Understanding the nature of apraxia of speech: Theory, analysis, and treatment

Researchers have interpreted the behaviours of individuals with acquired ap raxia of speech (AOS) as impairment of linguistic phonological processing, motor control, or both. Acoustic, kinematic, and perceptual studies of spee ch in more recent years have led to significant advances in our understandi ng of the disorder and wide acceptance that it affects phonetic-motoric pla nning of speech. However, newly developed methods for studying nonspeech mo tor control are providing new insights, indicating that the motor control i mpairment of AOS extends beyond speech and is manifest in nonspeech movemen ts of the oral structures. We present the most recent developments in theor y and methods to examine and define the nature of AOS. Theories of the diso rder are then related to existing treatment approaches and the efficacy of these approaches is examined. Directions for development of new treatments are posited. It is proposed that treatment programmes driven by a principle d account of how the motor system learns to produce skilled actions will pr ovide the most efficient and effective framework for treating motor-based s peech disorders. In turn, well controlled and theoretically motivated studi es of treatment efficacy promise to stimulate further development of theore tical accounts and contribute to our understanding of AOS.