Is motor imagery effective for gait rehabilitation after stroke? A Cochrane Review summary with commentary

1Background

Stroke is a major cause of disability and mortality worldwide, and its prevalence and burden will likely increase with progressive ageing. The Global Burden of Disease study revealed that stroke was the leading cause of disability-adjusted life years among the neurological disorders (GBD 2016 Neurology Collaborators, 2019). The effects of a stroke include paralysis and muscle weakness in the lower limbs as well as a reduced balance and mobility. As a result, stroke survivors may have persistent difficulties in performing daily living activities and participating in social and community activities.

Independent, balanced gait is one of the main goals of all rehabilitation programs for individuals with reduced balance and mobility after stroke. Rehabilitation approaches in which motor control of the gait cycle is relearned by activation of the motor network are important for functional recovery. Motor imagery (MI), in which individuals engage in a cognitively rehearsed task in a safe, repetitive manner without actual execution of the movement, is a promising therapeutic technique. MI has been shown to be effective for the functional rehabilitation of lower limbs as well as the recovery of daily activities when applied in combination with conventional physical therapy (García Carrasco & Aboitiz Cantalapiedra, 2016). However, the optimal intervention protocols remain unclear. Furthermore, there is a high level of heterogeneity in the methodological quality of relevant studies and conflicting results regarding the effects of MI in the recovery of individuals after stroke (Guerra, Lucchetti, & Lucchetti, 2017). Recently, a new Cochrane Review by Silva et al. (2020), has specifically addressed the question of whether MI can improve gait among stroke survivors.

2Objective

The aim of this Cochrane Review was to explore whether MI had any treatment effects on improving ability to walk in stroke survivors.

3What was studied and methods

The population addressed in this review was adults aged 18 years and over with any type of stroke at any stage with varying degrees of severity (excluding mixed etiologies such as acquired brain injury). The intervention studied was MI alone or associated with action observation, functional gait training, or physical activity. The intervention was compared to other therapies (including conventional physical therapy), placebo, or no therapy. The primary outcome studied was “walking ability” as tested by walking speed (measured by biomechanical analysis or walking tests) and dependence on personal assistance (the level of dependence having been defining using reported data from walking related functional scales). The secondary outcomes were walking endurance, motor function, functional mobility, and adverse events. The review authors searched for randomized controlled trials that had been published up to February 2020.

4Results

The review included 21 studies with a total of 762 participants. Only 11 of the 21 studies had data which could be included in the meta-analyses. None of the included studies compared MI with placebo or no therapy, so the results all relate to the effect of MI compared to other therapies.

The review shows that:

5Conclusions

The authors concluded that, compared with other therapies, MI alone or associated with action observation or physical practice may increase walking speed within a short time period based on very low certainty evidence. They also found very low certainty evidence that MI was no more beneficial than other therapies in terms of motor function or functional mobility over a short time period. There was insufficient evidence to determine the effects of MI on mentioned outcomes in comparison to placebo or no intervention. MI seemed not to have any adverse effects. They further stated that caution is needed to interpret the conclusion as many studies had methodological limitations, small sample sizes, and wide confidence intervals.