Title: Computational analysis of swallowing mechanics in patients with ALS
Additional authors (in order): Amy Chen, MD, PhD, Ryan Schwertner, and William G. Pearson, Jr., PhD.
Institution name, city, state, country of additional authors: Medical University of South Carolina, Charleston, SC, USA (AC); and Augusta University, Augusta, GA, USA (RS and WP)
Background: Swallowing impairment (dysphagia) is a common sequela in patients with amyotrophic lateral sclerosis (PALS). The most commonly used instrumental method to assess oropharyngeal swallowing function is the modified barium swallow study (MBSS) – a videofluoroscopic diagnostic procedure using real-time x-ray imaging. Computational analysis swallowing mechanics involves mapping and collecting coordinates of anatomical landmarks to track and analyze the covariant biomechanics of swallowing observed on MBSSs. Purpose: The aim of this retrospective study was to determine how swallowing mechanics are affected in PALS. Methods: A semi-automated Matlab tracker tool was used to track ten anatomical landmarks in MBS videos of 15 PALS and 15 age- and sex-matched (healthy) controls. MorphoJ software was used to provide statistical analysis and visualization of changes in coordinate position indicating swallowing mechanics. Results: Canonical variant analysis naming group (PALS/control) and swallowing domain (oral/pharyngeal) as independent variables showed 40% of the variation in swallowing mechanics was due to the disease state. In PALS, eigenvectors indicated an increase in hyolaryngeal elevation and head and neck extension, while there was a decrease in tongue base retraction and pharyngeal shortening Discriminant function analysis of lower motor neuron (LMN) predominance compared to upper motor neuron (UMN) predominance in PALS demonstrated increased excursion of the hyoid, pharynx, and head and neck extension in LMN compared to UMN patients. Discussion/Conclusions: These preliminary results could indicate a response compensating for hypotonicity of muscles in those with LMN predominance. Ongoing work includes longitudinal analyses of the change of swallowing mechanics in PALS as disease progresses, as well as associations with other clinical variables of interest including pulmonary function and ratings of disease severity. This work may provide insights into the development of targeted clinical treatment designed to prolong safe and efficient swallowing function in PALS.
