Évaluation des dysarthries et des apraxies de la parole : quelles approches ?

Context. In clinical practice, acquired motor speech disorders (MSDs), dysarthria and/or apraxia of speech (AoS) are mainly assessed using a perceptual approach. This approach remains dominant despite the biases associated with phonemic restoration and the subjectivity of the listener's internal representations. Furthermore, there is a lack of international consensus on the main diagnostic criteria for AoS. Several of these features are shared with dysarthria, which also often coexists with AoS (Duffy, 2019). In this context, the assessment of MSDs for differential diagnosis is a major challenge. Aims. This article provides an overview of the studies resulting from our PhD thesis. The aim of the thesis was to examine the contribution of the perceptual, acoustic and cognitive approaches to the assessment of dysarthria and AoS for the diagnosis and characterisation of these MSDs. Methods. Three studies were conducted on 4 groups of speakers: neurotypical, pathological speakers with AoS, hypokinetic dysarthria in Parkinson's disease, and mixed flaccid-spastic dysarthria in amyotrophic lateral sclerosis. These studies, partly based on the MonPaGe-2.0.s corpus (Fougeron et al., 2018 ; Laganaro et al., 2021 ; Pernon et al., 2020), focused on each of the following assessment approaches: (i) a multi-judge auditory-perceptual classification task of MSDs, (ii) a discrete phonetic-acoustic analysis by speech dimension of the speakers with the lowest and highest accuracy rates in (i), (iii) a dual-task paradigm evaluating the effects of attentional and executive demands on speech and non-verbal tasks in neurotypical speakers. Results. There was little difference between the perceptual and acoustic assessment approaches in diagnosing MSDs. The perceptual approach failed to diagnose very mild MSDs. The acoustic approach provided a quantified characterisation of MSDs profiles on average across three speech dimensions assessed by the MonPaGe-2.0.s tool, as in the study of perceptual classification of MSDs. The bidirectional dual-task effects showed that the mode of presentation of the stimuli and their modality, the type of speech task and the attentional demand of the non-verbal tasks had to be taken into account when developing and interpreting dual-task performance. These three studies found differences depending on the speech task. Conclusion. In addition to considering the speech dimensions involved in speech tasks, a more precise examination of their cognitive-motor demands on speech (type of speech task, phonetic and linguistic complexity of the corpus, speech production condition) refines the differential diagnosis of MSDs and improves their characterisation during assessment.