Clinical and histological evaluation of a single high energy microwave treatment for primary axillary hyperhidrosis in Asians: A prospective, randomized, controlled, split-area comparative trial.

Background and Objectives Microwave treatment is an effective non-invasive treatment option for primary axillary hyperhidrosis (PAH), but the treatment parameters vary and no histopathological studies have been performed to validate clinical outcomes. This study investigated its efficacy and safety and histopathological changes after a single microwave treatment at the maximum energy level for PAH in Asians. Materials and Methods A prospective, clinical, and histological split-area randomized controlled trial (RCT) was performed in Japan. Twenty-six subjects underwent a single microwave treatment at the maximum energy level 5 (5.8 GHz/axilla) on the randomized side of axillae. The primary outcome was the mean difference between both sides in the improvement of modified single-underarm Hyperhidrosis Disease Severity Scale (msHDSS) scores over the course of the 12-month study period from baseline. The secondary outcomes were; the percentage of responders with at least a 2-point drop in the msHDSS score of 3 or 4 group or with a 1-point drop in the msHDSS score of 2 group; the percentage of responders with at least a 75% reduction in sweat weight over 12 months; recurrence rate; and adverse effects. We also performed a histological assessment for 13 selected subjects. Results Twenty-four subjects completed the study. There were statistically significant differences in improvement of msHDSS scores between the microwave-treated and control sides (P < 0.05) from baseline at 0.5, 1, 3, 6, and 12 months. In the msHDSS score of 3 or 4 group, the percentage of responders with at least a 2-point drop on the microwave-treated side versus control side was 72.2 versus 11.1% (P < 0.05) at 1 month, 83.3 versus 5.6% (P < 0.05) at 3 months, 61.1 versus 38.9% (P = 0.317) at 6 months and 38.9 versus 16.7% (P = 0.264) at 12 months. The percentage of responders with at least a 75% reduction in sweat weight on the microwave-treated side versus control side was 75.0 versus 37.5% at 1 month, 75.0 versus 29.2% at 3 months, 83.3 versus 50.0% at 6 months and 70.8 versus 33.3% at 12 months (all P < 0.05). Recurrence on the microwave-treated side was observed in 4.2% and 12.5% of 24 subjects at 3 and 12 months, respectively. No serious side-effects were noted. Histology showed the diameter and density of secretory eccrine glands and nerve fiber lengths around eccrine glands were significantly decreased after treatment compared to baseline (P = 0.002, 0.027, 0.003, respectively). Conclusions A single-session microwave treatment at the maximum energy level significantly improved the PAH of Japanese patients and had minimal side effects. This technique demonstrates that diminished size of secretory eccrine glands and nerve fiber degeneration could be useful markers for predicting the efficacy of the treatment. Lasers Surg. Med. 9999:1-8, 2019. (c) 2019 Wiley Periodicals, Inc.