Useful Landmarks in Arytenoid Adduction and Laryngeal Reinnervation Surgery

Investigation of the Position and Angle of the Vocal Fold Projected onto the Thyroid Cartilage

OBJECTIVE

To perform laryngeal framework surgery for unilateral vocal fold paralysis and obtain favorable voice improvement, it is necessary to accurately determine the vocal fold and arytenoid cartilage positions. Thus, the position and angle of the paralyzed vocal folds and arytenoid cartilage projected onto the affected thyroid plate were measured using computed tomography (CT) before and after surgery.

METHODS

Forty-six male patients with thyroid cartilage ossification observed on preoperative CT and vocal fold paralysis were included. Using Adobe Illustrator®, the thyroid plate on the affected side was reconstructed from the continuous images of the sagittal section of the CT examination during participant's quiet breathing (reconstructed affected thyroid plate [RATP]).

RESULTS

The anterior commissure mean position was slightly cranial to the midpoint of the thyroid cartilage midline. The paralyzed vocal fold angle was not parallel to the baseline. The average unaffected vocal fold angle during vocalization projected onto the affected thyroid plate was 13.83°, which differed significantly from the average paralyzed vocal fold angle before surgery (19.05°). However, no significant difference was observed in comparison with the average angle of the paralyzed vocal fold after arytenoid adduction. The average distance from the inferior notch of the affected side thyroid cartilage to the affected arytenoid cartilage was 16.7 mm.

CONCLUSION

By understanding the positional relationship between the thyroid cartilage plate and internal structure from preoperative CT images, more effective surgery can be performed according to individual differences.

LEVEL OF EVIDENCE

IV Laryngoscope, 2024.

Laryngeal Framework Surgical Anatomy: A Radiological Study

PURPOSE

Awareness of variations in laryngeal anatomy among different age and gender groups is crucial during laryngeal framework surgery. The aim of this study is to demonstrate the relationship between gender and laryngeal radiologic morphometrics among different age groups and the applicability of important anatomical landmarks of laryngeal surgery.

METHODS

Laryngeal images of 180 adult patients older than 18 years of age were obtained by computed tomography and assessed. A total of 11 measurements of important laryngeal landmarks were taken from the patients' computed tomography images. Results were subgrouped according to gender and age, and these groups were compared for each measurement.

RESULTS

The majority of laryngeal measurements obtained in the study were higher in males than females, with the exception of the interlaminar angle. The mean interlaminar angle value was 88.27°± 14.99 for males and 103.04°± 14.81 for females (P <0.005). The distance from the anterior commissure to the inferior border of the thyroid cartilage was 10.46 ± 2.5 mm for males and 7.72 ± 1.9 mm for females. The anterior commissure locates slightly higher than the midpoint of the distance from the thyroid notch to the thyroid inferior border. The shortest distance between the muscular process of the arytenoid cartilage and the thyroid cartilage was found to be 9.60 ± 3.47 mm for males and 7.72 ± 2.33 mm for females (P <0.001).

CONCLUSION

Observation of obvious diversities in the size and distance of the important laryngeal structures between the gender groups is an important factor to be considered for successful laryngeal framework surgery. Also, using the midpoint of the thyroid cartilage as a landmark for anterior commissure is a practical method during surgery, especially for thyroplasty.

Oblique thyroarytenoid muscle in humans: An independent muscle or an accessory belly?

OBJECTIVES/HYPOTHESIS

This study aimed to determine the prevalence and morphological variations of the oblique thyroarytenoid (TA) muscle in humans.

STUDY DESIGN

Cadaveric anatomic dissections.

METHODS

One hundred hemilarynges from 50 formalin-embalmed cadavers were dissected to investigate the morphology of muscle fibers of the TA muscle.

RESULTS

Thirty-six (36%) hemilarynges were found to have a distinct oblique belly superficial to the TA muscle. In 28 cases, the belly had a relatively constant origin and an insertion that extended straight onto the TA muscle from the anterosuperior area of the internal surface of the thyroid lamina to the base of the muscular process of the arytenoid cartilage. Eight cases were located in a similar area but with some differences in the origin or insertion features.

CONCLUSIONS

We proposed that the oblique TA muscle has a high prevalence and probably acts to close and relax the vocal cords. It remains to be determined whether the oblique TA muscle is an independent muscle or an accessory belly of the main TA muscle.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:1634-1638, 2018.

Framework Surgery for Treatment of Unilateral Vocal Fold Paralysis

Laryngeal framework surgery is the current gold standard treatment for unilateral vocal fold paralysis. It provides a permanent solution to glottic insufficiency caused by injury to the recurrent laryngeal nerve. Various modifications to the original Isshiki type I laryngoplasty procedure have been described to improve voice and swallowing outcomes. The success of this procedure is highly dependent on the experience of the surgeon as it epitomizes the intersection of art and science in the field. The following article reviews the evidence, controversies, and complications related to laryngoplasty for unilateral vocal fold paralysis. It also provides a detailed analysis of how and when arytenoid-positioning procedures should be considered, and summarizes the literature on postoperative outcomes.

Localization of the muscular process for arytenoid adduction surgery

OBJECTIVES/HYPOTHESIS

Arytenoid adduction (AA) surgery can be technically challenging, potentially limiting its utilization in general practice. Because AA often serves as an adjunct to thyroplasty type I (TTI) in the management of unilateral vocal fold paralysis, this study sought to define the anatomic position of the muscular process (MP) of the arytenoid cartilage in relation to the TTI window and other key thyroid cartilage landmarks, thereby facilitating a more efficient surgical approach.

STUDY DESIGN

Cadaveric anatomic dissections.

METHODS

Arytenoid MPs were identified bilaterally in eight cadavers for a total of 16 hemilarynges. The location of the MP was measured relative to the anteroinferior corner of the traditional TTI window and also relative to the roots of the superior and inferior cornua for comparison with other studies.

RESULTS

: The muscular processes were located along an axial line extending posteriorly from the inferior border of the TTI window and parallel to the inferior border of the thyroid cartilage. In males, the mean distance to the MP was 26.9 mm from the anteroinferior corner of the window, whereas in females the mean distance was 18.9 mm. In all cases, the MP was inferior to the midpoint between the roots of the superior and inferior cornua (mean inferior offset = 2.7 mm).

CONCLUSIONS

The TTI window can be used intraoperatively to help locate the arytenoid muscular process during arytenoid adduction surgery.