Making the invisible audible: a real-world connected speech study in myasthenia gravis

Background: Bulbar involvement in myasthenia gravis (MG) can affect voice and speech; however, task-dependent and potentially subclinical alterations are often underrecognized. Methods: We conducted a cross-sectional study of consecutively enrolled adults with confirmed MG at a single center. Participants completed standardized voice recordings and contemporaneous clinical assessments [Myasthenia Gravis–Activities of Daily Living (MG-ADL) and revised Myasthenia Gravis Quality of Life (rMG-QOL15)]. Tasks included sustained vowels, standardized reading, and spontaneous speech. Acoustic metrics comprised root-mean-square intensity (RMS, dB) and fundamental frequency (F0, Hz). Results: Seventeen patients were enrolled (median age 58 years; 52.9% female). Median MG-ADL was 6.0 and mean rMG-QOL15 was 16.6, with no significant correlation (ρ = 0.09, p = 0.74). Male participants exhibited significant intensity reductions in connected speech: reading (−3.22 dB, IQR − 5.98 to −2.09; pBH = 0.031; r = 0.84) and spontaneous speech (−5.46 dB, IQR − 6.11 to −4.93; pBH = 0.031; r = 0.84). Female participants showed smaller, non-significant changes (≤ − 2.2 dB; all pBH > 0.7). F0 shifts were modest and non-significant after correction. Across the cohort, MG-ADL correlated with both RMS and F0 drops in unadjusted models but not after adjusting for sex. rMG-QOL15 showed no overall association, although females demonstrated a correlation between F0 drop and QOL burden (ρ = 0.77, p = 0.014). Conclusion: Connected-speech intensity decrements may represent a sensitive acoustic marker of load-dependent and potentially subclinical bulbar dysfunction in MG, not fully captured by patient-reported outcomes, with potential sex-related differences requiring further validation in larger cohorts.