TNM glottic: role of the vocal muscle, arytenoid cartilage, and inferior paraglottic space in impaired vocal cord mobility (T2). An embryological and clinical study.

The TNM classification is unsatisfactory regarding the impaired mobility of the vocal cord and/or the arytenoid. The authors have studied the intrinsic laryngeal musculature, with particular attention to the medial thyroarytenoid muscle, the lateral thyroarytenoid muscle, and the inferior paraglottic space. The study was conducted on serial sections of 4 embryonal and 9 fetal larynges at different stages of development. The embryological observations showed that the lateral and medial thyroarytenoid muscles have different maturation times and probably different functions: phonatory and sphincteric. The authors have found that the inferior paraglottic space is situated between these 2 muscles. It would represent a path of diffusion for glottic cancer and play a central role in impaired vocal cord and/or arytenoid mobility, according to the degree of diffusion. Embryological observations have suggested the existence of laryngeal morphofunctional units belonging to the subsites of the glottic region and related to tumoral spreading.