TREATMENT FOR APRAXIA OF SPEECH

Treatment for Apraxia of Speech

Abstract

The purpose of the present paper is to present a critical review and reanalysis of response generalization effects in studies of treatment efficacy in apraxia of speech (AOS). Response generalization takes two forms: generalization of treatment effects to untrained exemplars of trained behaviors and generalization to untrained (i.e., novel) behaviors. In the past, response generalization has not been extensive and typically has been restricted to untrained exemplars of trained behaviors. Reasons for these findings are discussed with reference to recent advances in our understanding of the nature of AOS and to theories of speech motor control and learning. The discussion focuses on the influence of the theoretical basis used to develop hypotheses and select behaviors to test predictions, the complexity of the treatment task/s, and patient characteristics. Suggestions for future directions in treatment efficacy research are offered. Learner outcomes: (1) An understanding of the nature of AOS, based on recent experimental analyses. (2) An understanding of the efficacy of current treatments for AOS in the area of response generalization. (3) An understanding of how theories of speech motor control might be applied to develop hypotheses for testing and increase effectiveness in treatment studies. (4) An understanding of how theories of speech motor control might guide selection of behaviors to test treatment effects and response generalization.

Treatment for Apraxia of Speech

Introduction

Apraxia of speech (AOS) is a potentially devastating disorder that renders a person unable to use verbal communication effectively. Several treatment approaches have been developed to remediate this motor programming impairment (see Wambaugh & Doyle, 1994 for a review) but their success in terms of response generalization has been limited. Most treatment approaches have been motivated by the surface symptoms of AOS (Darley and Kent) rather than by a theory of normal speech motor control or of its breakdown. In recent years, researchers have provided more objective descriptions of AOS and several theories of the underlying disorder. Furthermore, theories of normal speech motor control have become more sophisticated and more specified. As would be expected, treatment research is lagging behind. The present paper draws together reports on response generalization and reevaluates them in light of recent advances. A new perspective for facilitating response generalization is suggested.

In the field of speech and language pathology, AOS is typically referred to as a phonetic-motoric disorder rather than a linguistically based disorder (see Ballard; Code and McNeil for reviews). McNeil et al. (1997) defined AOS as a disorder affecting the translation of an intact phonological representation of a message into the learned kinematic parameters for an intended movement. Code (1998) presented a slightly different perspective stating that AOS is a motoric disorder that manifests itself at both phonetic and phonological levels.

Methods

A relatively consistent observation in studies of treatment efficacy is that acquisition, maintenance, and generalization results vary across individuals. This is assumed to result from heterogeneity in patient characteristics such as extent and profile of impairment. Wertz et al. (1984) noted that being greater than 1 month post-onset ...