Abstract PR336

Abstract

Background & Objectives: Peripheral nerve blocks are widely used in clinical practice in spite of neurologic complications which may be rare but may cause disabilities. So the studies about the protection from local anesthetic toxicity with an adjuvant agents still continue. We aimed to analyse a controversial drug; mannitol for this aspect (1,2). Materials & Methods: After the ethics committe approval, forthy rats were randomly assigned into four groups equally. After preoperative physical examination all animals were deeply anesthetized and right sciatic nerve exposed with mid-thigh incision. The drugs according to the groups were injected to the nerve extrafascicularly with a 30 gauged syringe and the wound was sutured in layers. Group 1, as a control group, received 0.4 mL saline; group 2 received 0.2mL 5% bupivacaine and 0.2mL saline combination; group 3 received 0.2mL 5% bupivacaine and 0.2mL dexamethasone combination; group 4 received 0.2mL 5% bupivacaine and 0.2mL 20% mannitol combination. After anesthesia recovery, animals were followed 14 days with motor functional capacity. At the end of the study period animals euthanized and sciatic nerves were excised for histopathological assessment with H&E staining. Histopathological analyses performed in terms of neuronal degeneration, intraneural and perineural inflammatory cells under light microscopy. Results: According to the histopathological findings intraneural or perineural inflammatory cells were not observed in group 1 and 2. In group 1 and 2, neuronal degeneration is minimal or none. There were no significant differences between group 3 and the first two groups in terms of histopathological findings. But in group 4, significant pathological findings were observed. Neuronal degeneration, intra and perineuronal inflammatory cells and perineural vascular proliferation were markedly increased in group 4. Conclusion: Steroids were used for different purposes eg. for their neuroprotective effects in different studies and had no side effects in cellular level. But mannitol is not a harmless adjuvant agent with its significant inflammatory and degenerative effects that detected by light microscopy. So it may not be recommended to use in peripheral nerve blocks in humans.