Efficacy and safety of botulinum toxin injection in reducing deltoid muscle hypertrophy.

With the increasing demand for body contouring, botulinum toxin (BTX) injection is being widely used off-label for muscular hypertrophy. However, to the best of our knowledge, no study has investigated the clinical efficacy of BTX type A (BTX-A) in deltoid muscle hypertrophy. This study was conducted to evaluate the efficacy and safety of intramuscular injection of BTX in reducing deltoid muscle hypertrophy. Overall, 10 patients with bilateral deltoid muscle hypertrophy were treated with an intramuscular injection of prabotulinum toxin A, with a total of 50 units [U] administered per patient. As measured by ultrasonography, the thickness of the deltoid muscles was significantly decreased at weeks 2 and 12. In addition, the clinical assessment score by blinded investigators was improved after the treatment; however, patients' satisfaction scores were relatively low. No major complications were reported. Therefore, intramuscular injection of BTX-A seems to be a candidate for novel treatment option for deltoid muscle hypertrophy. Further larger clinical studies are warranted to confirm the efficacy of BTX-A.

A Double-Blinded, Randomized, Dose-Comparison Pilot Study to Comparatively Evaluate Efficacy and Safety of Two Doses of Botulinum Toxin Type A Injection for Deltoid Muscle Hypertrophy.

BACKGROUND: Botulinum toxin type A (BTX-A) injection is being widely used off-label for muscular hypertrophy, including deltoid muscle hypertrophy. However, very few studies have evaluated the optimal dosage and its clinical response. OBJECTIVE: This study aimed to assess the efficacy and safety of different doses of Prabotulinum toxin A (PBoNT) for treating deltoid muscle hypertrophy. METHODS: Twelve particiapants with bilateral deltoid muscle hypertrophy were enrolled and randomly received either 16 U or 32 U of PBoNT. In each participant, the same dose was administered to both deltoid muscles. Both participants and evaluators were blinded. Deltoid muscle thickness and upper arm circumference were measured on day 0, and weeks 2, 4, and 12 after the PBoNT injection. RESULTS: Upper arm circumference significantly decreased in both groups; however, deltoid muscle thickness was reduced in the 16 U group only. No major complications were reported in both groups. However, a few minor complications were reported in the 16 U injection group. CONCLUSION: Both 16 U and 32 U of PBoNT intramuscular injections are safe and effective in treating deltoid hypertrophy.