Changes in Sensorimotor Performance After Stroke and as a Function of Normal Aging

Abstract

Stroke is a leading cause of disability in Canada. To maximize a patient's chance of returning to their pre-stroke state, rehabilitation programs must be tailored to their specific brain impairments. Unfortunately, assessment of post-stroke impairments is largely based on the perceptual decisions of a clinician. To ensure inter-rater reliability, many current assessment tools use coarse, ordinal scales resulting in floor and ceiling effects. The purpose of this thesis was to use robotic technology coupled with a visually guided reaching task to develop a reliable and sensitive tool for assessing upper limb motor function after stroke. Robotic devices have contributed greatly to our under- standing of motor function because of their ability to objectively, repeatedly, and reliably measure behavior. Visually guided reaching is an ideal task for assessing up- per limb motor function because it requires a broad range of sensorimotor functions as well as healthy functioning of a diverse neural network. Control and stroke subjects performed an unassisted visually guided reaching task with each arm using the KINARM robot. Sensorimotor functions were assessed using a broad range of parameters derived from the kinematics of movement. In our first study we examined the reaching performance of subjects with subacute stroke and reliably found impairments in both their affected and unaffected arms. We also found performance asymmetries between the affected and unaffected arms that were present even when both arms demonstrated normal reaching behaviour independently. In our second study we examined changes in reaching performance that occur over the first six months following stroke. We found that with time reaching performance improved with both arms, but performance asymmetries persisted throughout the first six months after stroke. In our final study we examined reaching performance of healthy adults between the ages of 20 and 84 years of age. We found linear declines with age across most of our movement parameters, but interlimb asymmetries to be stable across adulthood. To generate age-specific performance curves descriptive statistics were tabulated for each parameter. The results of this thesis demonstrate that a visually guided reaching task can provide reliable and sensitive information about a subject's sensorimotor impairments following stroke.