Perspectives on neurorehabilitation of unilateral impairments through cross-education

Background: Cross-education is being increasingly investigated as an unconventional, exercise-based intervention to manage severely lateralized weakness. To date, however, cross-education seems more important to research than clinical practice. Aim: To provide foundation and context for an informed employment of cross-education in severely or predominantly unilateral weakness or motor impairment. Method: Qualitative, narrative commentary. Results: Based on the comprehensive overview on contralateral strength training approaches to hemiplegia and unilateral weakness in stroke survivors performed by Russell and colleagues as well as on our experiences in multiple sclerosis, there is a potential for cross-education as a useful training approach to hemiplegia and unilateral weakness in stroke survivors and multiple sclerosis patients and, overall, in neurorehabilitation. However, some limitations of this non-conventional approach have to be pointed out, such as the apparent lack of translation of the performance gains of the weaker untrained side into functional improvement, particularly for the lower limb. Conclusion: Cross-education may serve as a viable option for those patients presenting severe unilateral weakness who are not able to fully exercise their weaker side directly. However, it should not be recommended straightaway if the training goal is to improve outcomes other than strength. As such, contralateral training may prove as a primer to establish a minimum level of strength that may suffice to sustain direct training, which has been proved to prompt more meaningful functional changes. Implications for rehabilitation Cross-education consists of training the stronger limb to increase strength in the untrained weaker homologous muscles. This unconventional strategy is receiving increasing attention for possible applications in neurological populations exhibiting severe unilateral impairment. For those patients who are not able to fully exercise their weaker side it may represent a viable exercise option. However, cross-education should not be recommended straightaway if the training goal is to improve outcomes other than strength.