Regression of cervical disc herniation observed on magnetic resonance images.

STUDY DESIGN: A retrospective study of cervical disc herniation using results of repeated magnetic resonance imaging examinations.

OBJECTIVES: To clarify the cervical disc herniation morphological changes over time in order to establish a strategy for treatment.

SUMMARY OF BACKGROUND DATA: In the authors' previous magnetic resonance imaging follow-up study of patients with lumbar disc herniation, spontaneous regression was observed in the sequestration-type lesions, and it was found that the tendency toward regression differed based on the anatomic position of extruded disc material.

METHODS: Thirty-eight patients with cervical disc herniation who underwent repeated magnetic resonance imaging examinations were studied. The changes over time in herniated disc size were evaluated using this imaging technique. Evaluation showed the characteristics of those in whom spontaneous regression was found, such as extrusion pattern, and the clinical outcome was evaluated by symptoms.

RESULTS: In 15 patients (40%), the volume of herniated material was decreased. The interval from onset of symptoms to the initial examination was significantly shorter in the regression group than in the group that showed no change in disc herniation. By extrusion pattern, cervical disc herniation, which was divided into migration type on sagittal view and lateral type on axial view, most frequently exhibited spontaneous regression. All of the patients with radicular pain and upper limb amyotrophy were treated successfully with conservative therapy.

CONCLUSION: Although the possibility of the combination of hemorrhage and disc material could not be denied, active resorption of herniated material probably occurred during the acute phase. Extruded material exposed to the epidural space may be resorbed more quickly than that beneath the ligament. Vascular supply probably plays a role in the mechanism of resorption. The phase and position of extrusion were the significant factors affecting cervical disc herniation resorption. It was demonstrated that examination performed during the acute phase using magnetic resonance imaging is necessary for elucidation of the pathogenesis of cervical disc herniation, and that migrating, lateral-type herniations regress so frequently that conservative treatment should be chosen not only for patients with radicular pain, but also for those with upper limb amyotrophy.