Chapter 12 Motoric Characteristics of Adult Aphasic and Apraxic Speakers

Abstract

Aphasia, apraxia of speech and dysarthria are the three major impairments of spoken language resulting from damage to the nervous system. Traditional definitions of these disorders imply clear separations in terms of the affected mechanisms or processes. For example, aphasia is assumed to be an impairment of language rather than a disorder of the motor control of speech. However, the contemporary classification of aphasia rests to a large degree on characteristics of speech, perhaps even on characteristics of speech motor control. This chapter examines evidence of motor disturbances in the speech patterns of certain aphasia ‘types’ and in apraxia of speech. Data from perceptual, acoustic, and physiologic investigations point strongly to the conclusion that movement-level disturbances can be observed in apraxia of speech, Broca aphasia, conduction aphasia and Wernicke aphasia. It is concluded that traditional classifications and descriptions of the aphasia syndromes and of apraxia of speech should be reconsidered in the light of recent perceptually, acoustically and physiologically derived evidence for speech movement-level deficits in speakers with these disorders.