Real-time light-guided vocal fold injection: An in vivo feasibility study in a canine model.

Purpose The trans-cutaneous approach is a good option for office-based vocal fold injection (VFI). However, precise localization requires a high level of experience because the needle tip is invisible in small and complex laryngeal spaces. Recently, a new technique, real-time light-guided VFI (RL-VFI), was proposed; it allows simultaneous injection under precise needle localization by light guidance. Herein, we aimed to verify the feasibility of RL-VFI in an in vivo canine model and tried to explore its clinical usefulness. Methods The device for RL-VFI comprised the light source (light-emitting diode modules [10W] of red color [650nm]) and the injectors (1.5 inches, 23 gauge). An adult male beagle was used for the experiment. After tracheostomy, a rigid laryngoscope was inserted and suspended to expose the larynx. A flexible naso-laryngoscopy system was used to visualize the vocal folds. Results RL-VFI was performed using various trans-cutaneous approaches, including cricothyroid (CT), trans-thyroid (TT), and trans-hyoid (TH) approaches. Light guidance helped identify the path of the needle and prevent inadvertent penetration. The location of the needle tip was accurately indicated by the light. The lighted needle could be easily placed at the intended points in the vocal fold with real-time visual-motor feedback. Hyaluronic acid could be simultaneously injected lateral to the vocal process under light guidance without manipulation of the device. Conclusion RL-VFI is safe and feasible in an in vivo canine model, providing precise localization and visual-motor feedback. The clinical application of RL-VFI is expected to improve safety and precision in VFI.