Study designs of evaluations included in the review
Randomised controlled trials (RCTs), case-control studies and case series were eligible for inclusion.
Specific interventions included in the review
Studies investigating noninvasive ES (using surface electrodes) provoking muscle contraction, applied to the affected upper extremity, were eligible for inclusion. The included studies used triggered stimulation (electromyogram stimulation and positional feedback stimulation training) and non-triggered stimulation (neuromuscular ES stimulation, transcutaneous electrical nerve stimulation and electroacupuncture). Most of the included studies used a fixed frequency ranging from 20 to 50Hz, and a variety of different muscles were stimulated. The frequency of treatment ranged from 30 minutes once daily to 1 hour, three times per day and the duration ranged from 2 weeks to 3 months. Where comparators were used, they varied and included no therapy, sham stimulation, and voluntary movements and extensions.
Participants included in the review
Studies of people who had experienced a stroke were eligible for inclusion. The participants in the included studies had varying degrees of stroke severity. Some had experienced a stroke in the previous month (acute), in the previous 1 to 6 months (sub-acute), or over 6 months previous (chronic). Some of the studies were exclusively of patients with residual wrist extension of at least 5 to 20 degrees; some studies did not report inclusion criteria, while others used a variety of inclusion criteria.
Outcomes assessed in the review
Studies reporting relevant outcome measures for motor control of the upper extremity were eligible for inclusion. Further details were not specified. Individual included studies used several outcome measures. The selected primary outcome measures were isometric strength wrist extensors, sustained contraction of wrist or finger extensor muscles, strength wrist extensors, Fugl Meyer Motor Assessment, Rivermead, Motor Assessment, isometric strength finger extension, Motoricity Index and grip strength. To reduce bias, grip strength and wrist extensor strength were also assessed.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.