Ballard et al. | 2016

— Purpose —

“The purpose of this study was to assess predictor variables for the presence of AOS after left-hemisphere stroke, with the goal of increasing diagnostic objectivity and efficiency.”

— Findings —

72 participants were given a variety of testing batteries (WAB-R, ABA-2, PALPA, ASSIDS, Lexical stress testing, jaw visuomotor tracking tasks, and OME) and were judged by experts on presence/absence of AOS, Dysarthria, Oral Apraxia, and Phonological Paraphasias through a survey form. From the results in the testing batteries, the authors used computational/statistical methods to reveal variables that were predictive of the experts diagnostic choices.

Two variables were demonstrated to predict the experts choices with 93% accuracy:
1. Errors on Word of Increasing Length (E_WIL)*
2. Pairwise Variability Index for Weak-Strong words (PVI_WS)^

The data shows that high E_WIL scores and low PVI_WS scores are associated with presence of AOS.

Scores of [ E_WIL > 0.017 ] and { PVI_WS < 112“ } yielded 85.71% sensitivity and 91.89% specificity.

For more info on scoring, guidelines, and diagnostic determination review paper + supplementary materials from authors.

*taken from Apraxia Batter for Adults-2 Subtest: Words of Increasing Length
^acoustic results taken from speech analysis on Praat
“PVI_WS = 112 is more lenient, PVI_WS = 100 is more stringent

— Citation —

Ballard, K. J., Azizi, L., Duffy, J. R., McNeil, M. R., Halaki, M., O’Dwyer, N., Layfield, C., Scholl, D. I., Vogel, A. P., & Robin, D. A. (2016). A predictive model for diagnosing stroke-related apraxia of speech. Neuropsychologia, 81, 129–139