Three Dimensions of Precision in LetibotulinumtoxinA Treatment: Dose, Dilution and Injection Pattern in Relation to Diffusion

Botulinum neurotoxin type A (BoNTA) is widely used for the treatment of dynamic facial wrinkles, where precise control of toxin diffusion is essential to achieve predictable aesthetic outcomes while preserving natural facial expression. However, the relative influence of injection pattern, dose, and dilution on diffusion characteristics remains incompletely understood. In this exploratory case series, treatment-naïve subjects undergoing aesthetic treatment of horizontal forehead lines with LetibotulinumtoxinA (Leti-BoNTA) were assigned to one of four injection paradigms according to their wrinkle pattern: a conventional five-point injection pattern, the previously published LEBO injection pattern, dose variation (2–5 U per injection point), or dilution variation (reconstitution volumes 0.675–2.5 mL). Diffusion was assessed using the Minor iodine–starch test, and anhidrotic areas were quantified in cm2. Increasing dose was associated with progressively larger anhidrotic areas in this exploratory case series. Greater reconstitution volumes were associated with broader toxin distribution, whereas lower dilution volumes produced more confined diffusion areas. The conventional five-point injection pattern resulted in relatively extensive diffusion, whereas the LEBO protocol demonstrated a more localized and consistent distribution profile. Despite differences in diffusion characteristics, natural facial dynamics were preserved across all treatment paradigms. These findings suggest that injection pattern, dose, and dilution collectively influence Leti-BoNTA diffusion and should be considered when optimizing individualized treatment strategies.