Unilateral Strength Training of the Less Affected Hand Improves Cortical Excitability and Clinical Outcomes in Patients With Subacute Stroke: A Randomized Controlled Trial

Abstract

Objectives: To investigate whether unilateral strength training helps improve cortical excitability and clinical outcomes after stroke.

Design: Randomized controlled trial.

Setting: Rehabilitation sciences research center.

Participants: Patients with subacute stroke (N=26) were randomly assigned to a control group (n=13) or the experimental group (n=13).

Interventions: Participants in both groups received conventional physiotherapy. The experimental group also received unilateral strength training of the less affected wrist extensors. Interventions were applied for 4 weeks (12 sessions, 3 d/wk).

Main outcome measures: Cortical excitability in both the ipsilesional hemisphere (ipsiH) and contralesional hemisphere (contraH) was assessed by measuring resting motor threshold (RMT), active motor threshold (AMT), motor evoked potential (MEP), and cortical silent period (CSP) at baseline and after the 4-week intervention period. Clinical outcomes were obtained by evaluating wrist extension strength in both the more affected and less affected hands, upper extremity motor function, activities of daily living (ADL), and spasticity.

Results: The experimental group showed greater MEP amplitude (P=.001) in the ipsiH and shorter CSP duration in both the ipsiH (P=.042) and contraH (P=.038) compared with the control group. However, the reductions in RMT and AMT in both hemispheres were not significantly different between groups. Improvements in wrist extension strength in the more affected (P=.029) and less affected (P=.001) hand, upper extremity motor function (P=.04), and spasticity (P=.014) were greater in the experimental group. No significant difference in ADLs was detected between groups.

Conclusions: A combination of unilateral strength training and conventional physiotherapy appears to be a beneficial therapeutic modality for improving cortical excitability and some clinical outcomes in patients with stroke.

Keywords: Cortical excitability; Rehabilitation; Stroke; Upper extremity.