Myasthenia gravis primarily affects skeletal muscles, yet non-motor manifestations, particularly urinary incontinence (UI) and overactive bladder (OAB) symptoms, remain underexplored in MG. Given the impact of UI on quality of life, systematic investigation in MG is clinically important.

Eighty-six MG patients and 90 age- and sex-matched inpatient controls were evaluated in a cross-sectional, case-control study. All participants completed the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-UI SF) and the Overactive Bladder Symptom Score (OABSS). MG severity was assessed using the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale. MG patients were further categorized into early-onset (EOMG), late-onset (LOMG), and very late-onset (VLOMG) subgroups. Logistic regression identified predictors of UI, and Kaplan-Meier analysis was used to evaluate time to first recalled UI symptoms.

MG patients had over four times higher prevalence of UI symptoms (ICIQ-UI SF ≥6 in 52.3% vs. 12.2% in controls; p<0.001). LOMG patients exhibited the highest UI prevalence (63.2%) and progressed most rapidly to UI, while EOMG patients had the latest onset. OAB symptoms were also more prominent in MG, marked by higher OABSS (p<0.001), increased nocturia (≥3/night: 27.9% vs 11.1%; p=0.004), and greater urgency episodes (≥2/day: 38.4% vs 2.2%; p<0.001). MG-ADL score independently predicted UI (OR 2.38; 95% CI 1.04–5.46; p=0.041).

UI and OAB symptoms are more common in MG patients than in controls. Disease severity, as assessed by MG-ADL, is an independent predictor of UI, and age at disease onset may influence the timing of UI development. Routine screening and proactive management of UI in MG are warranted to improve patient quality of life and functional outcomes.