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JSLHR

Toward a Quantitative Basis for Assessment and Diagnosis of Apraxia of Speech
Katarina L. Haley,a Adam Jacks,a Michael de Riesthal,b Rima Abou-Khalil,b and Heidi L. Rotha

Purpose: We explored the reliability and validity of 2 quantitative approaches to document presence and severity of speech properties associated with apraxia of speech (AOS). Method: A motor speech evaluation wasadministered to 39 individuals with aphasia. Audio-recordings of the evaluation were presented to 3 experienced clinicians to determine AOS diagnosis and to rate severity of 11 speech dimensions. Additionally, research assistants coded 11 operationalized metrics of articulation, fluency, and prosody in the same speech samples and in recordings from 20 neurologically healthy participants. Results:Agreement among the 3 clinicians was limited for both AOS diagnosis and perceptual scaling, but inter-observer reliability for the operationalized metrics was strong. The relationships between most operationalized metrics and mean severity ratings

for corresponding perceptual dimensions were moderately strong and statistically significant. Both perceptual scaling and operationalizedquantification approaches were sensitive to the presence or absence of AOS. Conclusions: Perceptual scaling and operationalized metrics are promising quantification techniques that can help establish diagnostic transparency for AOS. However, because satisfactory reliability cannot be assumed for scaling techniques, effective training and calibration procedures should be implemented. Operationalized metricsshow strong potential for enhancing diagnostic objectivity and sensitivity. Key Words: perceptual evaluation, acoustic analysis, differential diagnosis, motor speech disorders, aphasia

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ore than 4 decades have passed since Darley (1968) called for clinical differentiation of apraxia of speech (AOS) from other neurologic disorders affecting speech production. Today, the diagnostic entity iswidely accepted on the basis of its conceptual differentiation from the dysarthrias and aphasia; yet, the process for making the diagnosis is not well established. In the clinical setting, it is most important to differentiate AOS from aphasia with phonemic paraphasia (e.g., Wernicke’s and conduction aphasia) and unilateral upper motor neuron (UUMN) dysarthria, which can have similar features to AOSand can also be caused by

left cerebral injury. In addition, differentiation from spastic dysarthria and hypokinetic dysarthria is important in cases with bilateral or basal ganglia involvement. The location of structural neurological lesions within the left hemisphere has, so far, offered limited value with regard to differential diagnosis, in large part because the same neural substrate isshared by varied speech functions and because stroke and other applicable etiologies usually affect large cortical and subcortical areas. Although it is recognized that AOS, dysarthria, and aphasia commonly coexist, this complication is rarely explored in clinical research, and its manifestation is, consequently, poorly understood. The diagnosis of AOS is based on the interpretation of perceptualobservations that are made on a collection of speech properties considered characteristic of the disorder (Darley, 1968; McNeil, Robin, & Schmidt, 2009; Wertz, LaPointe, & Rosenbek, 1984). The diagnostic approach is typically impressionistic and pattern-based, in which an experienced clinician integrates multidimensional observations with his or her knowledge and previous experience to determinewhether an individual has the disorder. The assumption is that the combination of experience and reliance on accepted diagnostic criteria

The University of North Carolina at Chapel Hill Vanderbilt Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee Correspondence to Katarina L. Haley: Katarina_Haley@med.unc.edu Editor: Anne Smith Associate Editor: Wolfram...