| Independent living essentially depends on the ability to manipulate objects in daily life. According to a simple mechanical representation of holding an object between the tips of the fingers and the thumb, the grip force (G) acts perpendicularly to the object's surface, while the load force (L) acts tangentially. An elaborate coordination between G and L provides G sufficient to prevent slippage, but not excessive to cause fatigue or crush the hand-held object. We investigated the specific aspects of hand function in mildly-to-moderately involved individuals with MS in static and dynamic manipulation tasks using an instrumented device and compared them with healthy individuals. The hand function was assessed through kinetic variables, such as the indices of task performance (i.e., the ability to exert the prescribed L profile) and force coordination (i.e., G/L ratio, G-L coupling, and G modulation). In addition to unimanual ones, we also evaluated complex bimanual manipulation tasks, as well as the tasks that were performed with and without visual feedback. The results of the dissertation generally suggest that the applied methodology could be sensitive enough in detecting functional impairments of hand function even in mildly involved individuals with MS across a wide range of manipulation tasks. Given a general lack of objective, quantitative tests of hand function in the clinical setups, these findings strongly advocate the development of the applied methodology into a standard clinical test for the assessment of hand function in a variety of neurological diseases, including MS. |
