Optimizing Botulinum Toxin Injections in the Platysma Muscle Based on Motor Nerve Distribution

ABSTRACT Background Platysmal bands contribute to neck ageing and lower‐face descent. Although botulinum toxin A (BoNT‐A) is approved for this indication, conventional whole‐muscle dosing requires many superficial injections with attendant risks. Objective To develop an anatomically guided protocol that targets motor‐dense zones of the platysma, optimizing efficacy while reducing dose and complications. Methods Sihler‐stained dissections mapped motor versus sensory innervation. Ultrasound‐guided injections were performed in 40 patients, delivering 30–60 U BoNT‐A per side at 15 sites concentrated in the upper two‐thirds of the platysma and along the marginal mandibular border. Outcomes included band severity, jawline definition, adverse events, and cost. Results Motor end‐plates clustered in the upper platysma; the lower third was largely sensory. Targeted injections produced a ≥ 2‐grade reduction in dynamic bands in 92.5% of patients by week 4, maintained through week 12. Mean toxin use fell 35% versus historical whole‐muscle protocols; bruising dropped to 5%, with no dysphagia or lower‐face weakness. Treatment costs were proportionally lower. Conclusions Concentrating BoNT‐A in the motor‐rich upper platysma under ultrasound guidance maximizes aesthetic improvements while minimizing dose, discomfort and adverse events. This neural distribution‐based algorithm offers a safer, more economical alternative to conventional platysmal band treatment.