gms | German Medical Science

Objective: Extensive epidural fibrosis after lumbar spine surgery may be the underlying cause for disabling low back pain radiating in the leg, the so called “failed back surgery syndrome”. In the last decades, a large variety of materials and substances has been used to prevent epidural fibrosis, however the results of these studies showed only moderate success. Rapamycin, first isolated from the soil bacteria Streptomyces hygroscopicus, is a potent immunosuppressant. In this study, we investigated the effect of Rapamycin by local application on spinal epidural fibrosis and dural adhesions in a rat laminectomy model.

Methods: 14 adult Wistar rats underwent a lumbar laminectomy exposing the dura mater. In 7 rats, Rapamycin was locally applied to the laminectomy sites in concentration of 0.1 µg/ml. No treatment was performed in another 7 rats. All rats underwent clinical evaluation. Mobility status and evidence of neurological deficit were recorded. Twelve weeks after laminectomy, histological analysis was performed. The extent of epidural fibrosis and density along the dura mater and dural adhesions were evaluated.

Results: Postoperatively, all rats were healthy and without neurological deficits. There was no case of wound infection or disturbance of wound healing. Histological evaluation of the laminectomy sites showed that in all Rapamycin-treated laminectomy sites, epidural scarring was significantly reduced and dural adhesions were absent or discrete in comparing with control sites. All control sites showed dense epidural fibrosis with marked dura adherence.

Conclusions: In this experimental model, Rapamycin applied locally at a concentration of 0.1 µg/ml effectively reduced epidural fibrosis, largely avoided dural adherence, and induced no side effects.