The effect of methylprednisolone and tenoxicam on the protection of damage of the nerve physiomorphology caused by prolene mesh.

Introduction: Aim was to investigate the effect of methylprednisolone and tenoxicam on the protection of damage of the nerve physiomorphology caused by prolene mesh used in hernia repair.
Methods: Fifty male Wistar-albino rats weighing 250-350 gr, were randomly divided into 5 groups. Sciatic nerve was dissected in all rats after performing EMG on basal neural transport. In group 1, only sciatic nerve manipulation was performed. Other groups received a monofilament polypropylene cuff around the sciatic nerve. No additional procedure was performed in group 2. In group 3, 2 mg/kg single dose methylprednisolone was injected around the nerve and mesh. In group 4 and 5, 0.5 mg/kg/day methylprednisolone and 1 mg/kg tenoxicam was injected around the nerve and mesh for 4 weeks, respectively. Neural transport was evaluated by electromyography 4 weeks later and compared with pre-procedural values. Then the rats were sacrificed and, sciatic nerves including 1 cm around the mesh were excised. Inflammation and fibrosis were scored histopathologically.
Results: While basal latency was similar, postoperative latency was significantly different among groups. Latency was significantly longer in group 2 than the group 1. It was significantly shorter in group 3 when compared to group 2 (p = 0.007). Preoperative and postoperative amplitudes were similar among groups. Denervation was significantly different among groups (p < 0.05). Denervation was higher in group 2 than group 1. It was similar to group 2 in study groups. Inflammation and fibrosis was significantly different among groups (p < 0.05). Inflammation and fibrosis scores were significantly higher in group 2 than group 1. The highest inflammation and fibrosis scores were detected in repetitive drug administrated groups. Although it wasn't statistically significant, inflammation was lower in single dose steroid administrated group than group 2. Similarly, the highest fibrosis scores were detected in repetitive drug administrated groups. Single dose steroid administration didn't increase fibrosis when compared to group 2.
Conclusions: Prolene mesh used in hernia repair caused increased inflammation and fibrosis and effected latency and denervation negatively. Single dose methylprednisolone administration decreased nerve damage and inflammation. On the other hand, daily administration of methylprednisolone and tenoxicam for 4 weeks caused increased inflammation and fibrosis and wasn't affective on protection of nerve physiomorphology.
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