Determinants of spontaneous resorption of intervertebral disc herniations

Abstract

Study design: A follow-up of disc herniation (herniated nucleus pulposus [HNP]) resorption on magnetic resonance imaging (MRI).

Objective: To assess the determinants of resorption of HNP.

Summary of background data: Neovascularization in the outermost areas of HNP, presenting as an enhancing rim in gadolinium diethylenetriamine pentaacetic acid MR images, is thought to be a major determinant of spontaneous resorption of HNP.

Methods: Patients with HNP-induced sciatica at baseline were rescanned at 2 months (N = 74) and after 12 months (N = 53). The volume of HNP (mm), thickness (mm) and extent (%) of enhancement, and the degree of HNP migration (Komori classification) were analyzed. Repeated measures analysis of covariance was used in statistical analysis.

Results: Significant resorption of HNP occurred from baseline to 2 months, although the resorption rate was more pronounced over the whole 1-year follow-up. Higher baseline scores of rim enhancement thickness, higher degree of HNP displacement in the Komori classification, and age category 41-50 years were associated with a higher resorption rate. Thickness of rim enhancement was a stronger determinant of spontaneous resorption than extent of rim enhancement. Clinical symptom alleviation occurs concordantly with a faster resorption rate.

Conclusions: MRI is a useful prognostic tool for identifying patients with HNP-induced sciatica with a benign natural course.