Internally and Externally Paced Finger Movements Differ in Reorganization After Acute Ischemic Stroke

Abstract

Askim T, Indredavik B, Håberg A. Internally and externally paced finger movements differ in reorganization after acute ischemic stroke. Objective To identify adaptive changes within the motor network for internally and externally paced finger movements in the acute and chronic phase after ischemic stroke. Design A functional magnetic resonance imaging study of internally and externally paced thumb–index-finger opposition 4 to 7 days and 3 months after stroke and in healthy controls. Images were compared within and between groups, with the actual number of movements as regressors. Setting Stroke Unit, University Hospital. Participants Twelve patients with mild to moderate acute ischemic stroke and 15 controls (N=27). Intervention Stroke unit treatment focused on very early rehabilitation, followed by early supported discharge service. Main Outcome Measure Differences in brain activation between patients and controls and between the tasks. Results Patients showed significant improvement in hand function at follow-up. Brain activity related to internally paced finger movements normalized with time. For the externally paced, accurate timing task, brain activity in the chronic phase differed from that seen in the controls despite successful recovery of hand function. In comparing the externally and internally paced tasks, a trend toward recruiting a premotor-parietal-striatal network was found in patients in the chronic phase, whereas controls had increased activation of a sensorimotor network consisting of primary motor cortex, supplementary motor cortex, superior parietal lobe, thalamus, and cerebellum. Conclusions After ischemic stroke, brain activity subserving an internally paced motor task normalized with time, whereas motor activity in response to an externally paced task became dependent on a premotor network. These findings underscore the importance of task-specific training in the rehabilitation of stroke patients. In the future, physiotherapists should evaluate the possibility of enhancing the recovery of a more efficient network for externally paced tasks.