Apraxia of Speech in Acute Post-Stroke Patients: Exploring the Pairwise Variability Index in French and Estimating Prevalence

This study examined whether the word-level Pairwise Variability Index (PVI) distinguishes apraxia of speech (AOS) from other post-stroke speech and language disorders in French, and estimated the prevalence of AOS in the acute phase of left-hemispheric stroke. 93 participants took part in the study including 47 left-hemispheric stroke patients: patients with AOS (n = 7), patients without AOS (n = 41), and control participants (CTRL) (n = 45). Participants read 40 bisyllabic French words selected to maximise vowel-duration contrasts. Vowel durations were extracted using an automatic alignment tool and manually verified. A linear mixed-effects model assessed group differences in word-level PVI while adjusting for demographic and linguistic covariates. Prevalence estimates were based on a clinical cohort of 52 patients. The model showed significant effects of Group and Age. Participants with AOS produced lower word-level PVI values than both CTRL and non-AOS patients. Age was positively associated with PVI. The estimated prevalence of AOS among patients with acute left-hemispheric stroke was 15%. The findings indicate that the word-level PVI captures reduced durational contrast in French-speaking patients with post-stroke AOS. These results support research on the PVI as a complementary acoustic measure in early post-stroke assessment.