What motivated you and your team to revisit mirror therapy and what gaps in previous research were you hoping to address?

Previous reviews combined unilateral mirror therapy (involving only the non-affected limb with mirror feedback) and bilateral mirror therapy (using both limbs simultaneously), despite these being different interventions. In addition, control conditions were inconsistent and mirror therapy was often combined with other treatments. Our review separated unilateral and bilateral approaches and included only studies with matched practice in the control group to clarify the specific contribution of mirror feedback. 

Your review found that unilateral mirror therapy may improve motor recovery, while bilateral mirror therapy offers little or no additional benefit. Why do these two approaches produce such different outcomes? 

In unilateral mirror therapy, mirror feedback is the main active element and may directly stimulate motor areas related to the affected limb. In bilateral mirror therapy, the affected limb is already moving, so improvement seems to be driven mainly by practice itself, with little additional contribution from the mirror feedback. 

Based on your findings, how should physiotherapists prioritise or modify their use of mirror therapy in clinical practice? 

Our findings indicated that if physiotherapists choose to use mirror therapy, unilateral mirror therapy is the preferable approach. However, given the small overall effects observed, it should be used as an adjunct to therapy rather than as a primary intervention. 

Your review used strict criteria to ensure that the mirror illusion itself was the active component being tested. How did this methodological approach influence the conclusions compared with earlier reviews?

Our approach reduced the influence of confounding factors such as additional movement practice, combined interventions and heterogeneous intervention, while also maintaining controlled conditions. As a result, our conclusions support a more pragmatic interpretation of the contribution of mirror feedback to motor recovery. 

The improvements observed with unilateral mirror therapy were modest and often below the minimal clinically important difference. How should clinicians interpret this in terms of meaningful patient outcomes? 

The modest improvements observed suggest that unilateral mirror therapy is unlikely to produce large, meaningful changes on its own. These findings indicate that the average effect is small and often falls below the minimal clinically important difference. Therefore, clinicians should not consider mirror therapy as their first or only choice of intervention. Other interventions with strong evidence, based on intensive, task-specific training, should remain the priority in stroke rehabilitation.

What do you see as the most important directions for future research into mirror therapy and upper-limb rehabilitation after stroke? 

Evidence in neurological physiotherapy is often limited by small randomised trials. Given that unilateral mirror therapy may have a beneficial effect, larger, well-designed trials are needed to clarify its true impact. Future studies should also compare mirror therapy directly with training that is intensive, active and task-specific to determine its value relative to interventions already supported by strong evidence. 

>>Augusto Boening is a physiotherapist with a master’s degree in physiological sciences and a key research interest in neurological rehabilitation. He is currently a PhD candidate in physiological sciences at the Center of Health Sciences, Universidade Federal do Espírito Santo, Brazil.