Effect of unilateral arytenoid lateralisation on the rima glottidis volume in cats: a cadaveric study

Abstract

Objectives: This study aimed to document the percentage increase in the rima glottidis volume after unilateral cricoarytenoid lateralisation (CAL) in feline cadavers and establish categories and ranges to evaluate the degree of arytenoid abduction. Methods: Left CAL was performed in nine cadavers. Pre- and postoperative video endoscopy was performed on each resting and lateralised larynx. The images were analysed using an imaging program. Based on reference markings, the increase in the volume of each rima glottidis was measured, and the penetration of the mucosa by the suture material was documented. Measurements were evaluated using Wilcoxon’s signed-rank test and objectively graded into four categories based on percentile volume increase, which were defined as unchanged (<103%), moderately lateralised (207%), sufficiently lateralised (311%) and over abducted (>312%). Results: During laryngoscopic examinations, none of the nine arytenoid cartilages was considered unchanged; one case was considered to be moderate, five were sufficiently lateralised and three were categorised as over abducted. Through objective videoendoscopic evaluations, we found that the mean increase in the rima glottidis volume was 264%. None of the larynxes were categorised as unchanged; two were categorised as moderately lateralised, with volume increases of 169% and 195%, respectively; four were categorised as sufficiently lateralised, with values in the range of 229–303%; and three were categorised as over abducted, with volume increases in the range of 324–335%. There was strong agreement between the objective and subjective evaluations. There was no evidence of mucosal perforation caused by the suture material. Conclusions and relevance: Unilateral CAL in cats is a feasible option for increasing the rima glottidis volume. Postoperative laryngoscopic values correlated well with objective measurements; therefore, it is a good method to assess the degree of arytenoid abduction. Moderate lateralisation results in a significant volume increase, but values above 324% cause deformation of the larynx.