Subclinical effects of botulinum toxin A and microwave thermolysis for axillary hyperhidrosis: A descriptive study with line‐field confocal optical coherence tomography and histology

Abstract

Botulinum toxin A (BTX) and microwave thermolysis (MWT) are standard axillary hyperhidrosis treatments, but comparison of their subclinical effects is lacking. Line‐field confocal optical coherence tomography (LC‐OCT) is a promising non‐invasive imaging tool for visualizing tissue‐interactions. This study aimed to describe subclinical effects of BTX and MWT for axillary hyperhidrosis with LC‐OCT‐imaging compared to histology. This study derived from an intra‐individual, randomized, controlled trial, treating axillary hyperhidrosis with BTX versus MWT. Subclinical effects based on LC‐OCT images from baseline and 6‐month follow‐up (n = 8 patients) were evaluated and compared to corresponding histological samples. At baseline, LC‐OCT visualized eccrine pores at the skin surface and ducts in the upper dermis (500 μm), but not deeper‐lying sweat glands. Histology identified entire sweat glands. Six months post‐treatment, LC‐OCT revealed no detectable morphology changes in any BTX‐treated axillae (100%), while recognizing obstructed eccrine pores and atrophy of eccrine ducts in most MWT‐treated axillae (75%). Histology corroborated LC‐OCT findings, while also showing substantial changes to entire sweat glands. LC‐OCT enabled visualization of subclinical alterations of superficial eccrine ducts after MWT and unchanged morphology after BTX. LC‐OCT is a promising tool for non‐invasive assessment of treatment‐specific tissue‐interactions that can be complementary to histology.