QUANTIFYING HOW LOCATION AND DOSE OF BOTULINUM TOXIN INJECTIONS AFFECT MUSCLE PARALYSIS

Despite the widespread use of botulinum toxin to treat muscle dystonia s, no method exists to quantify muscle paralysis in either human or no nhuman models. In this study we examined how the location, dose, and v olume of botulinum injection affects paralysis in the rat tibialis ant erior muscle. Paralysis was quantified by electrically stimulating the nerve to the tibialis anterior and then staining sections of the musc le for glycogen. The areas of glycogen-containing fibers represented r egions of botulinum action. The results showed that the most important injection technique is to inject botulinum directly into the motor en dplate region of a muscle. Injections only 0.5 cm from the motor endpl ate resulted in a 50% decrease in paralysis. Increases in dose increas ed paralysis, however, some of that increase was simply due to the inc reased volume of injection. Thus, delivering toxin in small volumes ne ar the MEP band of a muscle should produce the most effective paralysi s. (C) 1993 John Wiley & Sons, Inc.