posted on 2015-02-01, 00:00authored byElizabeth Murray, Patricia McCabe, Robert Heard, Kirrie J. Ballard
Purpose The gold standard for diagnosing childhood apraxia of speech (CAS) is expert judgment of perceptual features. The aim of this study was to identify a set of objective measures that differentiate CAS from other speech disorders.
Method Seventy-two children (4–12 years of age) diagnosed with suspected CAS by community speech-language pathologists were screened. Forty-seven participants underwent diagnostic assessment including presence or absence of perceptual CAS features. Twenty-eight children met two sets of diagnostic criteria for CAS (American Speech-Language-Hearing Association, 2007b; Shriberg, Potter, & Strand, 2009); another 4 met the CAS criteria with comorbidity. Fifteen were categorized as non-CAS with phonological impairment, submucous cleft, or dysarthria. Following this, 24 different measures from the diagnostic assessment were rated by blinded raters. Multivariate discriminant function analysis was used to identify the combination of measures that best predicted expert diagnoses. Results The discriminant function analysis model, including syllable segregation, lexical stress matches, percentage phonemes correct from a polysyllabic picture-naming task, and articulatory accuracy on repetition of /pətəkə/, reached 91% diagnostic accuracy against expert diagnosis.
Conclusions Polysyllabic production accuracy and an oral motor examination that includes diadochokinesis may be sufficient to reliably identify CAS and rule out structural abnormality or dysarthria. Testing with a larger unselected sample is required.
This research was supported by the Douglas and Lola Douglas Scholarship on Child and Adolescent Health, the Nadia Verrall Memorial Research Grant (2010), a Postgraduate Research Award (2011) from Speech Pathology Australia, and the James Kentley Memorial Scholarship and Postgraduate Research Support Schemes to Elizabeth Murray; a University of Sydney International Program Development Fund Grant to Patricia McCabe and Kirrie Ballard; and an Australian Research Council Future Fellowship (FT120100255) to Kirrie Ballard. Parts of this article were presented at the Motor Speech Conference in Santa Rosa, CA, 2012, and the Speech Pathology Australia Conference in Hobart, Tasmania, 2012. We thank research assistants Morin Beausoleil, Virginia Caravez, Claire Formby, Jennifer Fortin Zornow, Sally Hanna, Claire Layfield, Aimee-Kate Parkes, Gemma Patterson, Alyssa Piper, and Caitlin Winkelman. Thank you also to Samantha Warhurst, Kate Anderson, and Claire Layfield for editorial suggestions.