Stroke is a leading cause of disability and is typically associated with loss of motor function and reduced ability to perform activities of daily living. Electrical stimulation is recommended in clinical guidelines, but previous systematic reviews have not differentiated between different levels of patient involvement during the application of stimulation. This review aimed to estimate the effect of electrical stimulation without active involvement (neuromuscular electrical stimulation) compared to no electrical stimulation on activities of daily living and functional motor ability in adults with stroke.
A protocol that was specified a priori guided the methods. Sensitive searches performed in five databases (including PubMed and PEDro) and citation tracking were used to identify randomised controlled trials that were published in English. Participants were adults with clinically diagnosed stroke with any level of paresis severity or chronicity. Intervention was neuromuscular electrical stimulation administered to either the upper or lower limb through surface electrodes to elicit a visible muscle contraction with no active involvement from the patient plus usual rehabilitation. The comparator was usual rehabilitation only. The primary outcome was activities of daily living. Functional motor ability was the secondary outcome. Two independent reviewers selected trials for inclusion, evaluated risk of bias and extracted data. Any disagreements were resolved by consensus discussions or by a third reviewer. Risk of bias was evaluated using the PEDro scale and the Cochrane risk of bias tool. Certainty of evidence was not evaluated. Meta-analysis was used to pool the included trials to calculate standardised mean differences and 95% confidence intervals (CI). Three subgroup analyses were specified: location of stimulation (upper vs. lower limb); time post-stroke (acute vs. subacute vs. chronic); and, severity of paresis (mild vs. moderate vs. severe).
20 trials (956 participants) were included in the meta-analyses. Participants had a mean age of 62 years and were predominantly male (54%). The location of stimulation was the upper limb in 13 trials (primarily shoulder abductors, wrist extensors) and the lower limb in 7 trials (primarily ankle dorsiflexors). The time post stroke was acute (ie, < 7 days) for 3 trials, subacute (ie, 7 days to 6 months) for 13 trials and chronic (ie, > 6 months) for 4 trials. The severity of paresis was moderate in 5 trials and severe in 6 trials, with no trials investigating participants with mild paresis, 5 trials having a range of severities and 4 trials not reporting severity. The intervention was applied for 10-60 minutes/session, 1-4 sessions/day and 3-7 days/week for 3-12 weeks. Cyclic stimulation was typically used (frequency 30 Hz, fixed pulse width of 200-300 microseconds) with the amplitude adjusted to achieve a visible muscle contraction or joint movement. 13 trials scored 6/10 or more on the PEDro scale.
Compared to control, participants in the neuromuscular electrical stimulation groups had a mean of 0.41 standard deviations better activities of daily living score (95% CI 0.14 to 0.67; 10 trials; 428 participants) at follow-up. This translates to a mean of 9 points more on the 0-100 version of the Barthel Index (95% CI 3 to 15), the scale most used to measure activities of daily living in the review, for neuromuscular electrical stimulation compared to control. [Note: the baseline standard deviation for the Barthel Index from an inception cohort study and guidance from the Cochrane Handbook v6.1 were used to calculate this estimate]. Compared to control, the mean functional motor ability score was 0.15 standard deviations higher in the electrical stimulation groups (95% CI -0.13 to 0.43; 13 trials; 659 participants). Because the 95% CI for this estimate includes zero, the intervention may have no effect for this secondary outcome.
Subgroup analyses revealed that effects for activities of daily living were slightly larger for the upper limb (standardised mean difference 0.34, 95% CI 0.04 to 0.64; 6 trials; 266 participants) than for the lower limb (standardised mean difference 0.49, 95% CI -0.04 to 1.03; 4 trials; 162 participants). Effects were also slightly larger in subacute stroke (standardised mean difference 0.44, 95% CI 0.10 to 0.78; 7 trials; 310 participants) than in chronic stroke (standardised mean difference 0.35, 95% CI -0.14 to 0.84; 3 trials; 118 participants), and there were no trials for this outcome for acute stroke. Severe paresis (standardised mean difference 0.36, 95% CI -0.55 to 1.26; 3 trials; 142 participants) and moderate paresis (standardised mean difference 0.21, 95% CI -0.16 to 0.58; 3 trials; 119) had similar effects, with no data being available for mild paresis.
Neuromuscular electrical stimulation provided in addition to usual rehabilitation improved activities of daily living post stroke more than usual rehabilitation alone. This was particularly evident for the upper limb and in subacute stroke. Neuromuscular electrical stimulation had little impact on functional motor ability.
Kristensen MGH et al. Neuromuscular electrical stimulation improves activities of daily living post stroke: a systematic review and meta-analysis. Arch Rehabil Res Clin Transl 2022;4:100167