Introduction: Microflap is a commonly performed phonomicrosurgical technique for the removal of vocal fold lesions. Although previous studies demonstrated rapid functional recovery and stratified epithelia within 7 days, immune cell recruitment, permeability changes, and downregulation of cellular junction proteins were identified in preclinical models of vocal fold injury. In the current study, we investigated epithelial physiology following microflap via: transepithelial electrical resistance (TEER), paracellular space dilation, and immune cell infiltration.
Methods: Forty New Zealand white rabbits were assigned to 8 groups; no-injury control, and survival for 0 hours, 12 hours, 1 day, 3 days, 7 days, 30 days, and 60 days post-microflap (n=5 per group). The epithelium was dissected from one vocal fold and TEER was quantified using an Ussing Chamber. The second vocal fold was fixed, osmium-tetroxide processed, resin embedded and ultrathin sectioned. Ultrathin sections were imaged by transmission electron microscopy at x8000 and x20000 and evaluated by a blinded rater. Paracellular space dilation was quantified using ImageJ. Immune cell infiltration was evaluated from x8000 images and recorded qualitatively.
Results: Increased innate immune responses were identified at 12 hours and at 7- and 30-days post-surgery. Dilated paracellular spaces were observed up to 60 days and reduced TEER was sustained 60 days post-microflap.
Conclusions: The vocal fold epithelium did not return to baseline within 60 days of surgical microflap procedure. Future studies will focus on preclinical investigation of therapeutic approaches to optimize vocal fold healing as well as the functional implications for compromised vocal fold barrier function.