Task demands and limb apraxia in stroke

The present study was designed to examine the frequency and severity of apr axia in patients with left- or right-hemisphere stroke in both pantomime an d imitation conditions and to compare the frequency of apraxia in each stro ke group across the three patterns of apraxia described in Roy's model (Roy , 1996). Ninety-nine stroke patients and 15 age-matched healthy adults perf ormed eight transitive gestures to pantomime and to imitation. Gestural per formance was quantified as accuracy on five performance dimensions; a compo site score, an arithmetic combination of the five performance dimensions, w as used as an index of the overall accuracy. Analyses revealed a comparable proportion of patients in each stroke group were classified as apraxic in the imitation condition, but a higher proportion of left stroke patients we re apraxic in the pantomime condition. The severity of apraxia in each stro ke group and the performance dimensions affected were, however, comparable. Analyses of the patterns of apraxia (pantomime alone, imitation alone or a praxia in both conditions) revealed a higher frequency of apraxia in both s troke groups for the pattern reflecting apraxia in both conditions, indicat ing that a disruption at the movement execution stage of gesture performanc e was most common. (C) 2000 Academic Press.