Evaluation of an asymmetric anterior glottic web in an excised canine larynx model

Abstract

The main objective of the study is to model asymmetry within anterior glottic webs in excised larynges using sutures and apply aerodynamic and acoustic analyses. Anterior glottic webs (AGW) were modeled in eight excised larynges using sutures secured at the level of the glottis to mimic the scar tissue of the web. Each of the eight larynges were tested under three different pressure increments for each of the three models of AGW: symmetric, vertically asymmetric, and laterally asymmetric. Phonation threshold pressure (PTP) and flow (PTF) differed significantly across AGW conditions (p = 0.006 and p = 0.005, respectively). Additionally, vocal efficiency was significantly different among conditions (p = 0.005) as well as significantly lower in the asymmetric groups (p = 0.015 and p = 0.007). Perturbation measures were not significantly different across conditions. Correlation dimension (D2) was significantly different at PTP, 1.25 × PTP, and 1.5 × PTP (p = 0.003, p = 0.010, and p < 0.001, respectively) as well as significantly higher in the asymmetric groups at each pressure increment. The increased PTP, PTF, and D2 values as well as decreased vocal efficiency among the asymmetric conditions indicates a significant decrease in vocal function, and thus represents that asymmetries could be a contributing factor to the pathological symptoms associated with glottic webs.

Development of Excised Larynx

“…They determined that the symmetry vs. asymmetry of the web had no effect on either parameter. 14 Mills et al used excised rabbit larynges to show a decreasing trend in SPL at the phonation instability threshold as vocal folds were manually elongated. 3 SNR was also successfully measured in excised rabbit larynges by Maytag et al, but no other significant conclusions were made.…”

“…This supports that an asymmetric laryngeal glottic web will decrease the voice quality. 14 When there is damage to the vocal folds, many clinicians try to promote epithelial recovery or repair defects. Cobden et al applied platelet-rich plasma on wounded rat vocal folds and used the excised larynx set-up to evaluate vascular endothelial growth factor, fibroblast growth factor receptor, and epithelial growth factor receptor (EGFR) immunohistochemical staining.…”