Low or High Botox Dilution for the Hemiplegic Gait?

Overview

There is debate regarding the efficiency of different dilutions of Botulin toxin type A (BTX-A) injections. Some authors believe that highly diluted BTX-A injections achieve greater neuromuscular blockade resulting in higher spasticity reduction. On the other hand, other researchers suggest that there is no difference in spasticity decrease if either high or low volume toxin is being injected. Studies on this subject lack either the design or the power of study was low. Therefore, there is no clear guideline for an optimal botulinum toxin dilution protocol. In an attempt to have a better understanding, a cross over study was designed. The material will be patients with spastic hemiparesis which will be treated with Botulin toxin at different dilutions. Gait analysis will be used for the evaluation of the Botulin toxin injection on gait improvement. To the best of our knowledge such a trial hasn't been performed yet.

There is an ongoing controversy regarding the effect of different dilutions in the efficacy of Botulin toxin type A (BTX-A) injections. Some authors believe that highly diluted BTX-A injections achieve greater neuromuscular blockade resulting in higher spasticity reduction. They are arguing that BTX-A in high dilution is the optimal choice especially when bigger muscles are injected, for the large volume of fluid administered into the muscle will carry the BTX-A molecules to endplates remote from the injection site. Two animal studies suggest that increasing the volume of diluents is a potential strategy in order to achieve a more efficient and cost-effective manner of BTX-A treatment. An attempt to quantify how the location of BTX-A injection affects the drug effect was made, which revealed that injecting only 0.5 cm away from the motor endplates yielded a 50% decrease in paralysis2. A newer double-blinded study by JM Gracies et al performed on humans comes to the same conclusion, that high volume dilution provides greater neuromuscular block and spasticity reduction than a low volume dilution. On the other hand, other researchers suggest that there is no difference in spasticity decrease if either high or low volume toxin is being injected. Previous studies lack either the design or the power of study was low. Therefore, there is no clear guideline for an optimal botulinum toxin dilution protocol.