A model for 532-nanometer pulsed potassium titanyl phosphate (KTP) laser-induced injury in the rat larynx.

Objectives/hypothesis: The potassium titanyl phosphate (KTP) laser is emerging as a potentially effective treatment for various vocal fold pathologies. To date, the precise mechanism(s) of action of this wavelength on the layered microarchitecture of the vocal fold remains unknown. The purpose of this study is to develop an in vivo model for the use of the KTP laser in the rat vocal fold and to characterize the potential of this model for future studies.

Study Design: In vivo survival surgery.

Methods: A model for videoendoscopic visualization and injury to the rat vocal fold was established using a microlaryngoscope and rigid telescope. Unilateral vocal fold injury was induced with the KTP laser at 10 Watts (W) 20 milliseconds (ms) pulse width. Animals were euthanized at 1 day post-treatment. Larynges were subjected to gross visual analysis and histological analyses via hematoxylin and eosin and trichrome staining.

Results: Consistent endoscopic visualization and injury was obtained without significant operative morbidity or mortality. The KTP laser caused superficial blanching and minor edema in the vocal fold, which resolved grossly by 24 hours postinjury. A modest inflammatory cell infiltrate was observed 1 day following injury. However, no remarkable alterations to the vocal fold microarchitecture were observed in the acute period.

Conclusions: We propose that this novel model simulates the clinical scenario of laser use for the vocal folds. Use of this model will allow us to further characterize effects, mechanisms, and therapeutic efficacy of this wavelength.