Functional significance of the ipsilateral hemisphere during movement of the affected hand after stroke

• Published in: Experimental neurology Vol. 190; no. 2; pp. 425 - 432
• Main Authors: Serrien, Deborah J., Strens, Lucy H.A., Cassidy, Michael J., Thompson, Alan J., Brown, Peter
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.12.2004; Elsevier
• Subjects: Adolescent; Adult; Aged; Biological and medical sciences; Blood. Blood coagulation. Reticuloendothelial system; Child; Coherence; EEG; Electroencephalography; Female; Functional coupling; Functional Laterality - physiology; Hand - physiology; Hand Strength - physiology; Humans; Male; Medical sciences; Middle Aged; Motor Cortex - physiopathology; Movement - physiology; Neurology; Neuronal Plasticity - physiology; Pharmacology. Drug treatments; Recovery of Function; Stroke - physiopathology; Vascular diseases and vascular malformations of the nervous system; Functional coupling; EEG; Coherence; Cerebral cortex; Motor pathway; Force; Central nervous system; Electrophysiology; Cardiovascular disease; Electroencephalography; Vascular disease; Electrodiagnosis; Improvement; Motor cortex; Coupling; Cerebrovascular disease; Human; Nervous system diseases; Stroke; Healthy subject; Nuclear magnetic resonance imaging; Hand; Cerebral disorder; Functional recovery; Central nervous system disease; Sensorimotor cortex; Medical imagery
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/j.expneurol.2004.08.004

Previous fMRI observations have suggested increased task-related activation of the ipsilateral cerebral motor cortex in patients recovering from stroke. This is generally taken to infer an increased output from this area, although the functional relevance of this has been questioned. Here, we use directed EEG coherence to reveal whether there is increased informational flow from the ipsilateral motor cortex following motor stroke, and through correlation with degree of recovery, establish that this pattern of activity is associated with limited functional improvement. Unrecovered (n = 14), recovered (n = 11) patients and healthy subjects (n = 16) performed an isometric grip task with either hand that corresponded to 25% of individual maximum force, while EEG was recorded. For unrecovered stroke patients, most task-related information flow between the sensorimotor cortices in the low beta band of the EEG came from the ipsilateral (undamaged) hemisphere during grip with the affected hand. This was not the case when they gripped with their unaffected hand, when cortical activity was driven from the contralateral sensorimotor cortex. The latter pattern was also seen in recovered patients and controls. These findings suggest a functional role for the ipsilateral hemisphere in organizing movement of the impaired limb following stroke, but only in those patients that do not make a good functional recovery. Patients making a fuller recovery organize movement-related cortical activity from the hemisphere contralateral to movement.