PRAXIS PERFORMANCE WITH LEFT VERSUS RIGHT-HEMISPHERE LESIONS

Praxis is defined as skilled, purposive limb movement. While it has be en a consistent finding that lesions of the left cerebral hemisphere r esult in significantly worse performance on praxis testing than lesion s of the right cerebral hemisphere, recently some investigators have p roposed that the right hemisphere may also play an important role in m ediating praxis. To learn if the right hemisphere does have a role in praxis we studied right-handed patients with right or left hemisphere lesions, as well as right-handed normal controls who were matched for age and education. Two trained raters scored the transitive gesture pe rformance of the forelimb ipsilateral to the injured hemisphere. For t he normal controls, left and right hand performances were scored separ ately and used for statistical comparison. Independent comparisons wer e made on six dimensions that are important for accurate gesture perfo rmance and on an overall apraxia score. When compared to normal contro l subjects the patients with left hemisphere lesions (LHD) did demonst rate deficient praxis; that is, ideomotor apraxia. However, those with right hemisphere lesions (RHD) did not. Based on this study it would appear that the right hemisphere does not play a crucial role in praxi s. (C) 1997 Elsevier Science Ireland Ltd.