Intransitive limb gestures and apraxia following unilateral stroke

Apraxia is the loss of the ability to perform learned, skilled movements co rrectly, and is frequently attributed to left hemisphere damage (Heilman & Rothi, 1985). Recent work (Dumont, Ska, & Schiavetto, 1999) has shown a dis sociation between transitive (tool based; e.g., hammering a nail) and intra nsitive (expressive/communicative; e.g., waving goodbye) actions; however, few group studies have specifically addressed apraxia for intransitive gest ures. The present investigation examined the frequency and severity of prax is errors related to the production of intransitive gestures in left (LHD) or right hemisphere stroke (RHD) patients in the context of Roy's (1996) mo del of limb praxis. A total of 119 consecutive stroke patients (LHD=57, RHD =62) and 20 healthy age-matched controls performed eight intransitive gestu res to pantomime and imitation. Performance was quantified via a multi-dime nsional error notation system, providing detail about specific elements of performance (e.g., location), and a composite score reflecting overall gest ural accuracy. Analyses of pantomime and imitation performance revealed an equal percentage of apraxic patients in each stroke group, and the severity of apraxia in these groups was also equivalent. Further, analyses of the p atterns of apraxia specified by Roy (1996) revealed that patients in each s troke group demonstrated selective impairments in pantomime (LHD = 38%, RHD = 42%), or imitation (LHD = 9%, RHD = 5%) conditions, whereas others demon strated concurrent impairments (LHD = 30%, RHD = 22%)-indicating that strok e to either hemisphere can selectively impair each stage in the production of an intransitive action.