Line-Field Confocal Optical Coherence Tomography Offers Non-Invasive Assessment of Subclinical Features and Treatment Interactions

Line-field confocal optical coherence tomography (LC-OCT) is capable of providing non-invasive assessment of tissue interactions in hyperhidrosis, according to research published in Experimental Dermatology.¹

Researchers found that LC-OCT was able to identify and support the presence of changes as a result of treatment with botulinum toxin (non-structural changes) or microwave thermolysis (irreversible tissue damage).

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Background and Methods

Previous studies have relied on histological samples to explore subclinical changes resulting from various procedures.²

However, according to researchers, the invasive and scarring nature of histological sampling limits its usefulness for continuous monitoring, especially in delimited treatment areas like the axillae. They described a need to explore the potential of recently developed imaging devices for real-time, non-invasive assessment of treatment effects.

To the knowledge of researchers, the role of LC-OCT-imaging in axillary hyperhidrosis, specifically with regard to its ability to compare tissue interactions following treatment with botulinum toxin or microwave thermolysis, has not previously been explored.

This study, conducted between 2021 and 2023, delved into the efficacy of botulinum toxin versus microwave thermolysis for the treatment of axillary hyperhidrosis. Researchers conducted a substudy within the overarching trial, aiming to explore subclinical outcomes through LC-OCT imaging and histological analysis.

Participants of the substudy, recruited on a voluntary basis, consented to undergo LC-OCT imaging and biopsies from each axilla at baseline and again at the 6-month mark post-treatment. Participants were enrolled in the substudy before treatment randomization to ensure unbiased outcome assessment.

To maintain consistency in imaging, researchers utilized a transparent template with positioned cut-out holes. Each hole underwent LC-OCT imaging both at baseline and the 6-month follow-up, with all images assessed by a physician proficient in LC-OCT interpretation.

Complementing LC-OCT imaging, histological samples were gathered and biopsies, 4mm in size, were obtained from each axilla at baseline and at 6-months post-treatment.

Findings

The study encompassed a total of 16 axillae from 8 patients. LC-OCT images and biopsies were collected from each axilla at baseline and after 6 months, with botulinum toxin treatment administered to 1 axilla and microwave thermolysis to the contralateral axilla.

After 6 months, LC-OCT revealed no discernible alterations in eccrine duct morphology in botulinum toxin-treated axillae, corroborating histological findings of no significant changes compared to baseline.

Conversely, The study encompassed a total of 16 axillae from 8 patients. LC-OCT images and biopsies were collected from each axilla at baseline and after 6 months, with botulinum toxin treatment administered to 1 axilla and microwave thermolysis-treated axillae exhibited obstructed pores and atrophic eccrine ducts in the majority of cases. Histologically, there was a reduction in sweat gland density, atrophy of eccrine glands, and surrounding fibrosis post-microwave thermolysis.

Conclusions

These findings may support the capability of LC-OCT to evaluate treatment effects via in-vivo assessment.

"In comparison to the limited resolution of traditional Optical Coherence Tomography, LC-OCT provides a detailed visualization of eccrine gland structures," according to study authors Grove et al.

In the future, researchers suggested that machine learning applied to larger datasets may improve the ability to identify unclear features. Moreover, quantitative data analysis could be enhanced through pattern recognition on LC-OCT video-function data. Future real-time, non-invasive imaging should aim to minimize sampling errors and non-representative biopsies.

References

1. Grove GL, Jacobsen K, Maartensson NL, Haedersdal M. Subclinical effects of botulinum toxin A and microwave thermolysis for axillary hyperhidrosis: A descriptive study with line-field confocal optical coherence tomography and histology. Exp Dermatol. 2024;33(6):e15110. doi:10.1111/exd.15110
2. Kaminaka C, Mikita N, Inaba Y, et al. 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. Lasers Surg Med. 2019; 51(7): 592-599. doi:10.1002/lsm.23073