Effects of epidural steroids on lumbar dura material properties

Epidural steroid injections are commonly used in the treatment of low back pain and radiculopathy based on their antiinflammatory and analgesic benefi ts. However, steroids are known to affect collagen synthesis, material stre ngth, and tissue healing. The purpose of this study was to assess the effec ts of serial epidural steroid injections on the material properties of the lumbar dura mater. Serial epidural steroid injections of saline or methylpr ednisolone at 2-week intervals were performed in three paired groups of can ines; a separate noninjected group was used as controls. Postmortem, dural sample testing to failure and histologic analysis was performed. Mechanical failure testing revealed no clinically significant change in the transvers e dorsal dura tensile strength between all saline-injected, steroid-injecte d, or noninjected controls. Histologic analysis demonstrated no overt disru ption of collagen matrix organization; however, electron microscopy demonst rated a significant decrease in the number of intracytoplasmic mitochondria of dural fibroblasts in steroid-injected animals, suggesting a metabolic i nhibitory effect within steroid-injected dura mater. In the clinical time f rame of this study, serial epidural steroid injections appeared to produced no significant material or matrix changes in the lumbar dura.