Impact of zinc deficiency, anatomical types of the frontal muscle and subcutaneous adipose tissue thickness on the thermographic response after botulinum toxin type a injections: a secondary analysis of 126 patients

Emelyanova E.V., Kytko O.V., Kutin E.S., Moiseenko A.A., Nelipa M.V., Vasiliev Yu.L.

Uclinic LLC Medical Center, Volgograd, Russia
I.M. Sechenov First Moscow State Medical University, Moscow, Russia

Objective. To evaluate the effect of subcutaneous adipose tissue (SAT) thickness, frontal muscle type, and zinc concentration on the thermographic response after botulinum toxin type A injections in patients with facial wrinkles of the forehead and glabella.

Methods. A secondary analysis of prospective study data (n=126) was performed, including infrared thermography before injection, immediately after, and at 30 minutes, 14 and 30 days. Additional measurements were performed: SAT thickness using a caliper (classification: thin <5 mm, medium 5-10 mm, thick >10 mm), frontal muscle anatomical type according to Raveendran (Type 1-3), and serum zinc (in 84 patients). Endpoints were hyperthermia amplitude (ΔT) at point P7 (projection of the corrugator supercilii muscle) at 30 minutes and clinical effect duration (time to return of skin fold thickness to baseline).

Results. SAT thickness >10 mm was associated with a 2.1-fold increase in ΔT compared to thin SAT (p<0.01) and more prolonged hyperthermia (p<0.05). In patients with Type 3 frontal muscle (absence of fiber crossover in the center), hyperthermia at point P7 was absent in 81% of cases, despite correct botulinum toxin type A injection technique.

Zinc deficiency was found in 31% of examined patients; in this group, clinical effect lasted 23% less (p<0.05), while early thermographic response did not differ from the group with normal serum zinc levels. Zinc-containing therapy prolonged therapeutic effect by 20% (p<0.05).

Conclusion. The thermographic response to botox therapy is significantly modified by SAT thickness, frontal muscle anatomy, and serum zinc level. Consideration of these factors enhances the diagnostic value of thermography and enables personalized interpretation of results.