Key messages

• Electrical stimulation is effective in increasing strength in people with weakness after stroke.

• As the person regains movement and can attempt everyday activities, there is only a small benefit from adding electrical stimulation during the practice of those activities.

• Additional trials are needed that compare electrical stimulation for weakness with another strengthening treatment.

What is electrical stimulation?

In electrical stimulation, pads called electrodes are placed on the skin and connected to a small machine to deliver an electrical current to a muscle so that the muscle contracts.

How is electrical stimulation used after stroke?

Electrical stimulation can be used in two ways after stroke. Cyclical electrical stimulation (CES) can be used on weak muscle(s) to improve muscle strength. Functional electrical stimulation (FES) can be used on muscle(s) during the performance of an activity to improve the performance of that activity.

What did we want to find out?

We wanted to find out if CES is better than no treatment or another strengthening treatment at increasing muscle strength, and if FES is better than no treatment or practice of the same activity without stimulation at improving the performance of that activity. We also wanted to know the effect of electrical stimulation on participation in the community and quality of life, and if it is associated with any unwanted effects.

What did we do?

We searched for studies looking at the effects of CES or FES in adults following stroke. We then compared and summarised the results of the studies and rated our confidence in the evidence based on factors such as study methods and size.

What did we find?

We found 89 studies involving a total of 2905 adults who had experienced a stroke. Thirty-four trials with 1176 participants looked at CES, and 55 trials with 1729 participants looked at FES.

• In 23 studies, CES showed a moderate benefit in muscle strength compared to no treatment. Twenty of these studies also showed an improvement in performance of everyday activities, such as reaching or walking.

• Only one study compared CES to another strengthening treatment, and the results were unclear.

• In 12 studies, FES showed a moderate improvement in the ability to perform activities compared to no treatment.

• In 35 studies, FES showed only a small additional benefit compared to practising the same activity without stimulation.

• Many studies did not report whether people experienced unwanted effects from the electrical stimulation. Among those that did, few unwanted effects were reported, and none were serious.

• Very few studies looked at whether electrical stimulation improved participation in the community or quality of life. As a result, we cannot say whether it has an effect on these outcomes.

What are the limitations of this evidence?

We are confident to moderately confident that CES is effective compared to no treatment, and that FES is effective compared with no treatment, but that FES is little better than practice alone. Where we were only moderately confident in the evidence, this was due to the small numbers of people in the studies.

We are only moderately confident that CES and FES do not result in unwanted effects, as not many studies reported this information.

We have very low confidence in the evidence for CES compared with another form of strengthening due to the small number of studies in this comparison. We also have very low confidence in the evidence for the effects of electrical stimulation on participation in the community and quality of life, as these outcomes were not often considered.

How up-to-date is this evidence?

The evidence is current to December 2024.