Annular tears and disk herniation: prevalence and contrast enhancement on MR images in the absence of low back pain or sciatica.

Purpose: To evaluate the prevalence and radiologic findings of annular tear (especially of contrast material enhancement), bulging disk, and disk herniation on T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images in people without low back pain (LBP) or sciatica.

Materials And Methods: Thirty-six volunteers without LBP and/or sciatica (18 with no symptoms in their lifetime and 18 who were pain free for at least 6 months) were examined with sagittal and axial T2-weighted fast spin-echo (SE) and sagittal gadolinium-enhanced T1-weighted fast SE imaging. The prevalence and MR findings of bulging disk, focal protrusion, extrusion, and nonenhancing or enhancing annular tears were assessed.

Results: The prevalence of bulging disk and focal disk protrusion was 81% (29 volunteers) and 33% (12 volunteers), respectively. There were no extrusions. Twenty-eight annular tears were found in 20 patients (56%); 27 tears (96%) also showed contrast enhancement.

Conclusion: Annular tears and focal disk protrusions on MR images, with or without contrast enhancement, are frequently found in an asymptomatic population. Extruded disk herniation, displacement of nerve root, and interruption of annuloligamentous complex are unusual findings in an asymptomatic population and can be more closely related to patients with LBP or sciatica.