There are two parts to this study. In the first part, all study participants will receive treatment with an intramuscular injection of 30 Units of Mentor Purified Toxin on two separate occasions (Cycles 1 and 2) no more than 6 months apart. In the second part of the study (Cycle 3), subjects will be randomly assigned to receive either intramuscular injections of 30 Units of Mentor Purified Toxin or placebo (preservative-free saline) and subjects will be followed for 1 month (3:1, PurTox : placebo).