Polycaprolactone/Polylactic Acid Membrane Fails to Prevent Laminectomy-induced Sprouting of CGRP- and SP-immunopositive Nerve Fibres in the Dura mater lumbalis of Rats.

Abstract

Mechanisms and prevention of failed back surgery syndromes are rarely known in the clinical context. It has been shown that laminectomy induces outgrowth of putative nociceptive peptidergic afferents in the dura mater lumbalis of rats. We aimed to investigate whether the application of a polycaprolactone/polylactic acid membrane (Mesofol) after surgery inhibits sensory hyperinnervation. Adult Lewis rats were assigned to three groups: Control (no manipulation), Laminectomy and Laminectomy + Mesofol. Six weeks post-surgery, the durae were removed, immunohistochemically stained for CGRP- and SP-positive afferents and their density quantified. In controls, CGRP- and SP-positive neurons were predominantly found in ventral but rarely observed in dorsal parts of the dura. Following laminectomy, the density of afferents significantly increased ventrally, resulting in a dense network of nerve fibers. In dorsal regions, neuronal sprouting of was observed. Covering the dura with Mesofol after laminectomy had no impact on nerve fibre outgrowth. Application of Mesofol neither prevents nor significantly diminishes the laminectomy-induced increase in the density of peptidergic afferents.