Abstract
Aims: To investigate the prevalence and significance of a high-intensity zone in a group of patients asymptomatic for low back pain.
Methods: A prospective observational study of the prevalence of abnormal MR imaging in normal volunteers without a significant history of back pain. All volunteers underwent physical examination, psychometric testing, plain radiograph, magnetic resonance imaging, and dexa scanning. Films were blindly assessed for the prevalence of degenerative disc disease, osteoporosis, high intensity zone, disc prolapse and spinal stenosis.
Results: Following history, clinical examination and psychometric testing 13 of 63 (20%) patients were excluded from the study on the basis of previous back injury, leg pain or abnormal clinical findings. 50 volunteers were eligible for inclusion in the study. The presence of a high-intensity zone or annular disruption was determined by standardised criteria on T2-wieghted magnetic resonance images. The prevalence of a high-intensity zone in the patient population was 12 of 50 patients (24%). 32% of all disc prolapses were at the L4/5 level, 33% were at L5/S1 and 17% were at L3/4 the remainder were at various other levels.
Conclusions: The presence of a high-intensity zone does not reliably indicate the presence of symptomatic internal disc disruption. Magnetic resonance imaging is accurate in determining nuclear anatomy, however positive findings do not always correlate with history and clinical findings. The presence of abnormal imaging in asymptomatic patients reinforces the need for a detailed history and clinical examination in the evaluation of the lumbar spine.
The abstracts were prepared by Mr Ray Moran. Correspondence should be addressed to him at Irish Orthopaedic Associaton, Secretariat, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11.
