Morning-predominant Dysphagia in Myasthenia Gravis: A Report of Two Cases with Tongue Pressure Measurement

Introduction: Myasthenia gravis (MG) is an autoimmune disorder characterized by fatigable muscle weakness. While symptoms typically worsen from afternoon to evening, morning-predominant dysphagia has not been well characterized, and standardized methods to assess diurnal changes and fatigability in dysphagia have not been established. We report two cases of MG presenting with an atypical diurnal pattern of morning-predominant dysphagia, in which maximum tongue pressure (MTP) measurement was useful for objective assessment. Case Presentations: Case 1 was an 80-year-old woman without thymoma (anti-acetylcholine receptor [AChR] antibody 18.8 nmol/L, Myasthenia Gravis Foundation of America [MGFA] class IIIb, Myasthenia Gravis Activities of Daily Living [MG-ADL] score 10, percent vital capacity [%VC] 87.8%, Dysphagia Severity Scale [DSS] 3). Case 2 was a 75-year-old woman with thymoma (anti-AChR antibody 42.3 nmol/L, MGFA class IIIa, MG-ADL score 8, %VC 84.8%, DSS 7), who developed dysphagia after thymectomy (DSS 4). MTP demonstrated marked diurnal variation in both cases, with lower values in the morning compared with the afternoon (Case 1: 5.8 vs 14.9 kPa; Case 2: 8.5 vs 20.6 kPa). Early morning administration of acetylcholinesterase inhibitors and modification of breakfast texture effectively alleviated symptoms. With immunotherapy and swallowing rehabilitation, swallowing function improved in both cases (Case 1: DSS 6; Case 2: DSS 7). Conclusion: Morning-predominant dysphagia may represent an under-recognized pattern in MG. MTP provides a simple and objective method to quantify diurnal variation in swallowing function and may assist in optimizing medication timing and dietary management, potentially reducing the risk of aspiration and improving clinical outcomes.