Physikalische und histologische untersuchungen an normalen und einem weiblichen virillsierten kehlkopf

An Integrated Experimental-Computational Study of Vocal Fold Vibration in Type I Thyroplasty

Subject-specific computational modeling of vocal fold (VF) vibration was integrated with an ex vivo animal experiment of type 1 thyroplasty to study the effect of the implant on the vocal fold vibration. In the experiment, a rabbit larynx was used to simulate type 1 thyroplasty, where one side of the vocal fold was medialized with a trans-muscular suture while the other side was medialized with a silastic implant. Vocal fold vibration was then achieved by flowing air through the larynx and was filmed with a high-speed camera. The three-dimensional computational model was built upon the pre-operative scan of the laryngeal anatomy. This subject-specific model was used to simulate the vocal fold medialization and then the fluid-structure interaction (FSI) of the vocal fold. Model validation was done by comparing the vocal fold displacement with postoperative scan (for medialization), and by comparing the vibratory characteristics with the high-speed images (for vibration). These comparisons showed the computational model successfully captured the effect of the implant and thus has the potential for presurgical planning.

Stress-strain response of the human vocal ligament

The longitudinal elastic properties of the human vocal ligament were quantified by stress-strain measurements and by modeling the response mathematically. Human ligaments were obtained from surgery and autopsy cases. They were dissected, mounted, and stretched with a dual-servo ergometer to measure force versus elongation and to convert the results into stress and strain. To calculate a longitudinal Young's modulus, the stress-strain curves were fitted with polynomial and exponential functions and differentiated. Young's modulus was separately defined in the low- and high-strain regions. The mean Young's modulus for the low-strain region was 33.1 +/- 10.4 kilopascals. In the high-strain region, A and B parameters for an exponential fit were 1.4 +/- 1.0 and 9.6 +/- 1.2 kilopascals, respectively. The stress-strain and Young's modulus curves showed the typical hysteresis and nonlinearity seen previously in other vocal fold tissues (muscle and mucosa), but the nonlinearity was most profound for the vocal ligament.