Evaluation of Dysphagia in Myositis and Muscular Dystrophy Using Real-Time MRI and Quantitative Muscle Ultrasound

Swallowing dysfunction-dysphagia-is a frequent and debilitating symptom in neuromuscular disorders, leading to malnutrition, cachexia, aspiration pneumonia, and death. Identification of the underlying pathophysiological mechanisms is important for diagnosis and treatment. As standard assessments have limitations, novel imaging techniques are needed. We here studied the utility of real-time MRI and quantitative muscle ultrasound for characterizing dysphagia in two different neuromuscular disorders.

This prospective cohort study included 18 patients with inclusion body myositis (IBM, 33% female, age 68.9 ± 7.7 years) and 13 with oculopharyngeal muscular dystrophy (OPMD, 62% female, age 55.9 ± 7.0 years) from two European Neuromuscular research centers (Nijmegen, NL; Göttingen, DE). Swallowing function was studied using real-time MRI (RT-MRI), FEES (flexible endoscopic evaluation of swallowing), and clinical assessments. T1-mapping and quantitative muscle ultrasound (QMUS) were used to analyse tissue properties in swallowing muscles. Outcomes were compared between the two muscle diseases. RT-MRI values were also compared with 22 age- and sex-matched non-myopathic controls.

RT-MRI revealed significantly prolonged oral transit times in OPMD vs. controls (difference between means = 581.2 ms, 95% CI 225.9-936.4, p = 0.002). Pharyngeal transit time was significantly prolonged in IBM vs. controls (difference between means = 1132.8 ms, 95% CI 482.2-1783, p = 0.001). A cricopharyngeal bar as a well-established morphological indicator of dysphagia was identified in 80% of patients with IBM compared with 53% in OPMD. Fatty degeneration of the tongue in OPMD significantly correlated between MRI-T1 values and ultrasound echogenicity (Spearman's ρ = -0.52, p = 0.005). ROC revealed excellent discrimination between diseases by combining RT-MRI, T1-mapping and QMUS (AUC = 0.95, 95% CI 0.86-1.00), while FEES and clinical assessments failed to differentiate specific patterns of dysphagia.

This study supports the value of novel MRI and ultrasound techniques for clinical use by identifying the pathophysiology and severity of impaired swallowing. Differentiating the phenotypes of dysphagia can aid in the diagnosis and treatment of affected patients. RT-MRI and QMUS may serve as outcome measures for swallowing in clinical trials.