Inhibition of epidural fibrosis after microendoscopic discectomy with topical application of mitomycin C: a randomized, controlled, double-blind trial

Abstract

Object The authors conducted a study to evaluate the effects and the safety of locally applied mitomycin C (MMC) on epidural fibrosis after microendoscopic discectomy (MED). Methods Seventy-five patients undergoing single-level unilateral MED for lumbar disc herniation were randomly assigned to receive cotton wool impregnated with either 0.5 mg/ml MMC or saline applied at the site of discectomy for 5 minutes. Outcome measures included degrees of pain severity, functional disability, physical symptoms, and quantitative evaluation of postoperative epidural fibrosis shown on follow-up lumbar contrast-enhanced MRI. Results Sixty-two patients completed the follow-up. Neither serious drug adverse effects nor clinically significant laboratory adverse effects were observed. Patients in both groups showed similar clinical recoveries postoperatively. A statistically significant difference (p < 0.05) between the 2 treatments was shown in a quantitative evaluation of postoperative MRI-documented epidural fibrosis in the MMC group and the saline group using a modified grading system. The mean cross-sectional areas of epidural fibrosis were 7.32–70.06 mm2 in the MMC group and 22.94–90.48 mm2 in the saline group. The epidural fibrosis index ranged from 0.0296 to 0.3267 in the MMC group and from 0.1191 to 0.3483 in the saline group. A significant difference was also observed using the Ross grading system to evaluate postoperative MR images. Conclusions Although no benefit was observed clinically, the authors observed a notable reduction of epidural fibrosis after MED radiologically, with 0.5 mg/ml MMC locally applied and no clinical side effects. Clinical trial registration no.: ChiCTR-TRC-10001079 (http://www.chictr.org/cn/proj/show.aspx?proj=326).