Digital Kymography Evaluation of Women With Behavioral Dysphonia Undergoing Low-Level Laser Photobiomodulation

To evaluate the immediate effect of laryngeal photobiomodulation using a 9-J low-level laser (LLL) combined with the voiced tongue trill technique (VTTT) in women with behavioral dysphonia, using digital kymography (DKG) analysis.

This experimental randomized clinical trial included 30 women with behavioral dysphonia and changes in laryngeal examination, divided into two groups (placebo and experimental). High-speed videolaryngoscopy (HSV) was performed before and after laser application at points corresponding to the intrinsic laryngeal muscles. The placebo group (G1) underwent laser application without the use of light, combined with VTTT for 5 minutes. The experimental group (G2) underwent photobiomodulation at 9 J and performed VTTT for 5 minutes. Participants underwent HSV before and immediately after laser application. The images were transformed into DKG and analyzed with quantitative parameters in the anterior, middle, and posterior thirds of the vocal folds.

The intergroup (G1 and G2) evaluation found a statistically significant difference in the middle glottic third at maximum opening (MaxOp), mean opening (MeanOp), and DKG index before intervention. The postintervention evaluation found changes in MaxOp in the anterior, middle, and posterior thirds between G1 and G2 and MeanOp variations in the middle and anterior thirds. G2 had an increase in MeanOp in the anterior third after the intervention.

Applying photobiomodulation with LLL associated with VTTT immediately changed the larynx during its phonatory phase, demonstrated by the increase in MeanOp in the anterior third of the vocal folds. Studies with HSV and DKG should select more homogeneous groups to evaluate therapeutic interventions.