Swallowing impairment (dysphagia) is a common sequela in patients with motor neuron disease (MND). The purpose of this retrospective, observational pilot investigation was to characterize how pharyngeal swallowing mechanics are impacted in patients with MND using a comparison with healthy, non-dysphagic control group. Computational analysis of swallowing mechanics (CASM) was used to determine covariate biomechanics of pharyngeal swallowing from videofluoroscopic assessment in 15 patients with MND and 15 age- and sex-matched healthy controls. Canonical variant analysis with post hoc discriminate function analysis (DFA) was performed on coordinate data mapping functional muscle groups underlying pharyngeal swallowing. Differences in swallowing mechanics associated with group (MND; control), motor neuron predominance (upper; lower), onset (bulbar; spinal), and swallow task (thin, pudding) were evaluated and visualized. Pharyngeal swallowing mechanics differed significantly in patients with MND compared with healthy controls (D = 2.01, p < 0.0001). Post hoc DFA pairwise comparisons suggest differences in pharyngeal swallow mechanics by motor neuron predominance (D = 5.03, p < 0.0001), onset (D = 2.03, p < 0.0001), and swallow task (D = 1.04, p < 0.0001). Pharyngeal swallowing mechanics of patients with MND differ from and are more heterogeneous than healthy controls. These findings suggest patients with MND may compensate reductions in pharyngeal shortening and tongue base retraction by extending the head and neck and increasing hyolaryngeal excursion. This work and further CASM investigations will lead to further insights into development and evaluation of targeted clinical treatments designed to prolong safe and efficient swallowing function in patients with MND.
Motor neuron disease Deglutition Deglutition disorders Morphometric Modified barium swallow study Healthy
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This study was partially supported by the following grant mechanisms: Veterans Affairs, RR&D 1IK1RX001628-01A1 (PI: Garand); National Institutes of Health, NCATS TL1R000061 (PI: Brady: Project PI: (Focht) Garand; National Institutes of Health, NIDCD 1K24DC12801 (PI: Martin-Harris); and American Speech-Language-Hearing Foundation (Recipient: Garand). Further, this study was partially supported by the J. Harold Harrison M.D. Scholars Program and MCG Medical Scholars Program at Augusta University.
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Conflicts of interest
The authors declare that they have no conflict of interest.
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