Patients with generalized myasthenia gravis (MG) may need more than symptom checklists to detect dangerous breathing problems, according to research published recently in the Journal of Neurology showing that commonly used self-reported scales can miss signs of respiratory weakness.
The results suggest that spirometry, a simple breathing test, remains critical for accurately assessing lung function and preventing life-threatening complications.
“Findings from this study emphasize that respiratory involvement in stable MG is relatively common,” the study’s authors said. “When respiratory impairment is suspected, spirometry remains essential for accurate assessment.”
In this cross-sectional study with a longitudinal subgroup, researchers evaluated 70 patients using the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale, the Myasthenia Gravis Composite (MGC) and the Quantitative Myasthenia Gravis (QMG) score, which includes spirometry. Although 100 patients completed testing, 30 were excluded due to missing respiratory data. A subgroup of 25 patients repeated testing after three years.
Read more about the prognosis of MG
The average participant was 59 years old and 59% were women, with overall disease severity considered mild to moderate. Based on self-reports, 57% of patients said their breathing was normal, 36% reported mild symptoms and 7% reported moderate symptoms. No one reported severe respiratory issues. Still, 30 patients, or 43%, described some level of breathing difficulty.
Objective testing told a more complex story. Lung function, measured by forced vital capacity, varied widely from 40% to 170% of predicted values. Some patients with significantly reduced lung capacity reported only mild symptoms, highlighting a disconnect between how patients feel and what tests show. The correlation between symptom scores and spirometry was weak, with borderline statistical significance.
Researchers also compared two groups: one defined by reported symptoms and another by reduced lung function. The overlap was only 48%, meaning many patients with measurable respiratory impairment were not identified through symptom reporting alone. Even when broader definitions were used, differences between groups remained limited.
Over time, patients in the follow-up subgroup showed improved lung function, while overall disease severity scores stayed mostly stable, though composite scores improved. These results suggest that respiratory status can change independently of general symptom burden.
For patients, these results indicate that feeling fine does not always mean breathing is normal. Even in stable outpatient settings, a substantial portion of individuals had reduced lung function. Regular spirometry can catch early changes that symptom scales might miss, allowing for earlier intervention and potentially preventing serious complications.
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