A New Diagnostic Tool for Apraxia in Patients with Right-Hemisphere Stroke: The Revised Cologne Apraxia Screening (KAS-R)

The Cologne Apraxia Screening (KAS) was developed to diagnose apraxia following left-hemisphere (LH) stroke. The present study aims at developing a diagnostic tool for patients with right-hemisphere (RH) stroke (KAS-R) by modifying the test material of the KAS and reducing the test items based on psychometric analyses. A total of 100 patients with RH stroke and 77 healthy control participants were tested. Psychometric analyses led to the exclusion of 8 KAS items. The final KAS-R, consisting of 12 items, shows good internal consistency (alpha=0.795) as well as high sensitivity (79.4%) and specificity (84.4%). Applying a cut-off value of <= 46 (out of 48) points, 39 RH stroke patients were diagnosed with apraxia. Significant correlations were found between the KAS-R and an imitation test as well as expert ratings, indicating high construct validity. The results suggest that the KAS-R is a reliable and valid diagnostic tool for apraxic deficits after RH stroke.