Analise dos elementos do tecido conjuntivo na resposta a injeção intrafascicular do anestesico ropivacaina em nervos ciaticos de coelhos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Persistent neurologic sequelae after central or peripheral nerve blockade with local anesthetics are rare, but in some cases a significant impact on the quality of life of the patients who suffer from such sequelae may occur. Experimental studies indicate that alI local anesthetics are potentially neurotoxin and the neurotoxicity paraIlels their anesthetic potency. This study was undertaken to investigate the effects of ropivacaine (Naropin) after intrafascicular injection into the sciatic nerves of albino rabbits. Twenty adult albine rabbits were used, following sedation with intramuscular ketamine (50mg!Kg) for nerve exposure by lateral incision. We considered three experimental groups: Group 1: sciatic nerve control (two animals four sciatic nerves); Group 11: intrafascicular injection with 0.2 mL of physiologic saline solution in the left nerves and intrafascicular injection with 0.2 mL of local anesthetic Naropin - Astra (Ropivacaine) into the rigth nerves. The specimens were colected at 48 h after durgs administration (nine animals - 18 sciatic nerves); Group111: intrafascicular injection with 0.2 mL of physiologic saline solution in the left nerves and intrafascicular injection with 0.2 mL of local anesthetic Naropin ? Astra (Ropivacaine) in the rigth nerves. The specimens were colected at 7 days after drugs administration. (nine animals - 18 sciatic nerves) The sciatic nerves were removed from these animals and fixed in Karnowisky solution for 24 hours. After partial dehydration up to 95% ethanol, they were embedded in historesin (Leica). The tissue was then sectioned at l-211m. Sections were stained with haematoxylin-eosin (HE); toluidine blue (TB) or picrosirius-haematoxylin (pSH). Comparing with control group the histological evidence of inflamatory reaction (migration of macrophagic cells and eosinophils - appeared soon after injection, with intense proliferation of perineurial cells. The results show that after 7 days of intrafascicular injection there was a severe fibrosis and an increase on perineurial vascularization. In group 2 the inflamatory reaction was noted near the local of the injection. Furthermore in this experiment we observed an increase on the number of epineurial lipoblasts and adipocytes. This study demonstrated that the toxic effects of ropivacaine are transient. In many cases there was an initial fascicular recover and axonal regeneration after 7 days of the injection

ASSUNTO(S)

tecido conjuntivo nervo ciatico anestesia local

ACESSO AO ARTIGO

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