Laryngeal photobiomodulation: application sites, interferences from body mass index and skin phototype.
Elisa Meiti Ribeiro Lin Plec, Viviane Souza Bicalho Bacelete, Marco Aurélio Rocha Santos and 1 others
PMID 39109706WHAT IT FOUND
Red laser light reliably reached the vocal fold front and cricothyroid muscle in all participants, but body fat reduced light intensity while darker skin increased it.
This suggests clinicians must adjust laser settings based on patient anatomy.
Key findings
01Laser application at the neck midline and 1 cm lateral consistently reached the anterior vocal fold and thyroarytenoid muscle in all participants.
02Higher body mass index reduced the intensity of light reaching the larynx, whereas darker skin phototypes increased the visualized light intensity.
03Application points lateral to the thyroid cartilage or above the thyroid notch failed to reach the target vocal fold structures in most participants.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study included only 15 women, so results cannot be generalized to men or children. All participants had healthy voices, so it is unknown if anatomical differences in patients with laryngeal pathology would change light penetration. The researchers visually judged the brightness of the light inside the larynx, which is subjective and not a precise measurement of energy delivered to the tissue. The study did not test whether the light reaching the tissue actually produced a biological effect or improved voice outcomes.
Declared interests
Funded by the National Council for Scientific and Technological Development (CNPq) in Brazil. No commercial conflicts of interest are reported.
The easy way to misread this
Do not assume that visible light inside the larynx means the treatment is effective or that the dose is correct. This study only confirmed that light could be seen reaching the area; it did not measure the actual energy absorbed by the muscles or test any voice improvements.