Syllable use in apraxia of speech: Preliminary findings

Abstract

Background: Apraxia of speech (AOS) is an acquired sensorimotor disorder characterised by an impairment in the ability to program purposeful movements for speech in the absence of muscle weakness or paralysis. Due to motor programming difficulties, individuals with AOS make more errors as the complexity of a phoneme, syllable, word, or phrase increases. They also tend to produce short words and exhibit "syllabic speech", the production of syllables lacking prosody with intersyllabic pauses. While the syllable is a fundamental unit of speech in AOS, little is known about the syllable shapes used by individuals with AOS in discourse. Aims: The aim of this study was to determine if individuals with AOS produce shorter words with simpler syllable structure in spontaneous speech compared to neurologically normal individuals. Methods & Procedures: Five speakers with AOS and Broca's aphasia and five gender- and age-matched neurologically normal individuals participated in the study. One hundred conversational turns related to a topic chosen by the participant and conversational partner were transcribed and analysed to determine the frequency of occurrence of (1) monosyllabic, disyllabic, and polysyllabic words, (2) syllable shapes (V, CV, VC, CVC, complex), and (3) syllabic alterations. The frequency of content and function words was also analysed for 50 conversational turns for both groups. Outcomes & Results: The mean number of syllables per word was significantly greater for the normal group than for the group with AOS (p < .05). Compared to the normal participants, the participants with AOS used a significantly higher proportion of V and CV forms (p < .05) and a significantly lower proportion of CVC and complex syllables (p < .05). Participants with AOS used the same percentage of content words for all syllable shapes except for CVC words, where they used a significantly lower percentage than the normal group (p < .05). Conclusions: Individuals with AOS use shorter words than neurologically normal individuals. Among monosyllabic words, they use more simple (open) syllable shapes and fewer complex (closed) syllable shapes in spontaneous speech. Except for CVC words, they use the same percentage of content words as neurologically normal individuals in order to convey meaning.