Neural Distribution-Guided Botulinum Toxin Injection for Platysma muscle: A Split-Neck Comparison With Conventional Technique.

[BACKGROUND] The platysma muscle plays a pivotal role in the formation of vertical neck bands and contributes to lower facial descent, making it a prime target for botulinum toxin type A (BoNT-A) in aesthetic neck rejuvenation. Conventional protocols typically involve injecting across the entire muscle, necessitating a high number of injection points and larger total doses, which may increase the risk of bruising, patient discomfort, and potential immunogenicity. Recent anatomical studies using Sihler's staining have demonstrated that motor innervation is predominantly concentrated in the upper portion of the platysma.

[AIMS] To evaluate a neural distribution-based BoNT-A injection strategy targeting only the motor-rich upper platysma, compared with the conventional whole-muscle injection approach.

[METHODS] Fifteen patients with prominent platysmal bands received BoNT-A injections (JETEMA THE TOXIN, JETEMA Inc., Korea) in a split-side design: The right platysma was injected using a conventional 30-point technique, and the left platysma received 15 targeted injections in the upper portion based on mapped motor entry points. Efficacy was assessed by the degree of platysmal band relaxation at follow-up.

[RESULTS] Both techniques achieved comparable improvement in platysmal band appearance, despite the targeted side requiring 50% fewer injection points.

[CONCLUSIONS] Motor innervation-guided BoNT-A injections may achieve equivalent clinical outcomes while reducing injection burden, toxin dose, and complication risk.