SPONTANEOUS REGRESSION OF HERNIATED LUMBA R NUCLEUS PULPOSUS FOLLOW-UP-STUDIES ON 4 CASES BY MAGNETIC-RESONANCE-IMAGING

Introduction As yet there have been no consistent magnetic resonance ( MR) imaging studies on spontaneous regression of herniated lumbar nucl eus pulposus (HNP). We present four patients in whom follow-up MRI ima ges demonstrated spontaneous regression or complete disappearance of a herniated lumbar nucleus pulposus. One patient presented with a large extruded type, and the rest had the sequestrated type. All patients m ade evolved favorably with conservative therapy. Results Follow-up MRI images revealed a remarkable regression of the HNP in the extrusion c ase and complete disappearance in the sequestration cases. In the extr usion case, follow-up MRI images showed rapid shrinkage of the portion extruded into the epidural space. In the sequestration cases, MR imag es with Gadolinium DTPA (enhanced MR images) showed that the enhanced lesion around the HNP had reduced its size as the HNP diminished. Fina l MR images could not detect the HNP in any view of the spinal canal. Conclusion We therefore concluded that the regression of HNP in MR ima ges might have been due more to resorption than to dehydration.