Biomechanical model for muscular dysfunction of the human pharynx using finite element analysis

Objectives: The oropharynx functions to transport food from the oral cavity to the esophagus, as well as to maintain an air passage from the nose to the lungs. By combining data from prior material property experimentation, a 3-dimensional finite element method reconstruction of the pharynx, and the utilization of a optimization process based on an inverse dynamic approach, we can estimate the pressures and associated consecutive pressure gradients created internally when the pharynx functions during swallowing. Methods: In this study, pharyngeal muscular dysfunction was modeled under 3 scenarios of increasing tissue stiffness. This was done by modifications in the stress-strain relationship material property within the finite element method nodes. This mechanical property was used as a surrogate for clinical changes in muscle function complicating neuromuscular disorders, such as stroke and amyotrophic lateral sclerosis. The pharyngeal tissue and deformation of the cross-sectional area of the pharynx were analyzed while increasing the mechanical stiffness by 25%, 50%, and 75%. Results: Increases in stiffness resulted in modified pressure-area curves predicting diminished movement, primarily in stiffened regions. Conclusions: These simulation results may act as a clinical index illustrating the association between tissue dysfunction and pharyngeal pressure and movement dysfunction. This type of modeling has the potential to act as an investigational tool, as well as a predictive tool, regarding disease progression, cancer treatment, and perhaps even the effects of aging on swallowing function.