Associations and dissociations of transitive and intransitive gestures in left and right hemisphere stroke patients.

The study investigated performance on pantomime and imitation of transitive and intransitive gestures in 80 stroke patients, 42 with left (LHD) and 38 with right (RHD) hemisphere damage. Patients were also categorized in two groups based on the time that has elapsed between their stroke and the apraxia assessment: acute-subacute (n=42) and chronic (n=38). In addition, patterns of performance in apraxia were examined. We expected that acute-subacute patients would be more impaired than chronic patients and that LHD patients would be more impaired than RHD patients, relative to controls. The hemisphere prediction was confirmed, replicating previous findings. The frequency of apraxia was also higher in all LHD time post-stroke groups. The most common impairment after LHD was impairment in both pantomime and imitation in both transitive and intransitive gestures. Selective deficits in imitation were more frequent after RHD for transitive gestures but for intransitive gestures they were more frequent after LHD. Patients were more impaired on imitation than pantomime, relative to controls. In addition, after looking at both gesture types concurrently, we have described cases of patients who suffered deficits in pantomime of intransitive gestures with preserved performance on transitive gestures. Such cases show that the right hemisphere may be in some cases critical for the successful pantomime of intransitive gestures and the neural networks subserving them may be distinct. Chronic patients were also less impaired than acute-subacute patients, even though the difference did not reach significance. A longitudinal study is needed to examine the recovery patterns in both LHD and RHD patients.