Error Variability and the Differentiation Between Apraxia of Speech and Aphasia With Phonemic Paraphasia PurposeThis study was conducted to evaluate the clinical utility of error variability for differentiating between apraxia of speech (AOS) and aphasia with phonemic paraphasia.MethodParticipants were 32 individuals with aphasia after left cerebral injury. Diagnostic groups were formed on the basis of operationalized measures of recognized articulatory and prosodic characteristics of ... Article
Article  |   June 01, 2013
Error Variability and the Differentiation Between Apraxia of Speech and Aphasia With Phonemic Paraphasia
 
Author Affiliations & Notes
  • Katarina L. Haley
    University of North Carolina at Chapel Hill
  • Adam Jacks
    University of North Carolina at Chapel Hill
  • Kevin T. Cunningham
    University of North Carolina at Chapel Hill
  • Correspondence to Katarina L. Haley: Katarina_Haley@med.unc.edu
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Julie Liss
    Associate Editor: Julie Liss×
Article Information
Speech, Voice & Prosodic Disorders / Apraxia of Speech & Childhood Apraxia of Speech / Language Disorders / Aphasia / Speech, Voice & Prosody / Speech
Article   |   June 01, 2013
Error Variability and the Differentiation Between Apraxia of Speech and Aphasia With Phonemic Paraphasia
Journal of Speech, Language, and Hearing Research, June 2013, Vol. 56, 891-905. doi:10.1044/1092-4388(2012/12-0161)
History: Received May 21, 2012 , Accepted October 28, 2012
 
Journal of Speech, Language, and Hearing Research, June 2013, Vol. 56, 891-905. doi:10.1044/1092-4388(2012/12-0161)
History: Received May 21, 2012; Accepted October 28, 2012
Web of Science® Times Cited: 10

PurposeThis study was conducted to evaluate the clinical utility of error variability for differentiating between apraxia of speech (AOS) and aphasia with phonemic paraphasia.

MethodParticipants were 32 individuals with aphasia after left cerebral injury. Diagnostic groups were formed on the basis of operationalized measures of recognized articulatory and prosodic characteristics of AOS and phonemic paraphasia. Sequential repetitions of multisyllabic words were elicited as part of a motor speech evaluation and transcribed phonetically. Four metrics of variability at the syllable and word levels were derived from these transcripts.

ResultsThe measures yielded different magnitudes of variability. There were no group differences between participants who displayed speech profiles consistent with AOS and participants who displayed speech profiles indicative of aphasia with phonemic paraphasia. Rather, correlation coefficients and analyses of covariance showed that the variability metrics were significantly mediated by overall error rate. Additionally, variability scores for individuals with salient diagnoses of AOS and conduction aphasia were inconsistent with current diagnostic guidelines.

ConclusionsThe results do not support diagnostic validity of error variability for differentiating between AOS and aphasia with phonemic paraphasia. Future research using error variability metrics should account for overall error rate in the analysis and matching of participant groups.

Acknowledgments
This work was supported by Grants R03DC006163 and R43DC009708 from the National Institute on Deafness and Other Communication Disorders and by a grant from the University of North Carolina Research Council. We thank Erika Rogawski for her assistance with data collection.
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