Reduced tongue force and functional swallowing changes in a rat model of post stroke dysphagia

Purpose: Dysphagia is a common problem after stroke that is often associated with tongue weakness. However, the physiological mechanisms of post-stroke tongue muscle weakness and optimal treatments have not been established. To advance understanding of physiological mechanisms of post stroke dysphagia, we sought to validate the unilateral transient middle cerebral artery occlusion (MCAO) rat model of ischemic stroke as a translational model of post stroke dysphagia. Our goal was to establish clinically relevant measures and chronicity of functional deficits; criteria that increase the likelihood that findings will translate to the clinic. We hypothesized that MCAO would cause tongue weakness and functional swallowing changes. Methods: Maximum voluntary tongue forces and videofluoroscopic swallowing studies were collected in 8-week old male Sprague-Dawley rats prior to receiving either a left MCAO (N = 10) or sham (N = 10) surgery. Tongue forces and VFSS were reassessed at 1 and 8 weeks post-surgery. Results: Maximum voluntary tongue force, bolus area, and bolus speed were significantly reduced in the MCAO group at the 1 and 8-week timepoints. Conclusion: Clinically relevant changes to swallowing and tongue force support the use of the MCAO rat model as a translational model of post stroke dysphagia. This model will allow for future studies to improve our understanding of the physiology contributing to these functional changes as well as the impact of therapeutic interventions on physiological targets and function.