We sought to compare the effects of action observation on arm and hand function after stroke with an alternative intervention or no intervention.
Stroke is one of the leading causes of death and disability worldwide. Individuals who survive a stroke have difficulty moving their arms, which can lead to problems with everyday activities and reduced participation in daily situations. Action observation (AO) is a physical rehabilitation approach proposed for arm rehabilitation, in which stroke survivor observes a healthy individual performing a task, either on video or in person, followed or not by execution of the same task. This safe technique can be performed without expensive and complicated equipment and requires minimal therapist supervision. Studies show that AO activates brain areas similar to those activated when performing the same action, and may favor movement recovery after stroke.
We identified 12 studies involving 478 individuals after stroke. Most used video sequences and AO followed by some form of physical activity, using a range of activities, with task complexity increased over the course of training or when it was easy for the participant to carry out. The evidence is current to October 2017.
Studies tested whether the use of AO compared with an alternative intervention or no intervention resulted in participants' improved ability to use their arms and hands, and found that AO therapy resulted in better arm (eight trials) and hand function (three trials).
Quality of the evidence
We classified the quality of the evidence as moderate for hand function, low for arm function and dependence on activities of daily living, and very low for motor performance and quality of life. Participants could engage in AO safely, since adverse events were not significant in scale or magnitude. The quality of the evidence for each outcome was limited due to the small number of study participants, low study quality, and poor reporting of study details.
We found evidence that AO is beneficial in improving upper limb motor function and dependence in activities of daily living (ADL) in people with stroke, when compared with any control group; however, we considered the quality of the evidence to be low. We considered the effect of AO on hand function to be large, but it does not appear to be clinically relevant, although we considered the quality of the evidence as moderate. As such, our confidence in the effect estimate is limited because it will likely change with future research.
Action observation (AO) is a physical rehabilitation approach that facilitates the occurrence of neural plasticity through the activation of the mirror-neural system, promoting motor recovery in people with stroke.
To assess whether action observation enhances motor function and upper limb motor performance and cortical activation in people with stroke.
We searched the Cochrane Stroke Group Trials Register (last searched 4 September 2017), the Central Register of Controlled Trials (24 October 2017), MEDLINE (1946 to 24 October 2017), Embase (1974 to 24 October 2017) and five additional databases. We also searched trial registries and reference lists.
Randomized controlled trials (RCTs) of AO, alone or associated with physical practice in adults after stroke. The primary outcome was upper limb motor function. Secondary outcomes included dependence on activities of daily living (ADL), motor performance, cortical activation, quality of life, and adverse effects.
Two review authors independently selected trials according to the pre-defined inclusion criteria, extracted data, assessed risk of bias, and applied the GRADE approach to assess the quality of the evidence. The reviews authors contacted trial authors for clarification and missing information.
We included 12 trials involving 478 individuals. A number of trials showed a high risk of bias and others an unclear risk of bias due to poor reporting. The quality of the evidence was 'low' for most of the outcomes and 'moderate' for hand function, according to the GRADE system. In most of the studies, AO was followed by some form of physical activity. Primary outcome: the impact of AO on arm function showed a small significant effect (standardized mean difference (SMD) 0.36, 95% CI 0.13 to 0.60; 8 studies; 314 participants; low-quality evidence); and a large significant effect (mean difference (MD) 2.90, 95% CI 1.13 to 4.66; 3 studies; 132 participants; moderate-quality evidence) on hand function. Secondary outcomes: there was a large significant effect for ADL outcome (SMD 0.86, 95% CI 0.11 to 1.61; 4 studies, 226 participants; low-quality evidence). We were unable to pool other secondary outcomes to extract the evidence. Only two studies reported adverse effects without significant adverse AO events.