[Preventing and treating anterior commissure adhesion with mucosal flap: a study in canines and clinical cases]

Objective: To evaluate the effectiveness of mucosal flap combined with silicone keel for preventing and treating anterior commissure adhesion in canines and clinical cases. Methods: A prospective experiment was performed from November 2019 to June 2021. Twenty five canines were randomly divided into 5 groups(A, B, C, D, E). Group A, B, C, D received anterior commissure injury by CO₂ laser, then separately treated with free mucosal flap-keel complex,intralaryngeal mucosal flap-keel complex, silicone keels and without treatment, group E didn't injure the vocal cord after intubation. The keel was removed after 2 weeks, the larynx was harvested after 4 weeks. The effectiveness of anterior commissure adhesion prevention was evaluated by manifestation under laryngoscope, standard vocal cord length and standard glottic area. A retrospective analysis was performed on sixteen patients with anterior commissure lesion, who underwent mucosal flap-keel technique in Huashan Hospital of Fudan University from January 2019 to January 2021 (10 cases with free mucosal flap-keel complex and 6 cases with intralaryngeal mucosal flap-keel complex). All the patients underwent evaluation of laryngeal function included manifestation under laryngoscope each month and voice analysis before and 3 month after surgery. SPSS 20.0 software was used for statistical analysis. Results: No surgery accident or complication happened in canines and patients. The standard vocal cord length and standard glottic area after 4 weeks in group B were significantly higher than those in group A, C, D (H_{standard vocal cord length}=31.688, H_{standard glottic area}=16.444, P<0.05). The standard vocal cord length and standard glottic area after 4 weeks in group A were also significantly higher than those in group C, D(H_{standard vocal cord length}=20.936, H_{standard glottic area}=11.786, P<0.05). The standard vocal cord length and standard glottic area after 4 weeks in group A, B, E were not significantly different to that before surgery(t_{A left standard vocal cord length}=2.636, t_{A right standard vocal cord length}=2.582, t_{B left standard vocal cord length}=2.707, t_{B right standard vocal cord length}=2.673, t_{E left standard vocal cord length}=0.370, t_{E right standard vocal cord length}=0.821, t_{A standard glottic area}=2.731, t_{B standard glottic area}=2.753, t_{E standard glottic area}=-0.529, P>0.05). The standard vocal cord length and standard glottic area after 4 weeks in group C, D were significantly lower than those before surgery(t_{C left standard vocal cord length}=16.137, t_{C right standard vocal cord length}=13.984, t_{D left standard vocal cord length}=11.903, t_{D right standard vocal cord length}=14.587, t_{C standard glottic area}=10.280, t_{D standard glottic area}=22.974, P<0.05). During 6-18 months of follow-up in clinical patients, no one developed a glottic web. Three months after surgery, Jitter, Shimmer, noise to harmonic ratio(NHR), the maximum phonation time(MPT)in all patients were significantly different from preoperative(t_{intralaryngeal mucosal flap jitter}=24.885, t_{intralaryngeal mucosal flap shimmer}=22.643, t_{intralaryngeal mucosal flap NHR}=6.202, t_{intralaryngeal mucosal flap MPT}=-9.661, t_{free mucosal flap jitter}=25.459, t_{free mucosal flap shimmer}=18.683, t_{free mucosal flap NHR}=5.705, t_{free mucosal flap MPT}=-20.840, P<0.05). Conclusion: Mucosal flap combined with silicone keel is an effective technique for preventing and treating anterior commissure adhesion. The effect of pedicled intralaryngea lmucosal flap is better.