Spontaneous regression of lumbar disc herniation: four cases report and review of the literature.

Spontaneous regression of lumbar disc herniation refers to shrinkage or disappearance of herniated nucleus pulposus without invasive surgical treatments. This phenomenon has been reported and is supported by improved clinical symptoms and radiographic after conservative treatment, but the underlying mechanism remains unclear. This article reports 4 cases of disc reabsorption and reviews the distribution of several clinical and radiographic factors of disc herniation reabsorption of total 46 patients, including the four from our study, gathered from 28 recent publications. Some of these factors are present with anomalous distributions. But some factors have similar deviations in patients with lumbar disc herniation. Therefore, more research is needed to explore the correlation between those factors and disc reabsorption.