Injection Mapping and Dose Escalation For Botulinum Toxin Treatment on the Lower Face: A Randomized, Double-blind Clinical Trial.

BACKGROUND: Facial lifting with botulinum toxin in the lower face results from modulation of the balance between depressor and elevator muscles. Injection strategies typically describe dose and point distribution, although these parameters may reflect the extent of neuromuscular modulation across the treated area. OBJECTIVES: To evaluate the effect of increasing treatment extent in lower face neuromodulator applications on tissue displacement, patient-reported outcomes, and tolerability. METHODS: Eighty patients were allocated to four treatment groups differing in the number and distribution of lower-face injections targeting the platysma and depressor anguli oris muscles. Outcomes were assessed at 15, 30, and 90 days using 3D stereophotogrammetry, Global Aesthetic Improvement Scale (GAIS), and FACE-Q Satisfaction with Outcome and Adverse Effects modules. Associations with patient characteristics were also analyzed. RESULTS: All treatments produced measurable lifting effects. Greater treatment extent was associated with increased tissue displacement at 15 days (p=0.004) and greater persistence of displacement over time. Patient-reported outcomes followed a similar pattern, peaking at 30 days and remaining higher in intermediate-to-high extent groups. Adverse effects decreased over time but were higher in the most extensive group at 90 days (p=0.006). Multivariable analysis demonstrated a positive association between number of injection points and tissue displacement (β=1.875; p=0.040), and a negative association with BMI (β=-4.361; p=0.022). CONCLUSIONS: Lower-face neuromodulator treatments produce measurable lifting effects that scale with the extent of muscular coverage. Broader distribution enhances the magnitude and durability of tissue repositioning, although with a modest increase in perceived adverse effects. BMI may act as a response modifier.