Quantitative Assessment Method of Force Tracking Capabilities for Detection of Motor Intentional Disorders

Abstract

Early detection of motor intentional disorders associated with dysfunction in the action-intention system of the brain is clinically important to provide timely intervention. This study developed a force tracking system that can record forces exerted by the index finger while tracking 5 N, 10 N, 15 N, and 20 N of target forces varying over time. The force tracking system quantified force control measures (initiation time IT; development time, DT, maintenance error, ME; termination time, TT; tracking error, TE) for the individual and overall force control phases. This study evaluated the effectiveness of the force tracking system for a normal control group (n = 12) and two patient groups diagnosed with subcortical vascular mild cognitive impairment (svMCI, n = 11) and subcortical vascular dementia (SVaD, n = 13). Patients with SVaD showed significantly worse force control capabilities in IT (0.84 s) and ME (1.71 N) than those with svMCI (0.64 s in IT, and 1.38 N in ME). Patients with svMCI had significantly worse capabilities in IT, ME, and TE (3.80 N) than the control group (0.49 s in IT, 0.78 N in ME, and 3.07 N in TE). The prevalence rates of force control capabilities lower than the 99% confidence interval of the control group ranged from 17% to 62% for the two patient groups. The force tracking system can sensitively quantify the severity of the force control deficiencies caused by dysfunction in the action-intention system of the brain.