This systematic review and meta-analysis found that electrical stimulation produced a small, but statistically significant improvement, in tight muscles (spasticity) for people recovering from stroke. The clinical importance of the improvement is uncertain. For example, electrical stimulation improved joint flexibility by an average of 2.87 degrees and spasticity improved by 0.3 on a 5 point scale. Stimulation was only found to work when used alongside other therapies, such as structured exercises or occupational therapy. NICE guidance currently only recommends electrical stimulation for drop foot after stroke. Cost effectiveness was not included in this review. For estimating total cost, an earlier study in 2012 calculated that the average annual treatment cost was about £3,000 per patient.
Why was this study needed?
More than 900,000 people in England are living with the effects of stroke, the fourth largest cause of complex disability in the UK. About a quarter of stroke sufferers experience spasticity, an increase in residual muscle tension or stiffness that leads to uncontrolled and awkward movements.
Neuromuscular electric stimulation is sometimes used to try and reduce spasticity in patients recovering from a stroke. It uses electrical stimuli, delivered through electrodes on the skin, to mimic signals from the nervous system and cause the spastic muscle to contract. Over time this may strengthen or retrain the muscle.
There have been a number of small trials of electric stimulation’s effectiveness, with conflicting results, and this review set out to combine the results to see if there was evidence for its use on spastic muscles after stroke.
What did this study do?
This was a systematic review of 29 randomised controlled trials, though just 14 were included in the meta-analysis. The other 15 trials were not used because of missing data or because they measured spasticity in a way that could not be analysed across studies. Trials compared the use of electric stimulation for spasticity of the arms or legs following stroke with a control group not exposed to electric stimulation. The regimen varied between trials. A typical regimen might be 30 minutes of stimulation, five times a week for three to four weeks, delivered in a hospital, without the need to stay overnight.
Trials used electrical stimulation alone or alongside other therapies, such as arm or leg exercises, Bobath (a problem solving approach for the assessment and treatment of movement disorders), occupational therapy, or botulinum toxin (Botox) therapy.
Standard systematic review methods were used. However many of the included studies were small (average size was 32 participants) and had a moderate to high risk of bias due to a lack of assessor blinding.
What did it find?
- Electrical stimulation improved joint flexibility by an average of 2.87 degrees (95% CI 1.18 to 4.56). Only trials that used electrical stimulation alongside other treatments were effective in the meta-analysis, and only those on the leg or elbow. Stimulation of the wrist showed no improvement.
- Electrical stimulation reduced spasticity by an average of 0.3 on a five point scale (95% confidence interval [CI] ‑0.58 to ‑0.03). Twelve of the trials used electrical stimulation alongside other treatments including botulinum toxin; the two trials that used electrical stimulation only showed no improvement in the meta-analysis. Only trials on the leg and ankle showed a significant reduction – stimulation of the wrist and elbow showed no statistically significant improvement.
- Trials not included in the meta-analysis gave varied results. Eight studies showed improvement in spasticity, while seven did not.
What does current guidance say on this issue?
NICE guidance on electrical stimulation published in 2009 recommends the use of electrical stimulation for drop foot (the inability to lift the foot and toes when walking) after stroke, provided that normal arrangements are in place for clinical governance, consent and audit.
A separate NICE guideline on stroke rehabilitation published in June 2013 recommends not to routinely offer people with stroke electrical stimulation for their hand and arm, unless as part of a trial.
What are the implications?
This review and meta-analysis suggests that electrical stimulation could be considered for the treatment of spasticity of the ankle after stroke. However the benefit was modest and underlying trials were small with high risk of bias. The review does not support routine use for the wrist. Also, most of the trials used electrical stimulation alongside other therapies, suggesting this is how it should be delivered. As there is not yet enough evidence with regards to its use as a stand-alone therapy or trials that compare it directly with other established treatments, such as botulinum toxin, the place of electrical stimulation in the treatment pathway is not yet clear.
NICE recommend electrical stimulation as an option for people with drop foot after stroke. An evaluation of botulinum toxin type A as a treatment for upper or lower limb spasticity after stroke will begin during late January 2017.
Cost effectiveness was not included in this review. However, a 2013 study calculated from standard 2012 hospital tariffs found that the average annual treatment cost for electrical stimulation per patient with dropped foot was £3,095.
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