Lower limb Fitts' task motor performance in patients with and without imaging evidence of unilateral lumbar nerve root compression


Shelley Sargent1, Steven Passmore1,2 1College of Rehabilitation Sciences, University of Manitoba 2 Faculty of Kinesiology & Recreation Management, University of Manitoba The present experiment sought to determine if diagnostic imaging findings of nerve root compression could predict lower limb Fitts' task performance. Patients presenting with back, and or leg pain to a surgical screening spine assessment clinic (N=45) were recruited and stratified into 3 groups based on clinical presentation: 1) positive imaging, positive neurological deficit; 2) positive imaging, negative neurological deficit; and 3) negative imaging, negative neurological deficit. Each group performed great toe pointing movements to squares projected on a platform with 4 possible indices of difficulty (ID). An NDI 3D Investigator (300Hz) recorded all movement in the sagittal plane. Movement time (MT), reaction time (RT), peak velocity (PV), peak acceleration (PA), time to peak velocity (ttPV) and time to peak acceleration (ttPA) were analyzed using 3 Group (1,2,3) by 4 ID (3,4a,4b,5) ANOVA models. Performance variables were also compared to traditional questionnaire-based clinical outcome measures. Main effects for ID were found for MT, PV, PA, ttPV and ttPA. No group, or group by ID interactions were found. Pearson's Correlation analysis revealed significant associations between self-report measures and motor performance variables for Group 2. Positive correlations were found for effected limb MT and the Oswestry Disability; effected limb MT and the Roland Morris Disability Questionnaire; and non-effected limb ttPA and non-effected limb Quadruple Numeric Pain Rating Scale (QNRS). A negative correlation was found for effected limb RT and the effected limb QNRS. Findings are discussed related to Fitts' Law interpretation, and clinical implications for performance-based outcome measure application.