| Objective To verify the dose-response relationship in alcohol-induced rabbits'tibial nerve block and to determine the volume of alcohol injectate required for effective conduction block.Method Twenty-four New Zealand white rabbits were selected for experiment and randomly assigned to four groups based on alcohol volume (0.1ml,0.3ml,0.5ml,1.0ml). All tibial nerves were successfully located with a nerve electrical stimulator. Compound muscle action potential (CMAP) was measured preintervention and at days 1, 2, 4, 7 and weeks 2, 3, 4, 5, 6, 7, 8 postblock on the skin surface of the gastrocnemius muscle belly. Histologic studies were performed to evaluate the destruction of the tibial nerves and muscle.Results The interaction of time and volume groups was existed (P<0.001). In four groups, CMAP amplitude showed reduction 1 day after nerve block. In group 0.1ml, CMAP amplitude showed the smallest reduction at 1 day and recovered in 1 week after block, but the block effect disappeared at 2 weeks (P>0.05). But in group of 0.3ml the block effect last 8 weeks. In groups of 0.5ml and 1.0ml, CMAP amplitudes showed maximal reduction 1 day and no increase after block 4 weeks. There was no statistically difference between the volume groups 0.3ml and 0.5ml (P<0.05). Axonal degeneration was evident within the tibial nerve among all groups. Muscle desmoplasia was noted within the groups of 0.5ml and 1.0ml.Conclusion The most effective and safest volume is 0.3ml for alcohol induced rabbits'tibial nerve block.
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