverse development, often without any residual changes. Torpid course of arthritis is typical for the hip, ankle and tarsal joints, to a lesser extent - the knee and first toes, and usually in those joints with the lesion of which the disease debuted.

Peripheral arthritis in other joints is predominantly non-erosive, however, destructive coxitis may develop in 10% of patients, the nature of which is fundamentally different from destructive coxitis in "classical" juvenile rheumatoid arthritis. Unlike aseptic necrosis of the femoral heads, characteristic of juvenile rheumatoid arthritis, especially its systemic variant, osteolysis and fragmentation of the head almost never develop in juvenile ankylosing spondylitis. Characteristic signs of destructive coxitis in juvenile ankylosing spondylitis are a tendency to gradual narrowing of the hip joint space with the development of ankylosis and bone proliferation. In some patients with juvenile spondyloarthritis, single erosions may appear in the distal parts of the feet, usually localized at the sites of attachment of the joint capsule, which essentially represents a variant of enthesopathies.

Peripheral arthritis in juvenile spondyloarthritis is often associated with damage to periarticular tissues in the form of tenosynovitis, tendinitis, as well as various localizations of enthesopathies, which serve as a fairly specific manifestation of juvenile spondyloarthritis.

Enthesopathies (extra-articular musculoskeletal symptoms)

Most authors note that this symptom is detected in children much more often than in ankylosing spondylitis in adults, and the prevalence of enthesopathies is 30-90%, with about 1/4 of patients having these symptoms already at the onset. The addition of this symptom is possible at almost any stage of the disease, but it is extremely rarely detected in patients under 10 years of age.

The favorite localization of enthesopathies is the area of the calcaneal bones. The clinical manifestations of Achilles bursitis and calcaneal bursitis facilitate their detection, while a thorough physical examination is necessary to detect enthesopathies of other localizations. Palpation pain in the places of attachment of ligaments and tendons of muscles to bones, as well as signs of tendinitis are most often detected in the area of the tuberosities of the tibia, patella, external and internal malleoli, heads of metatarsal bones, greater and lesser trochanters, iliac crests, ischial tuberosities, scapular spines, and olecranon processes. In practice, one can also observe tendon-ligament symptoms of an unusual nature, in particular with localization in the area of the inguinal ligaments, which can be accompanied by intense pain and local muscle tension in the groin area, simulating acute surgical pathology. In rare situations, ossifying tendinitis may occur in the occipital protuberance area.

Radiological signs of enthesopathies are most often osteophytes along the lower edge of the calcaneal tuberosity, or bone erosion in the places of tendon fixation, the initial signs of which can be detected by computer and MRI. In isolated cases, erosions and periostitis are possible in the area of the iliac crests, ischial bones, trochanters and other places of enthesitis.

Dactylitis, expressed in "sausage-shaped" defiguration of the fingers due to simultaneous inflammatory damage to the articular and tendon-ligament apparatus, which occurs both on the upper and lower extremities, is a peculiar manifestation of enthesitis. Dactylitis is a typical symptom of juvenile psoriatic arthritis, but it can also be detected in other juvenile spondyloarthritides. With persistent dactylitis, periosteal reaction may develop, requiring differential diagnosis with non-rheumatic conditions. Pain in the buttocks, characteristic of juvenile spondyloarthritis, is usually associated with inflammation in the sacroiliac joints, however, there is evidence explaining this symptom by the involvement of periarticular soft tissues and polyenthesitis in the pathological process.

Extra-articular manifestations

Eye damage is one of the most significant extra-articular symptoms of juvenile ankylosing spondylitis, most often represented by acute anterior uveitis (iridocyclitis), occurring in 7-10% of patients in childhood and in 20-30% in adolescence and adulthood. Bright clinical symptoms with sudden redness of the eyeball, pain and photophobia are typical, but some patients may have a low-symptom course of uveitis. In isolated cases, the pathological process affects all parts of the choroid (panuveitis), not limited to the anterior segment of the uveal tract. With rare exceptions, uveitis occurs in carriers of the HLA-B27 antigen. Some patients may have episcleritis in the form of short-term and benign episodes.

Heart involvement is a rare manifestation of juvenile ankylosing spondylitis, occurring in less than 3-5% of patients with juvenile ankylosing spondylitis. It occurs in isolation or as a combination of the following symptoms:

• lesion of the proximal aorta, diagnosed only by echocardiography;
• aortic insufficiency;
• atrioventricular block I-II degree.

Pericarditis occurs extremely rarely.

Kidney damage in patients with juvenile ankylosing spondylitis may be the result of several causes:

• secondary amyloidosis, a rare complication of uncontrolled progression of the process in patients with persistent high disease activity;
• IgA-associated nephropathy, observed in 5-12% of patients:
  • manifests itself as isolated hematuria or in combination with slight proteinuria;
  • develops against the background of high disease activity;
  • characterized by high levels of serum IgA;
• side effects of drugs (LS) - NSAIDs or sulfasalazine;
• ascending infection in urogenital reactive arthritis.

Axial skeletal disorder

Axial skeletal involvement is a pathognomonic manifestation of juvenile ankylosing spondylitis, the main feature of which, unlike ankylosing spondylitis in adults, is the delayed development of axial symptoms. Juvenile ankylosing spondylitis is characterized by the so-called prespondylolisthesis stage, the duration of which before the first symptoms of spinal involvement can be several (sometimes more than 10-15) years. A short prespondylolisthesis stage is possible, and the clinical picture of spondylitis occurs simultaneously with other manifestations if the child became ill at the age of 12-16. In young children (up to 5-6 years old), the delay between the first symptoms of the disease and the development of the typical clinical picture of juvenile ankylosing spondylitis can be 15 years or more. This identified pattern suggests that the key pathogenetic mechanisms of ankylosing spondylitis development are in close interaction with the physiological processes of maturation, primarily neuroendocrine or genetic factors that determine them.

The first clinical sign of axial involvement is usually pain in the projection of the sacroiliac joints and the buttocks, manifested both by active complaints and during physical examination. Sometimes the symptoms of sacroiliitis are combined with damage to the lumbar and lower thoracic or cervical spine. Intense, mainly nocturnal, back pain typical of adults is not typical in childhood. Most often, children have intermittent complaints of fatigue and tension in the back muscles with an inflammatory rhythm, i.e. occurring in the early morning hours and decreasing after physical exercise. Sometimes local soreness, limited range of motion, smoothing of the physiological curves of the spine, especially lumbar lordosis, and regional muscle hypotrophy are detected. In some patients, these symptoms are significantly reduced or completely disappear after adequate treatment, and repeated relapses may occur only after several years.

Clinical symptoms of axial skeletal damage are confirmed by radiographic signs of sacroiliitis and the overlying parts of the spine. In juvenile ankylosing spondylitis, in contrast to ankylosing spondylitis in adults, syndesmophytes occur much less frequently and at a much later stage, but it is possible to detect compaction of the anterior longitudinal ligament (especially its lateral parts at the level of the lower thoracic segments of the spine), which becomes increasingly manifest as the skeleton grows and develops, as well as the progression of spondylitis. Intervertebral joints are affected with the same frequency, both in juvenile ankylosing spondylitis and in ankylosing spondylitis in adults, but, as a rule, at later stages of the disease. Sometimes the radiographic manifestation of arthritis of the intervertebral joints, for example, in ankylosis of the facet joints in the cervical spine, exceeds the clinical manifestations. Spondylodiscitis can also act as one of the clinical and radiographic signs of spinal damage, characteristic of juvenile ankylosing spondylitis.

The dynamics of the disease development in juvenile ankylosing spondylitis is characterized by a clear dependence on age of the spectrum of clinical manifestations with gradual partial regression of some symptoms and manifestation of others. As the child grows and matures, there is a tendency for a gradual decrease in the frequency and severity of relapses of peripheral arthritis and enthesitis and, conversely, a greater manifestation of damage to the eyes and axial skeleton. Age-related evolution of clinical symptoms of the disease leads to a typical clinical picture of ankylosing spondylitis over the age of 20.

Juvenile psoriatic arthritis occupies a special place among juvenile ankylosing spondylitis. Skin psoriasis is not always a mandatory criterion for the diagnosis of juvenile psoriatic arthritis if the patient has specific joint manifestations and there is accurate information about the presence of psoriasis in first-degree relatives. The appearance of skin changes and/or mucous membrane lesions typical of psoriasis can occur both simultaneously with the joint syndrome and several years (up to 10-15) after the onset of arthritis. As a rule, parallelism in the timing and severity of peripheral arthritis and skin psoriasis in juvenile psoriatic arthritis is not observed.

Juvenile psoriatic arthritis can occur at any age, which, as a rule, determines the characteristics of the clinical manifestations of the disease.

• Children under 7 years of age often develop oligoarthritis (possibly affecting both the lower and upper extremities) in combination with dactylitis.
• In children over 7 years of age, with a general predominance of oligoarticular variants of joint syndrome, polyarthritis often occurs, up to destructive mutilating arthritis.
• The spondyloarthritic variant, which is relatively rare for children, develops almost exclusively in adolescents and is characterized by the same clinical features as the entire group of juvenile spondyloarthritides.
• A rare and most severe mutilating variant of juvenile psoriatic arthritis occurs mainly with early (up to 5 years) onset of the disease, developing multidirectional subluxations, dislocations, multiple deformations and contractures, especially in the distal parts of the extremities. Characteristic joint manifestations of juvenile psoriatic arthritis:
  • arthritis of the distal interphalangeal joint;
  • axial lesion of three joints on one finger;
  • dactylitis;
  • periostitis;
  • intra-articular osteolysis of the "pensik-in-cup" type ("pencil in a cup");
  • acral osteolysis;
  • mutilating arthritis.

Extra-articular manifestations of juvenile psoriatic arthritis do not differ from those of other spondyloarthritides.

The clinical features of joint damage in enteropathic arthritis (associated with Crohn's disease, nonspecific ulcerative colitis) are identical to juvenile spondylitis and do not differ in any specificity.

In terms of peripheral arthritis, there is a certain similarity with juvenile spondylitis in two rare pathological conditions associated with skin manifestations and osteitis - chronic recurrent multifocal osteomyelitis and SAPHO syndrome (abbreviation for "S" - synovitis, "A" - aspe con- globata, round deep acne, "P" - pustulosis, "H" - hyperostosis, "O" - osteitis). A distinctive feature of this pathology is multiple bone lesions in extra-articular locations, especially the clavicles, pelvic bones, vertebral bodies, etc. In this case, osteomyelitis is aseptic in nature, in any case, attempts to isolate the pathogenic agent from the lesion are usually unsuccessful.

[ 1 ], [ 2 ]