engleski

Usefulness of magnetic resonance imaging in early assesment of low back pain with possible inflammatory cause in children

Low back pain (LBP) is very common complaint in adults which often begins in childhood. Despite the increasing frequency, it is estimated only 24% of children with LBP visit a doctor. Nevertheless, those patients are very often seen in pediatric rheumatology outpatient clinic. Although most of the cases of LBP after exclusion of trauma are caused by benign musculoskeletal disease, a history of sacroiliac (SI) joint tenderness and/or inflammatory lumbosacral (LS) pain is one of the ILAR classification criteria for Entesitis related arthritis (ErA), a form of juvenile idiopathic arthritis (JIA) that includes most of the patients with juvenile spondyloarthritis (jSpA). Recognition of jSpA particularly early in the course of the disease represents a unique set of challenges and therefore all the patients with inflammatory back pain (IBP) and arthritis or enthesitis should be suspected for jSpA with possible involvement of sacroiliac and other vertebral joints. Since magnetic resonance imaging (MRI) is the preferred method of assessment both for axial inflammation and other possible musculoskeletal, infectious and malignant causes of LBP in children, it might be advisable to use it in assessment of LBP in children early after recognition of symptoms characteristic for inflammation. Objectives Were to evaluate the usefulness of early MRI in discovering inflammation of spinal joints and other possible causes of LBP in children not fulfilling ILAR classification criteria for ErA at the time of investigation. Thirty five children referred to our pediatric rheumatology outpatient clinic due to LBP lasting for more than three months, who fulfilled ASAS criteria for IBP and had sacroilic joint tenderness and positive FABRE test on examination, participated in the study. Their average age was 14.2 years (6-18 years) and 11 (31.4%) of them were boys. Five of study participants (14.3%) had arthritis and 19 (54.3%) had enthesitis confirmed by ultrasound, but none of them fulfilled ILAR criteria for ErA at the time of examination. Twelve (out of 15) had B27 antigen and 13 (37.1%) had a history of SpA related disease in a first degree relative. One of the patients had a diagnosis of ulcerative colitis, and one of psoriasis. All of the participants had normal CBC and CRP values with negative antinuclear antibodies and rheuma factor. None had neurological symptoms. MRI of sacroiliac joints with lumbal and thoracical regions of the spine was performed in one week period after initial exam on 1.5 T machine and interpreted by experienced musculoskeletal radiologist. Sacroiliac joints were examined using short-tau inversion-recovery (STIR) sequence in coronal and axial planes, T1 weighted images (WI) in coronal plane, fat-suppressed T1-WI in axial plane before and after contrast admission. STIR sequence in coronal and sagittal planes and T1- WI in sagittal plane were used in imaging of thoracolumbar spine. Nineteen (54, 3%) of patients had various pathological findings detected by the MRI. Four (11, 4%) had signs of inflammation with one even having an active sacroiliitis according to ASAS criteria. Schmorl nodes were discovered in six patients and three of them fulfilled criteria for Scheuermann disease, including one with the signs of inflammation. Two patients had stress reaction in lumbosacral region. Five patients had incipient degeneration of intervertebral discs. Three patients had disc protrusion without and one with radial nerve compression. After three months of follow up, 19 patients (54.3%) satisfied ILAR criteria for ErA, one for psoriatic arthrits and one, who also had an ulcerative colitis, satisfied criteria for undifferentiated arthritis. Differential diagnosis of LBP in children is very wide and it is difficult to distinguish inflammatory and other causes upon the first encounter with pediatric rheumatologist on the grounds of history and examination alone. In our study, all of the patients with LBP had some characteristics of IBP and ErA, but definite diagnosis of jSpA was subsequently established in sixty percent ͞only͟. Interestingly, almost twenty percent of them already had inflammatory changes of LS and SI joints discovered by MRI, while many others had signs of additional causes of LBP. Therefore, MRI performed early after referral to pediatric rheumatologist in all children with suspected IBP can be very useful in elucidating the cause of LBP and differentiation of those who need only symptomatic relief, orthopedic consultation or further follow up in pediatric rheumatology clinic. High cost of this approach can be justified with the benefit of early therapeutic intervention in those with established axial inflammation and the avoidance of unnecessary treatment in those with other causes.

MRI, low back pain, inflammatory disease

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