Factors Influencing Injectate Spread After Alcohol Block Of Rabbits' Tibial Nerves

Objective:To explore the effects of different injection speed, concentration and volume on the feature of injectate spread and provide the basis for the clinical application of chemical neurolysis.Method:Fifty-four tibial nerves of rabbits were randomly assigned to speed group(SG,n=18), concentration group(CG,n=12)and volume group(VG,n=24). All tibial nerves were successfully located with a nerve stimulator and neurolyzed with a mixed solution of alcohol and contrast medium. The three subgroups of SG each received 0.3ml dehydrated alcohol at three different speed of injection(0.004ml/s,0.01ml/s,0.1ml/s).The two subgroups of CG each received 0.3 ml alcohol of different concentration (50%,100%) at the same speed of injection (0.01ml/s). The four subgroups of VG each received different volume of dehydrated alcohol (0.1ml,0.3ml,0.5ml,1.0ml) at the same speed of injection (0.01ml/s).After 10min of injection, helical CT scanning was performed to calculate the volume of injectate spread and evaluate its spread pattern by three-dimensional reconstruction.Result:The volume of alcohol spread of subgroup Ic was more than that in subgroup Ia and Ib (P<0.05).There was no statistically difference between the volumes of alcohol spread of the two subgroups of CG(P>0.05). The group VG demonstrated significant differences among subgroups of VG(P<0.05).Conclusion:Alcohol spreads longitudinally along the tibial nerve. The speed and volume except for concentration of injectate can significantly influence the volume of alcohol spread. So optimal volume should be chosen to increase the selectivity of nerve block and avoid unwanted blocking of adjacent nontarget nerves.