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Abstract
Diadochokinesis (DDK) for speakers with dysarthria has been described using a variety of acoustic measures. A clinical protocol for the objective assessment of DDK requires a unified approach, however, to facilitate implementation across clinics and laboratories. A protocol for the acoustic analysis of DDK that incorporates temporal and energy measures has been used to describe DDK characteristics for dysarthria secondary to stroke as well as ataxic dysarthria. The current study sought to validate and extend the protocol to a new set of etiological groups, including dysarthria secondary to multiple sclerosis (MS) and Parkinson's disease (PD). The results suggest that temporal measures are more useful than energy measures for distinguishing among dysarthria secondary to MS, dysarthria secondary to PD, and healthy controls. The results also highlight the value of including both alternating and sequential motion rate tasks in the assessment of DDK and of supplementing quantitative measures with qualitative spectrographic observations.
Copyright (C) 2003 S. Karger AG, Basel
Key Words
Diadochokinesis * Multiple sclerosis * Parkinson's disease
not well represent movement strategies for connected speech [4, 5]. Nonetheless, maximally rapid syllable repetition or DDK is thought to be useful for the differential diagnosis of dysarthria and presumably neurologic disease, as well as for determining the severity of speech motor control impairments [1, 2]. The following paragraphs highlight the range of acoustic measures that have been used to quantify DDK in dysarthria, with a focus on spastic, ataxic, and hypokinetic dysarthria.
In addition to global and segmental timing measures such as syllable repetition rate and stop gap duration, the temporal regularity of DDK has been quantified in dysarthria. Increased temporal variability or irregularity of DDK is thought to be most characteristic of ataxic dysarthria [13-15]. However, increased temporal variability also has been reported for speakers with spastic and hypokinetic dysarthria, relative to healthy controls [6, 9, 13, 16].
Energy characteristics for DDK tasks also have been described for some dysarthrias, but have been examined less thoroughly than temporal characteristics of DDK. Spirantization or high-frequency noise energy during stop gap intervals in DDK tasks has been noted for hypokinetic dysarthria secondary to Parkinson's disease (PD) as well as spastic dysarthria [e.g., 6, 8, 9]. Reduced vocal intensity reported for some speakers with dysarthria secondary to PD...