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Diagnosis of juvenile ankylosing spondylitis

 
, medical expert
Last reviewed: 04.07.2025
 
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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).

The most acceptable, generally accepted classification criteria for the entire group of juvenile spondyloarthritis are the criteria proposed by the European Spondyloarthropathies Study Group (ESSG), which have received high marks for their sensitivity and specificity in international multicenter studies.

Classification criteria of the European Spondyloarthropathies Study Group

  • Spinal pain and/or arthritis (asymmetrical; predominantly lower extremities).
  • One or more of the following criteria (current or history):
    • the presence of ankylosing spondylitis, psoriasis, reactive arthritis, Crohn's disease or ulcerative colitis in first- or second-degree relatives;
    • psoriasis;
    • inflammatory bowel disease (Crohn's disease or ulcerative colitis, confirmed by radiography or endoscopic examination);
    • urethritis, cervicitis or acute diarrhea that occurred 1 month before the onset of arthritis;
    • intermittent pain in the buttocks;
    • heel pain;
    • sacroiliitis confirmed by radiography (bilateral stages II-IV or unilateral stages III-IV).

Classification criteria of spondyloarthritis are optimal for distinguishing this group of diseases from juvenile rheumatoid arthritis, however, the inclusion of this group term in the diagnosis formulation is inappropriate, since this means the concept of "undifferentiated spondyloarthritis" and the diagnosis in accordance with ICD-10, the diagnosis is coded as M46, i.e. outside the rubric of juvenile arthritis (M08). The diagnosis of juvenile chronic arthritis (JCA) is the most acceptable for designating prespondylic stages of juvenile ankylosing spondylitis, when the disease cannot yet meet the generally recognized criteria of AS. It is this diagnosis that makes it possible not to make an obviously incorrect diagnosis of juvenile rheumatoid arthritis in those situations when there is a high probability of further development of spondyloarthritis. In order to focus attention on the predicted outcome, it is justified to include the clarification “HLA-B27-associated” in the formulation of the diagnosis of JHA in those patients who underwent immunogenetic testing and the HLA-B27 antigen was detected.

Verification of the diagnosis of juvenile ankylosing spondylitis is only valid if the internationally recognized criteria for ankylosing spondylitis are met, the most common of which are currently the modified New York criteria. It should be taken into account that these criteria are focused mainly on manifest spinal lesions and radiographic confirmation of sacroiliitis. This circumstance makes it problematic to use these criteria for diagnosing early stages of the disease, especially in childhood, given the delayed involvement of the axial skeleton in the process, which is typical for juvenile onset, and the difficulties in radiographic verification of sacroiliitis in children and adolescents due to the incompleteness of skeletal ossification processes.

Modified New York criteria for ankylosing spondylitis

Criteria

Symptoms

X-ray

Sacroiliitis: bilateral stage II or unilateral stage III-IV

Clinical criteria

Pain and stiffness in the lower back that lasts at least 3 months, is relieved by exercise, and is not relieved by rest

Limitation of mobility of the lumbar spine in the sagittal and frontal planes

Decreased chest excursion in relation to the age norm

Criteria for the diagnosis of ankylosing spondylitis

The diagnosis of definite ankylosing spondylitis is established in the presence of radiographic and at least one clinical criterion

Probable ankylosing spondylitis may be suspected based on clinical criteria alone or radiographic findings alone.

There are also international diagnostic criteria (developed specifically for the diagnosis of juvenile ankylosing spondylitis by a group of German rheumatologists), known in the literature as the Garmisch-Partenkirchten criteria, which, despite their high sensitivity and specificity, are not generally recognized today and do not allow for the verification of the diagnosis of juvenile ankylosing spondylitis.

Criteria for juvenile ankylosing spondylitis (Garmisch-Partenkirchen, 1987)

Main criteria

Additional criteria

Asymmetrical pauciarthritis (less than five joints), predominantly of the lower extremities at the onset of the disease (in the first 3 months)

Polyarthritis (more than four joints) at the onset of the disease

Enthesopathy

Male gender

Pain in the lumbosacral region

Age of onset of the disease is more than 6 years

Acute iridocyclitis

Presence of HLA-B27 antigen

Familial aggregation of diseases from the group of seronegative spondyloarthritis

Two main criteria or one or two main and two additional - probable juvenile ankylosing spondylitis; the same criteria and radiologically reliable sacroiliitis (bilateral stage II or unilateral, at least stage III) - definite juvenile ankylosing spondylitis.

Vancouver diagnostic criteria for juvenile psoriatic arthritis

Definite juvenile psoriatic arthritis: arthritis and typical psoriatic rash, or arthritis and three of the following ("minor") criteria:

  • changes in nails (thimble symptom, onycholysis);
  • psoriasis in first or second degree relatives;
  • psoriasis-like rash;
  • dactylitis.

Probable juvenile psoriatic arthritis: arthritis and two of the four minor criteria.

The main diagnostic criteria for Reiter's disease in children (triad of changes):

  • arthritis;
  • conjunctivitis;
  • urethritis.

The diagnosis of enteropathic arthritis (against the background of chronic inflammatory bowel diseases) is made in the presence of:

  • arthritis;
  • chronic bowel disease (Crohn's disease, ulcerative colitis), verified by endoscopic and histological examination.

An important aspect of juvenile ankylosing spondylitis diagnostics is a physical examination with assessment of the functional state of the spine. The ASAS Working Group (an international expert group that collects clinical and scientific data using expert opinions and statistical approaches to better assess and understand the evolution of AS) recommends using easily performed assessment methods for assessing spinal mobility that objectively reflect changes in all parts of the spine.

To identify movement limitations in the sagittal plane, the Thomayer symptom is used - determining the distance from the fingertips to the floor with maximum forward bending, without bending the knees. Normally, it should not exceed 5 cm. It should be taken into account that a patient with limited spinal mobility, but with good mobility in the hip joints, can reach the floor, the lumbar spine will remain straight, without the upward convex arc that is typical for a healthy person. This test, when applied to the pediatric population, does not have the necessary specificity, since it is often determined in children and adolescents with non-inflammatory orthopedic pathology and with a banal violation of posture and physical detraining of the child.

To assess the mobility of the lumbar spine, the Schober test is used: with the patient standing, a point is marked on the imaginary line connecting the posterior superior iliac spines along the midline of the back. Then a second point is marked, 10 cm above the first. After that, the patient is asked to bend forward as much as possible without bending the knees, and in this position, the distance between the two points is measured. Normally, it should increase to 15 cm or more. It should be taken into account that this test evaluates the functional state of the lumbar spine itself, which is affected later than the lower thoracic spine in juvenile ankylosing spondylitis. The modified Schober test is more informative; it differs from the previous one in that two points are marked 5 and 15 cm above the line connecting the posterior superior iliac spines. Based on population studies of children and adolescents of different sexes and ages, foreign scientists have established and summarized in appropriate tables the normal values for the modified Schober test.

The diagnostic criteria take into account the limitations of the lumbar spine mobility in two planes, so it is necessary to evaluate the movements of the lumbar spine in the frontal plane as well. To do this, measure the lateral flexion in this section. First, determine the distance between the tip of the middle finger and the floor, then ask the patient to bend to the side (without bending the body forward or bending the knees), and measure this distance again using a vertical ruler on the floor. In this case, evaluate the difference between the initial distance and the distance after bending. Normally, this difference should be at least 10 cm.

To assess the function of the thoracic spine, the Ott test is performed, determining the distance between two points: at the level of the 7th cervical vertebra and 30 cm below. Normally, when tilted, it increases by 5-7 cm. It should be emphasized that this test must be performed correctly, requiring maximum straightening of the back before measurements. It has low specificity, since in patients with juvenile kyphosis (Scheuermann-Mau disease) it often shows lower values compared to patients with juvenile ankylosing spondylitis.

Limitation of chest excursion is an important test included in the criteria for the diagnosis of ankylosing spondylitis, which may indicate the involvement of the costovertebral and costosternal joints in the pathological process. Chest excursion is the difference between its circumference during inhalation and exhalation at the level of the 4th rib. Normally (depending on gender and age), it should be at least 5 cm.

When the cervical spine is involved, it is necessary to evaluate mobility in all directions, since in juvenile ankylosing spondylitis, unlike osteochondrosis, all types of movement are impaired. Flexion in the cervical spine is assessed by measuring the chin-sternum distance, which should normally be 0 cm. To determine the severity of cervical kyphosis, the Forestier symptom is used, measuring the distance from the back of the head to the wall when the patient is placed with his back to the wall with the shoulder blades, buttocks and heels pressed against it. The inability to reach the wall with the back of the head indicates damage to the cervical spine, and the distance measured in centimeters can serve as a dynamic indicator of its severity.

Rotations and tilts in the cervical spine are measured using a goniometer, and normally the rotation angle should be at least 70°, and the lateral tilt angle should be at least 45°.

Instrumental studies help in identifying inflammatory and structural changes in the musculoskeletal system.

Radiological assessment of axial skeletal lesions in children and adolescents presents significant difficulties due to the incompleteness of skeletal ossification processes. It is known that on pelvic radiographs in childhood, the articular surfaces of intact sacroiliac joints may not look smooth and clear enough, and their gaps often have an uneven width, which can be mistakenly interpreted as manifestations of sacroiliitis. At the same time, even with significant expression of growth zones, it is possible to identify indisputable radiological changes in the sacroiliac joints, for example, osteosclerosis with the so-called phenomenon of pseudo-expansion of the joint space or pronounced erosions with isolated bone "bridges" corresponding to stage III and even complete ankylosis.

There are several gradations of radiological assessment of sacroiliitis. The most common and widely known is the division into four stages according to Kellgren (included in the diagnostic criteria).

Radiographic stages of sacroiliitis according to Kellgren (New York criteria)

Stage

Changes

Peculiarities

0

Norm

No changes

1

Suspected sacroiliitis

Suspected changes (blurred joint edges)

II

Minimum

Small localized areas of erosion or sclerosis without changes in the width of the joint space

III

Moderate

Moderate or severe signs of sacroiliitis: erosions, sclerosis, widening, narrowing or partial ankylosis of the joint

IV

Significant

Significant changes with complete ankylosis of the joint

These criteria are similar to the five stages of sacroiliitis proposed by K. Dale. Common features for both gradations:

  • Stage I includes changes suspicious of sacroiliitis, i.e. subchondral osteosclerosis, some unevenness and blurring of the articular surfaces, which does not exclude the possibility of a normal age-related radiographic picture;
  • Stage II includes obvious pathological changes (pronounced osteosclerosis not only on the iliac but also on the sacral sides of the joint space, pseudo-widening of the joint space and/or limited areas with erosions).

According to the Dale classification, psoriatic arthritis is divided into stages (unilateral changes) and lib (bilateral changes); stage III reflects in more detail the possibility of regression of subchondral sclerosis and the presence of erosions; stage IV - partial ankylosis (formally corresponds to stage III according to Kellgren); stage V - complete ankylosis. For quantitative accounting of damage to the overlying parts of the spine, the ASAS expert group proposed the BASRI radiographic progression index, assessed in points according to the following positions.

  • Radiological stage of sacroiliitis (0-4 points).
  • X-ray changes in the spine (direct and lateral projections of the lumbar and lateral projections of the cervical spine) with a scoring assessment of the severity of changes in each segment according to the following gradations:
    • 0 - normal (no changes)
    • I - suspicion (no obvious changes);
    • II - minimal changes (erosion, squaring, sclerosis ± syndesmophytes on two or more vertebrae);
    • III - moderate changes (syndesmophytes of more than three vertebrae ± fusion of two vertebrae);
    • IV - significant changes (fusion involving more than three vertebrae).

The use of CT in diagnostics of axial skeletal lesions, especially sacroiliac joint lesions, is invaluable in identifying changes when radiography is insufficiently informative. The ability to obtain cross-sectional images of the sacroiliac joints allows for visualization of structural changes in all areas of the joint spaces and a much more accurate picture of the first bone changes (disappearance of continuity of the endplate, local erosions, subchondral osteosclerosis, pseudo-widening of the space). MRI helps to identify early inflammatory changes in the sacroiliac joints and overlying structures of the spine, however, the methodology for using this method in diagnosing JAS still needs to be studied and refined.

Ultrasound imaging can confirm synovitis in peripheral joints, which is important for assessing activity and treatment tactics.

Changes in laboratory parameters in juvenile ankylosing spondylitis are nonspecific and cannot be of significant use either in diagnostics or in developing treatment tactics. According to data from various authors and our observations in 1/4 of patients with juvenile ankylosing spondylitis, as well as in ankylosing spondylitis in adults, the ESR value and other acute inflammatory indices never exceed normal values. At the same time, another 1/4 of patients are characterized by high humoral activity, often tending to persist and correlating, as a rule, with the severity of peripheral arthritis.

HLA testing has a certain clinical significance, in particular the detection of B27 and antigens included in the B7-CREG-rpynny ("cross reactive group"). It is important to note that immunogenetic testing plays a prognostic rather than a diagnostic role, since the B27 antigen is present in the genotype of far from all patients with juvenile ankylosing spondylitis (75-90%), but its presence determines some features of the course of the disease. Carrying the HLA-B27 antigen is associated with a higher frequency of polyarthritis, tarsitis, involvement of small joints of the hands and feet, dactylitis, uveitis, persistence of high laboratory activity, as well as higher absolute activity indicators, especially ESR, C-reactive protein and IgA.

Differential diagnostics

At those stages when the clinical picture of the disease is represented by an isolated joint syndrome, important differential diagnostic significance is attached to the qualitative characteristics of arthritis, which primarily allows us to distinguish between juvenile ankylosing spondylitis and diseases of the spondyloarthritides circle.

The distinction between juvenile ankylosing spondylitis and other juvenile spondyloarthropathies is based mainly on anamnestic data on the chronological connection of the disease with an acute episode of intestinal or urogenital infection, as well as the presence of skin psoriasis, Crohn's disease or nonspecific ulcerative colitis in the patient or his immediate relatives. It should be emphasized once again that a clear distinction between juvenile ankylosing spondylitis and other spondyloarthropathies is not always possible due to the commonality of the main clinical signs, the tendency to form cross syndromes between diseases of this group and the possibility of forming a clinical picture of juvenile ankylosing spondylitis in the outcome of any spondyloarthritis.

A necessary condition for differential diagnostics of juvenile ankylosing spondylitis is the exclusion of all non-rheumatic diseases capable of causing clinical symptoms similar to those of juvenile ankylosing spondylitis: septic and infectious (tuberculosis, brucellosis, etc.) arthritis or sacroiliitis, various pathologies of the musculoskeletal system of non-inflammatory genesis (dysplasia, osteochondropathy, etc.). In rare cases, it may be necessary to differentiate from hematological diseases or neoplasms. Among malignant neoplasms, "rheumatic masks", especially articular syndrome, ossalgia and back pain, most often occur with systemic blood diseases, neuroblastoma and a group of primitive neuroectodermal tumors (Ewing's sarcoma, etc.).

In case of acute local symptoms of damage to the axial skeleton with significant pain syndrome and the absence of peripheral arthritis in a child, it is first necessary to exclude diseases of the non-rheumatic circle.

Acute manifestations of arthritis in a limited number of joints, especially combined with signs of periarticular damage, require the exclusion of osteomyelitis, both acute, subacute, and chronic multifocal. The latter is also characterized by symptoms of damage to the axial skeleton, sometimes with a significant pain component, and with a long course - the development of destruction of not only peripheral joints, but also vertebral bodies.

Indications for consultations with other specialists

  • Ophthalmologist. All patients with juvenile arthritis are examined with a slit lamp every 3-6 months to exclude subclinical development of uveitis and complications of drug treatment; in the oligoarticular variant of juvenile arthritis, to exclude subclinical development of uveitis and complications of drug treatment with an early age of onset and the presence of ANF.
  • Endocrinologist. It is necessary to monitor patients with juvenile arthritis to exclude subclinical development of uveitis and drug complications with pronounced signs of exogenous hypercorticism, growth disorders, and impaired glucose tolerance.
  • Otolaryngologist. Examination is necessary to find and treat foci of chronic infection in the nasopharynx.
  • Dentist. They detect caries, growth disorders of the jaws, teeth and bite. They examine patients with suspected "dry syndrome" (Sjogren's syndrome).
  • Phthisiatrician. Consultation is necessary in case of a positive Mantoux test, lymphadenopathy, to decide on the possibility of using anti-cytokine treatment with TNF-a blockers.
  • Orthopedist. Patients are examined for functional insufficiency of joints, impaired bone growth in length, subluxations, to develop rehabilitation measures, and determine indications for surgical treatment.
  • Geneticist. Consultation is necessary in case of multiple minor developmental anomalies, connective tissue dysplasia syndrome.

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