Bimanual interaction as an illustration of an integrative approach in post-stroke neurorehabilitation

The review addresses the roles of interhemispheric asymmetry and interhemispheric interaction in the pathogenesis and medical rehabilitation after stroke, with a focus on bimanual training to restore upper-extremity motor function. After a stroke, 50-80% of patients persist with movement disorders affecting not only the paretic but also the «healthy» ipsilateral limb, leading to the avoidance of bilateral patterns in daily activities. Interhemispheric asymmetry is a fundamental property of the brain that is disrupted during a stroke, leading to an imbalance with increased excitability in the intact hemisphere and suppression of the affected hemisphere's functions, which aggravates motor and cognitive deficits after a stroke. Interhemispheric interaction, mainly through the corpus callosum, provides coordination of the brain hemispheres; however, in stroke it leads to an abnormal imbalance, reducing plasticity. Methods for restoring interhemispheric communication include noninvasive brain stimulation (transcranial magnetic stimulation and transcranial direct current stimulation), brain-computer interfaces, and physical activity modulating cerebral hemispheric connectivity. Particular attention is paid to bimanual motor training, which stimulates neuroplasticity, improves bimanual coordination, and reduces the severity of interhemispheric asymmetry. Neuromotorics, a set of bimanual exercises for training fine motor skills, is described. These approaches, especially when combined, are effective for motor recovery but depend on the stroke period and individual factors. The practical significance of integrative rehabilitation in overcoming interhemispheric imbalance and improving patients' functionality and quality of life is emphasized. Further research is needed to optimize bimanual therapy.