Efficacy of type A botulinum toxin treatment for androgenetic alopecia using ultrasound combined with trichoscopy.

[OBJECTIVE] This study aimed to assess the efficacy of type A botulinum toxin treatment for androgenetic alopecia (AGA) using a combination of ultrasound and trichoscopy.

[METHODS] Ninety patients with AGA who visited the Department of Dermatology at the Second Affiliated Hospital of Soochow University from September 2021 to December 2022 were prospectively selected. These patients met the diagnostic criteria outlined in the Chinese Guidelines for the Diagnosis and Treatment of Androgenetic Alopecia. The alopecia severity in the male patients ranged between grades 2 and 4 on the Norwood-Hamilton Scale. The patients were randomly assigned to receive injections of the same type of biological agent in a double-blind manner, with injection sites being the vertex or bilateral temporal-frontal hairline. In this study, the botulinum toxin group comprised 72 patients who received a biological agent with 100 units of type A botulinum toxin. The control group included 18 patients, and the biological agent administered to them contained 0 units of type A botulinum toxin. The patients were observed using 22-MHz ultrasound and trichoscopy before treatment, and 1 month and 3 months after treatment to compare the differences in various parameters at the injection sites. The ultrasound parameters included average follicle width, length, and count. The trichoscopy parameters were the number of hairs within a 1-cm area on the counting scale. No artificial interventions were performed at the injection sites, and all examination conditions were consistent.

[RESULTS] The patients in the botulinum toxin group had wider and longer average follicle width and length at the vertex 1 month and 3 months after treatment (p < 0.05), and wider and longer average follicle width and length in the left frontal area 3 months after treatment (p < 0.05) compared with those in the control group. The average follicle width and length gradually increased after treatment in the botulinum toxin group (p < 0.05), but no statistically significant differences were found in the control group (p > 0.05). The patients in the botulinum toxin group exhibited greater average follicle lengths after treatment at the vertex compared with the left frontal area (p < 0.05). No statistically significant differences were found in follicle count (p > 0.05) or hair count (p > 0.05) between the botulinum toxin and control groups after injection treatment.

[CONCLUSIONS] The follicle width and length are effective parameters for evaluating the efficacy of type A botulinum toxin treatment for AGA. Ultrasound revealed that the changes in follicles at the vertex occurred earlier than those in the left frontal area following treatment. Additionally, the changes in follicles were detected earlier than the changes in hair count using ultrasound. Ultrasound combined with trichoscopy provided more parameters for evaluating the efficacy of type A botulinum toxin treatment for AGA, resulting in a more comprehensive evaluation.