Manual asymmetries in tool-use: implications for apraxia.

Previous examinations of manual performance asymmetries have utilised relatively simple movements such as goal-directed aiming and rapid finger-tapping. In the present research, three-dimensional kinematic analyses were employed to examine manual asymmetries in the production of transitive limb gestures. Transitive limb gestures involve the use of tools and/or objects and are complex movements used in the evaluation of limb apraxia. Ten healthy right hand dominant participants produced two transitive limb gestures in response to verbal command both with (tool-use) and without (pantomime) the appropriate tool. Analyses revealed a dominant (right) hand advantage, although the magnitude of this advantage was influenced by movement context (pantomime vs tool-use). This study provides the first evidence that manual asymmetries are elicited during the production of transitive limb gestures, and mandates that future kinematic analyses of limb apraxia consider the impact of pre-morbid manual asymmetries when contrasting the performance of left and right hemisphere damaged patients.