This is an update of a systematic review1 that examined the effect of biofeedback in training lower limb activities after stroke. Biofeedback is equipment that transforms biological signals into an output that can be understood by the learner, providing information to the learner that is not consciously available. That is, biofeedback takes intrinsic physiological signals and makes them extrinsic, giving the person immediate and accurate feedback of information about these body functions. Biofeedback can be delivered through various senses, such as visual, auditory and tactile systems, and can provide information about the kinematics, kinetics and/or electromyography of activities. Biofeedback is available from medical equipment (eg, electromyography, force platforms and positional devices traditionally used in clinical practice); or from non-medical equipment that is increasingly available and used in stroke rehabilitation (eg, recreational games such as the Nintendo® Wii™). Biofeedback can be used in addition to verbal content; however, it also has the advantage that it can be set up for the patient to use when left to practise alone. However, biofeedback is not commonly used in stroke rehabilitation.2
The previous version of this review,2 which was published in 2011, examined biofeedback broadly in training lower limb activities after stroke, including trials where any form of biofeedback was provided during practice of the whole activity (rather than part of the activity), with outcomes measured during the same activity. Twenty-two trials met the inclusion criteria and were included in the review; however, meta-analyses demonstrated significant heterogeneity that was best explained by the quality of the included trials. When analyses were limited to higher quality trials (PEDro score > 4), biofeedback had a moderate effect in the short term (10 trials, 241 participants, SMD 0.49, 95% CI 0.22 to 0.75) compared with usual therapy, which was maintained beyond intervention (five trials, 138 participants, SMD 0.41, 95% CI 0.06 to 0.75), suggesting that learning had occurred. For a direct comparison of the effect of biofeedback interventions and usual therapy (which includes therapist communication), a post hoc meta-analysis was conducted of those trials where the amount of practice was equal in each group. That is, trials where the control group practised the same activity for the same amount of time as the experimental group, with the only difference being the substitution of biofeedback for therapist communication (presumably including feedback) in the experimental group. This meta-analysis demonstrated a moderate effect of a similar magnitude to the overall analysis (eight trials, 170 participants, SMD 0.51, 95% CI 0.20 to 0.83), suggesting that biofeedback is superior to therapist communication.
Since that review1 was published in 2011, a number of additional trials have been published that investigated the effect of biofeedback, warranting an update of the review. In particular, the potential of using recreational games in stroke rehabilitation has gained attention. The inclusion criteria for this updated review incorporated findings from the previous review. Specifically, this meant that the updated review would include any randomised trial investigating biofeedback from any signal (position, force, EMG) via any sense (visual, auditory, tactile), delivered concurrently during whole activity practice, compared with usual therapy that was practice of the same activity for the same amount of time in the control group with no biofeedback (but presumably with therapist communication), with outcome measures at the activity level and congruent with the activity trained. This ensures a true comparison of the effect of biofeedback compared with usual therapist communication. For the biofeedback intervention, inclusion in this update was based on whether the biofeedback delivered was concurrent rather than terminal feedback. This meant that commercially available recreational games would be included if the majority of the games played within the study delivered concurrent biofeedback, rather than inclusion based on the equipment itself. In order to make recommendations based on the highest level of evidence, this review included only randomised trials with a PEDro score > 4.
Therefore, the research questions for this systematic review were:
- 1. In adults following stroke, is biofeedback during the practice of lower limb activities more effective than usual therapy in improving those activities in the short term?
- 2. Are any benefits maintained beyond the intervention?