Anatomical Study of the Larynx With Implications for Medialization Thyroplasty.

Objetives: Montgomery medialization thyroplasty involves fitting a silicone prosthesis in the thyroid cartilage according to gender-based placement criteria. This standardized procedure can lead in some cases to suboptimal results. The aim of this study is to identify individual anatomical differences between same-gender patients that could explain the occasional failures.

Methods: A prospective anatomical study was performed using 28 human laryngeal specimens (14 male, 14 female) obtained by clinical necropsy. Different measures on the thyroid ala were taken in order to describe the morphology of the thyroid cartilage and the location of the vocal fold: the distance between the superior thyroid notch and the inferior thyroid border (A), the distance between inferior thyroid border and inferior tubercle of the thyroid cartilage (B), the projection of the vocal fold into the thyroid ala including the distance between the anterior commissure and the inferior border of the thyroid cartilage (D1), and the distance between the projection of the vocal process of the arytenoid and the laryngeal tubercle (D2). Statistical analysis was performed to determine the relationship between gender and the mentioned measurements. A P value of 0.05 was considered statistically significant.

Results: High rates of interindividual anatomical variability were observed irrespective of gender. In male samples, measurements A, B, D1, and D2 varied up to 5, 10, 8, and 8 mm respectively. Variability was even more evident in female larynges which varied up to 11, 7, 8, and 9 mm, respectively. The results of the measurements were similar between male and female.

Conclusion: Montgomery thyroplasty failures can be due to individual anatomical variations regardless of gender. Based on our results, there is a significant interindividual anatomical variability irrespective of gender, even more evident among women. Customizing the location of the prosthesis may be an efficient way to solve this difficulty.