Consideration of muscle mass in glabellar line treatment with botulinum toxin type A.

The introduction of botulinum neurotoxin type A (BoNTA) for the treatment of glabellar lines marked a revolution in aesthetic medicine, allowing for noninvasive facial rejuvenation and sculpting. Treatment of the glabellar area requires a thorough understanding of facial anatomy and the interaction of adjacent muscle groups with respect to facial expression. Because the muscles underlying the glabella are among the larger muscles commonly treated with BoNTA, they may require higher doses than other facial sites. In addition, men typically have a greater glabellar muscle mass than women and require larger BoNTA doses. For optimal outcomes, it is necessary to account for individual variation in muscle mass, anatomy, and function to determine the proper dose, number, and location of injections. The validated Medicis Glabellar Muscle Mass Scale was developed to facilitate research on dose adjustment for muscle mass in the glabella and can be applied as a clinical tool. This review will discuss techniques for optimizing BoNTA treatment of the glabella, with emphasis on the need to assess muscle mass in individual patients and adjust BoNTA dosing and technique accordingly.