Therapeutic electrical stimulation to improve motor control and functional abilities of the upper extremity after stroke: a systematic review

Background: Therapeutic electrical stimulation (TES) is a therapeutic strategy aimed at improving impairments of the upper extremity in stroke. Objective: Assessment of the available evidence on the effect of TES of the affected upper extremity in improving motor control and functional abilities after stroke. Methods: A systematic literature search was performed to identify randomized controlled trials (RCTs) that have studied the effect of TES on motor control and functional abilities. The methodological quality of the studies was assessed systematically by two raters. The reported outcomes were examined to evaluate the effect of TES and to identify a possible relationship with patient characteristics, method of stimulation and methodological quality. When possible, effect sizes were calculated (Hedges' g). Results: Six RCTs were included. The methodological scores ranged from 7 to 16 (maximum 19). All studies assessed the effect on motor control, and four reported a positive effect. Effect sizes calculated in three studies ranged from 0.55 to 1.46. Only two studies assessed the effect on functional ability, one reported a positive effect. Subgroup analyses in two studies suggest a better response to stimulation in less severely affected patients. Apart from this, no relationship between effect and patient characteristics, method of stimulation or methodological quality could be detected. Conclusions: The present review suggests a positive effect of electrical stimulation on motor control. No conclusions can be drawn with regard to the effect on functional abilities.