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

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 mm(2) in the MMC group and 22.94-90.48 mm(2) 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.