[A comparison of the influence of certain contextual factors on the symptoms of persons with acquired verbal apraxia and verbal developmental apraxia].

Data on the individual symptoms of patients with acquired apraxia of speech and developmental apraxia of speech is of theoretical significance in the study of this disorder. A comparison of individual symptoms may shed light on error patterns in apraxia of speech, the possibility of types of apraxia of speech and on the nature of the disorder. In this study which was part of the wider investigation into the effect of variation in contextual factors on apraxia of speech (Van der Merwe, Uys, Loots and Grimbeek, 1987; 1988; Van der Merwe, Uys, Loots, Grimbeek and Jansen, 1989) the symptoms of four patients with acquired apraxia of speech and one subject with developmental apraxia of speech were compared. The auditorily perceived symptoms and the deviations in voice onset time, vowel duration and utterance duration of all the subjects were compared. The results indicated that the frequency of occurrence of certain symptoms created individual error patterns but also that all subjects had the high occurrence of symptoms which reflect the nature of the disorder in common. The subject with developmental apraxia of speech had all symptoms in common with the other subjects but exhibited less deviancy in the temporal flow of speech and in the duration of the utterance. He presented with more sound substitutions than did the acquired group. The theoretical implications of the results are discussed.