Effect of contralateral finger touch on grip force control in individuals with multiple sclerosis

Abstract

It was recently shown that the magnitude of grip force utilized to lift and transport a hand-held object decreased if a light touch from the contralateral finger is provided [Aruin AS. Support-specific modulation of grip force in individuals with hemiparesis. Arch Phys Med Rehabil 2005;86:768-75]. The rationale of the study is to find out whether or not the individuals with multiple sclerosis (MS) have the same behavior as control subjects. Eight patients with MS and eight control subjects performed the task of lifting and transporting an instrumented object with provision of light touch of the contralateral index finger to the wrist of the target arm and without it. The tasks of placing the object on a shelf and a simulation of a drinking maneuver were studied. Peak grip force, force ratio, latency, and time lag were recorded and analyzed. The mean peak grip force decreased in conditions with application of light finger touch in patients and control subjects while performing both the experimental tasks. The force ratio also improved with application of light finger touch. Individuals with MS apply smaller grip force if they utilize a finger touch. Findings provide better understanding of how patients with MS control grip force and suggest that a light touch approach could be considered as a valuable modality in the rehabilitation of these patients.