1. Biomechanics of the Recurrent Laryngeal Nerve in Piglets
Megan Alexander
University of Arizona
NASA Arizona Space Grant Symposium
Tempe, AZ April 18, 2009
Jonathan Vande Geest, PhD (University Arizona)
Department of Aerospace and Mechanical Engineering
GIDP Biomedical Engineering
Bio5 Institute for Collaborative Bioresearch
Soft Tissue Biomechanics Laboratory (STBL)
Julie Barkmeier-Kraemer, PhD (University Arizona)
Department of Speech, Language and Hearing Sciences

2. Agenda
Introduction
Purpose
Methods
Results
Conclusions/Applications

3. Introduction UVP-Unilateral Vocal Fold Paralysis
Causes voice and swallowing problems such as the inability to speak
Occurs by damage to the recurrent laryngeal nerve (RLN), possibly due to surgery, tumor, or post-surgical inflammation
15-20% of cases are idiopathic (of unknown cause)

4. Purpose
Study the role of the RLN connective tissues in the idiopathic onset of UVP by investigating the biomechanical properties along the length and in between the left and right RLN.

5. Perkin Elmer Dynamic Mechanical Analyzer available in the STBL
Methods
Seven piglet left and right RLNs were stretched uniaxially in 37°C PBS at 5%/min up to 25%
An isotropic, hyperelastic constitutive model was used to model each nerve segments behavior during uniaxial extension. W is the strain energy density, T11 represents Cauchy Stress, λ 11 is stretch, and α and β are the model parameters. . . . ]
)][ 3 2 ( 4 [ 1 11 - + = l b a T
Perkin Elmer Dynamic Mechanical Analyzer available in the STBL

6. Nonlinear Regression  , ]
)][ 3 2 ( 4 [ 1 11 - + = l b a T
Nonlinear Regression  , 
Tyield
MTM
yield

7. Results – Differences Left to Right
Results showed higher MTM values in the right RLN segment than for the left.

8. Results – Differences Along Length of Nerve
MTM values increased in the regions near the aortic arch segments (segments 2 and 3).
Yield stress also displayed a similar trend for Segments 2 and 3

9. Conclusion
Left and right RLNs differ in their ability to withstand stretch
Segments of the left RLN near the aortic arch may be more resistant to stretch
This research offers insight regarding the protective function of the RLN connective tissues and structural compromise due to its environment. Identifying RLN structure-function relationships may be important in understanding nerve damage associated with vocal fold paralysis.

10. Thank You
Questions?