Differential Diagnosis between Apraxia and Dysarthria Based on Acoustic Analysis

Article excerpt

Acoustic analysis provides objective quantitative measures of speech that enable a comprehensive and accurate understanding of motor disorders and complement the traditional measures. This paper aims to distinguish between normal and pathological speech, more specifically between apraxia of speech and spastic dysarthria in native Spanish speaking patients using acoustic parameters. Participants (4 aphasic with apraxia of speech, 4 with spastic dysarthria, and 15 without speech disorders) performed three different tasks: repeating the syllable sequence [pa-ta-ka], repeating the isolated syllable [pa] and repeating the vowel sequence [i-u]. The results showed that the normative values of motor control, in general, coincide with those obtained in previous research on native English speakers. They also show that damage to motor control processes results in a decrease in the rate of alternating and sequential movements and an increase in the inter-syllabic time for both types of movements. A subset of the acoustic parameters analyzed, those that measure motor planning processes, enable differentiation between normal population and apraxic and dysarthric patients, and between the latter. The differences between the pathological groups support the distinction between motor planning and motor programming as described by van der Merwe's model of sensorimotor processing (1997).

Keywords: acoustic, apraxia, dysarthria, motor control.

El análisis acústico proporciona medidas cuantitativas objetivas del habla que permiten una comprensión global y más exacta de sus trastornos motores complementando a las medidas tradicionales. En el presente trabajo se realiza un estudio diferencial entre normalidad motora del habla y habla patológica y, dentro de ésta, entre apraxia del habla y disartria espástica basado en parámetros acústicos en pacientes hablantes nativos de español. Los participantes (4 afásicos con apraxia del habla, 4 con disartria espástica y 15 sin patología) realizaron tres tareas: repetir la secuencia silábica [pa-ta-ka], repetir la sílaba aislada [pa] y repetir la secuencia vocálica [i-u]. Los resultados mostraron que los valores normativos de control motor coinciden en general con los obtenidos en investigaciones con hablantes nativos de inglés y que la afectación de los procesos de control motor da lugar a un decremento de la tasa de movimientos alternantes y de movimientos secuenciales así como a un incremento de los tiempos intersilábicos para ambos tipos de movimientos. Un subconjunto de los parámetros acústicos analizados, aquellos que reflejan los procesos de planificación motora, permite diferenciar entre la norma y los pacientes apráxicos y disártricos, y a su vez entre estos. Las diferencias encontradas entre ambos grupos patológicos apoyan la distinción entre planificación motora y programación motora descrita en el modelo de procesamiento sensoriomotor de van der Merwe (1997).

Palabras clave: acústica, apraxia, control motor, disartria.

All those alterations resulting from lesions to the peripheral or central nervous system affecting speech motor control processes are included under the heading of motor speech disorders. Two major categories can be distinguished within the motor speech disorders: apraxia of speech and dysarthria (Duffy, 1995; Roig-Quillis & Rodriguez-Palmero, 2008; Gamboa, Jiménez-Jiménez, Mate, & Cobeta, 2001).

To understand and differentiate these two conditions, and given that verbal production is a complex process, it is necessary to use a multidimensional explanation that will provide complementary points of view. Specifically, the emphasis in the explanation and characterization of these conditions can be made on verbal, cognitive or neuroanatomical elements. Each point of view allows for a partial analysis that, when integrated with the others, provides a comprehensive understanding of the pathology. This also enables a more robust differential diagnosis. …