RESUMEN
OBJECTIVE: The aim of this study was to establish arytenoid asymmetry as a pre-operative predictive parameter for arytenoid adduction surgery in unilateral vocal fold paralysis and thereafter identify the most predictive parameter for arytenoid adduction among the established parameters. METHODS: A retrospective comparative study was undertaken. The 'arytenoid asymmetry angle' formed between skewed 'glottic' and 'interarytenoid' axes (traced along the plane of closure of the membranous and cartilaginous glottis, respectively) was quantified in pre-operative laryngoscopic images of 85 adults with unilateral vocal fold paralysis who underwent either type 1 thyroplasty (group 1) or type 1 thyroplasty with arytenoid adduction (group 2). The need for arytenoid adduction was determined intra-operatively based on subjective voice improvement and laryngoscopic results. RESULTS: Arytenoid asymmetry (p < 0.0001), posterior phonatory gap (p = 0.001) and vertical level difference (p = 0.004) were significantly greater in group 2 (descending order of parameters). Arytenoid asymmetry angle showed a significant positive correlation with the latter two parameters. CONCLUSION: Arytenoid asymmetry is the most predictive parameter for arytenoid adduction. An arytenoid asymmetry angle of more than or equal to 33.9° is an indication for arytenoid adduction. This aids in pre-operative planning of arytenoid adduction.