Resorption of Massive Lumbar Disc Herniation
on MRI Treated with Epidural Steroid Injection:
A Retrospective Study of 28 Cases
Background: Although herniated disc fragments may resolve spontaneously, the optimal treatment option for massive lumbar disc herniation (LDH) has not been determined. Objective: To evaluate the extent of reduction in the size of massive LDH on magnetic resonance imaging (MRI) and the pain relief effect of transforaminal epidural steroid injection (TFESI) during the study period. Study Design: Retrospective evaluation. Setting: Hospital and ambulatory pain clinic, Korea. Methods: After Institutional Review Board approval, we conducted a retrospective review of 28 patients who underwent at least 2 MRIs during the period from January 2012 to December 2014. The size of the herniated mass was determined from the ratio of the anterior-posterior diameter of the spinal canal (C-value) to the maximum anterior-posterior diameter of the herniated disc (H-value) on axial MRI (C-H ratio). We also analyzed visual analogue scale (VAS) scores at baseline (T0), 2 weeks after the first and second TFESI (T1, T2), and at the second follow-up MRI (T3). Results: The mean C-value was 18.3 ± 2.9 mm. The mean H-value changed from 10.4 ± 1.9 mm to 4.5 ± 2.7 mm, and the mean C-H ratio changed from 58 ± 1.0% to 24 ± 1.4% (P < 0.001). Twenty-four of 28 patients demonstrated a reduction in the size of the herniation, and the mean reduction rate of the C-H ratio was 59%. In 4 patients, the LDH had not resolved on MRI, but the symptoms had diminished to such an extent that surgery was not required. The mean VAS score had significantly decreased at T1 and showed a continued decrease at the time of the last follow-up (P < 0.001). Limitations: This is a retrospective study and only offers data for patients who chose not to undergo surgery. In addition, the timing of repeat MRI was not standardized. Conclusion: The majority of cases of massive LDH demonstrated resolution at variable points between 3 and 21 months. TFESI could provide effective pain relief for patients with massive LDH in the interval without severe neurologic deterioration. IRB approval: Kangdong Sacred Heart Hospital: IRB Number # 14-1-10 Key words: Lumbar disc herniation, magnetic resonance imaging, migration, regression, resorption, sequestration, transforaminal epidural steroid injection