Juvenile ankylosing spondylitis

Juvenile spondyloarthritis, or Bechterew's disease, is a group of clinically and pathogenetically similar rheumatic diseases of childhood, including juvenile ankylosing spondylitis, juvenile psoriatic arthritis, reactive (postenterocolitic and urogenic) arthritis associated with HLA-B27 antigen, Reiter's syndrome, enteropathic arthritis in inflammatory bowel diseases (regional enteritis, ulcerative colitis). In this group, undifferentiated spondyloarthritis is also distinguished (to designate those clinical situations when the patient has only individual manifestations characteristic of spondyloarthritis, and the entire symptom complex of a specific nosological form is absent, which, in fact, serves as a stage in the formation of the disease and, with natural evolution, usually leads to the development of juvenile ankylosing spondylitis or psoriatic arthritis).

The so-called seronegative arthro/enthesopathy syndrome (SEA syndrome), introduced into pediatric rheumatology practice in 1982 by Canadian scientists A. Rosenberg and R. Petty to differentiate it from juvenile rheumatoid arthritis, may be characteristic of the juvenile onset of undifferentiated spondyloarthritis. Acute anterior uveitis is also often considered as one of the variants of juvenile spondyloarthritis, provided that other causes of ophthalmologic pathology are excluded. The group of juvenile spondyloarthritis also includes rare syndromes associated with skin changes (pustulosis, acne) and osteitis (SAPHO syndrome, chronic recurrent multifocal osteomyelitis), which are more characteristic of children and adolescents than of adults.

General characteristics of juvenile spondyloarthritis:

• predominant incidence among males;
• features of the joint syndrome that differ from rheumatoid arthritis in clinical characteristics, localization and prognosis;
• absence of rheumatoid factor in the blood serum;
• frequent involvement of the spine in the pathological process;
• high frequency of carriage of the HLA-B27 antigen;
• tendency towards familial aggregation in HLA-B27-associated diseases.

Despite the pathogenetic justification for combining the listed diseases into a group of juvenile spondyloarthritis, the use of this term in everyday medical practice is associated with certain problems. Thus, the International Classification of Diseases, Tenth Revision (ICD-10) does not provide a separate category for the entire group of spondyloarthritis, therefore the use of the general term "juvenile spondyloarthritis" or the diagnosis "undifferentiated spondyloarthritis" coded in the category M46 in medical documents and statistical reporting forms distorts the data on the prevalence of rheumatic diseases in children. Juvenile ankylosing spondylitis according to ICD-10 is considered in the category M08 "Juvenile arthritis" and corresponds to item M08.1. Juvenile psoriatic arthritis and enteropathic arthritis are classified under the category M09, and reactive arthropathies - under the category M02. In practice, a significant number of children and adolescents suffering from spondyloarthritis are diagnosed with "juvenile chronic arthritis" (M08.3, M08.4) and even "juvenile rheumatoid arthritis" (M08.0), which is explained by the long period of non-specific clinical manifestations, the so-called prespondylic stage of the disease, which is typical for the juvenile onset of spondyloarthritis. Juvenile rheumatoid arthritis occupies a central place in the group of juvenile spondyloarthritis, being its prototype. This disease is usually considered as identical to ankylosing spondylitis) in adults, although significant features of the clinical picture of juvenile rheumatoid arthritis provide grounds for discussing its nosological isolation. The central position of AS/JAS in the group of spondyloarthritis is due to the fact that any of the diseases included in this group can not only have individual features of ankylosing spondylitis, but also ultimately lead to its development, which is practically indistinguishable from idiopathic ankylosing spondylitis.

Juvenile ankylosing spondylitis is a chronic inflammatory disease of the peripheral joints, tendon-ligament apparatus and spine, occurring before the age of 16, characterized by a predominant incidence in males, a tendency towards familial aggregation and an association with the HLA-B27 antigen.

A synonym for AS/JAS, which is gradually falling out of use in scientific literature, is the term “Bechterew’s disease”.

History of the study of juvenile spondyloarthritis

Ankylosing spondylitis is a disease known to mankind for many millennia. Archaeological excavations and studies of the bone remains of ancient people and animals have found reliable signs of this disease. The priority of the first scientific description of ankylosing spondylitis belongs to the Irish doctor Bernard O'Connor, who 300 years ago in 1691 and 1695, based on a human skeleton accidentally found in a cemetery, gave a detailed description of the morphological changes characteristic of ankylosing spondylitis.

Anatomical studies were long ahead of clinical studies of ankylosing spondylitis, and only in the 19th century did isolated clinical descriptions of the disease begin to appear in the literature. Even then, in the reports of Benjamin Travers, Lyons and Clutton, examples of the onset of ankylosing spondylitis in children and adolescents were given.

The article by V. M. Bekhterev "Stiffness of the spine with its curvature as a special form of the disease", published in 1892 in the journal "Doctor" laid the foundation for the allocation of ankylosing spondylitis as a separate nosological form and the introduction of the term "Bechterev's disease" into the everyday life of doctors. Sometimes in medical literature one can also encounter the term "Bechterev-Strumpell-Marie disease", which includes the names of two more scientists who stood at the origins of the study of ankylosing spondylitis. Thus, Strumpell in 1897 showed that the basis of the disease is a chronic inflammatory process in the spine and sacroiliac joints, and not in the "areas adjacent to the dura mater of the spinal cord", as V. M. Bekhterev believed. Marie in 1898 described the pisomyelic form of the disease, thereby combining the lesion of the axial skeleton and peripheral joints into a single process. The actual term "Ankylosing spondylitis", reflecting the morphological basis of the disease in its natural course, was proposed by Frenkel in 1904.

The publication in 1942 of the book by Scott SG "A monograph on adolescent spondylitis or ankylosing spondylitis" attracted the attention of doctors to the study of ankylosing spondylitis with juvenile onset. Until the mid-80s, this problem was covered in the literature only by isolated publications and only the last decade has been marked by a surge of interest in the issues of studying juvenile ankylosing spondylitis, which was reflected in the works of many foreign authors (Ansell B., Burgos-Vargas R., Bywatftrs E., Cassidy J., Harrier R., Jacobs B., Job-Deslandre C, Khan M., Petty R., Ramus-Remus C, Rosenberg A., Shaller J. and others). In our country, a significant contribution to the study of the problem of juvenile ankylosing spondylitis was made in the 80-90s by a series of publications by Professor A.A.

Epidemiology of juvenile spondyloarthritis

There are no exact data on the prevalence of juvenile spondyloarthritis; they are based mainly on mathematical calculations. If we take into account that among adults of the white race, manifest ankylosing spondylitis occurs with a frequency of 2:1000 and higher, and among all cases of ankylosing spondylitis, 15-30% are of juvenile onset, then the prevalence of juvenile spondylitis should be 0.03-0.06%. In clinical practice, juvenile spondyloarthritis is recognized much less often due to a significant delay in the development of the main pathognomonic manifestation of spondyloarthritis - spinal damage. The results of long-term follow-up observations in assessing nosological outcomes in adult patients show that juvenile spondyloarthritis accounts for up to 25-35% of all cases of juvenile arthritis. Foreign epidemiological studies, indicating that the disease of every 3-4th patient among patients with juvenile arthritis can be attributed to the group of juvenile spondyloarthritis, confirm these data. For example, according to the results of a large epidemiological study conducted in the USA, the incidence of juvenile spondyloarthritis (except for JPSA) is 1.44 per 100,000 population, while the incidence of juvenile arthritis in general is 4.08 per 100,000.

Like ankylosing spondylitis in adults, juvenile spondylitis and especially juvenile spondylitis are diseases with a pronounced gender determination. Boys get sick 6-11 times more often than girls, although most likely this ratio may actually be 5:1 or 3:1, since in females, both adults and children, ankylosing spondylitis often occurs submanifestly, and in pronounced clinical forms, rheumatoid arthritis is diagnosed more often than in men.

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Causes of Juvenile Spondyloarthritis

The etiology of juvenile spondyloarthritis is unknown, the cause of the development of this pathology is obviously polyetiological.

The current level of knowledge is limited by the understanding of predisposing factors and individual links in pathogenesis. The origin of this disease is determined by a combination of genetic predisposition and environmental factors. Among the latter, the most important role is played by infections, primarily some strains of Klebsiella, other enterobacteria, and their associations interacting with the antigenic structures of the macroorganism, for example, the HLA-B27 antigen. The high frequency of carriage of this antigen (70-90%) in patients with juvenile spondyloarthritis compared to 4-10% in the population confirms the role of HLA-B27 in the pathogenesis of the disease.

Causes and pathogenesis of juvenile ankylosing spondylitis

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Symptoms of Juvenile Spondyloarthritis

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.

Symptoms of Juvenile Ankylosing Spondylitis

Classification of juvenile spondylitis

Modern ideas about the relationship between diseases classified as spondyloarthritis can be reflected in the classification proposed in 1997 by Professor E.R. Agababova.

Classification of juvenile ankylosing spondylitis

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Diagnosis of juvenile spondyloarthritis

When diagnosing juvenile spondyloarthritis, one should be guided by existing classification and diagnostic criteria based on a combination of anamnestic data, clinical manifestations and the necessary minimum of additional studies:

• pelvic radiography;
• X-ray, MRI and CT of the spine and peripheral joints (if clinical data are available);
• slit lamp examination by an ophthalmologist to verify the presence and nature of uveitis;
• functional examination of the heart;
• immunogenetic analysis (HLA-B27 typing).

Diagnosis of juvenile ankylosing spondylitis

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Treatment of juvenile spondyloarthritis

Special emphasis in the treatment of juvenile spondyloarthritis should be placed on teaching the patient a rational regimen, developing the correct functional stereotype, a carefully developed set of therapeutic exercises (LFK) aimed at limiting static loads, maintaining correct posture, and maintaining sufficient range of motion in the joints and spine. It is important to orient the patient to perform daily physical exercises in order to prevent progressive kyphosis.

How is juvenile ankylosing spondylitis treated?

Prevention of juvenile spondyloarthritis

Primary prevention is not carried out, however, given the high risk of accumulation of related diseases in families, genetic counseling and HLA-B27 typing for unaffected siblings may be considered appropriate.