Bilateral Synergy: A Framework for Post-Stroke Rehabilitation

Background: Unilateral stroke produces debilitating deficits in voluntary control in the contralesional arm, and significant motor coordination deficits in the ipsilesional arm. In addition, patients tend to avoid bilateral arm patterns and during performance of activities of daily living. Nevertheless, upper extremity physical rehabilitation predominantly focuses on motor training activities with only the paretic arm. This can be limiting because of persistent deficits in the ipsilesional arm, and because of the tendency of patients to avoid spontaneous bilateral arm patterns.

Proposition: Rehabilitation should focus on bilateral training to advance recovery of function in both arms of stroke patients, as well as to facilitate spontaneous bilateral arm use. This paper reviews the rationale for this approach, citing evidence for significant hemisphere specific bilateral motor deficits in stroke patients, which affect both the contralesional and the ipsilesional arm. The rationale for, and advantages of, training both arms simultaneously through bilateral tasks is reviewed. Although bilateral training has been employed to treat stroke patients previously, this has tended to focus on bimanual 'coupling' as a rationale for performing parallel, but not cooperative bilateral tasks. Bilateral synergy provides a more functional framework for structuring post-stroke upper extremity rehabilitation.

Conclusion: Bilateral synergy may be causally linked to spontaneous bilateral arm use, suggesting that rehabilitation should be focused on bilateral cooperative tasks, such as bilateral object transport. Further research is required to determine whether this approach could be efficacious for patients with hemiparesis, and whether both left and right hemisphere strokes can benefit from such intervention.