[Spontaneous regression of lumbar hernia of the nucleus pulposus. Follow-up study of 4 cases by repeated magnetic resonance imaging].

Introduction: As yet there have been no consistent magnetic resonance (MR) imaging studies on spontaneous regression of herniated lumbar nucleus pulposus (HNP). We present four patients in whom follow-up MRI images 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 made evolved favorably with conservative therapy.
Results: Follow-up MRI images revealed a remarkable regression of the HNP in the extrusion case and complete disappearance in the sequestration cases. In the extrusion case, follow-up MRI images showed rapid shrinkage of the portion extruded into the epidural space. In the sequestration cases, MR images with Gadolinium DTPA (enhanced MR images) showed that the enhanced lesion around the HNP had reduced its size as the HNP diminished. Final 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 images might have been due more to resorption than to dehydration.