Matching accuracy in hemiparetic cerebral palsy during unimanual and bimanual movements with (mirror) visual feedback.
Mirror feedback only improves reaching for kids with hemiparetic CP who start with big errors—check baseline accuracy first.
01Research in Context
What this study did
Researchers asked children with hemiparetic cerebral palsy to reach for targets. Kids tried the task three ways: with one hand, with both hands, and with both hands while watching a mirror that showed the stronger arm in place of the weaker one.
Each child did many reaches while cameras tracked hand position. The team measured how close the weaker arm came to the target every time.
What they found
Using both hands at once cut reaching error for the whole group. Adding the mirror helped only some kids—13 out of 23 did better, but the rest stayed the same.
The mirror only helped children who started with the biggest errors. Kids who already reached fairly well gained nothing from the reflection.
How this fits with other research
Diz et al. (2011) ran a similar mirror test the year before. Instead of reaching, kids matched elbow angles while watching the mirror. Again, the mirror improved accuracy, showing the idea holds for both still and moving tasks.
Sharp et al. (2010) looked at muscle activity during the same mirror setup. Less muscle effort was needed when the mirror was in place. Together, the three papers show mirror feedback can cut both error and strain.
Visicato et al. (2015) reviewed dozens of reaching studies in cerebral palsy. They report that every child moves differently and that task setup changes outcomes. The mirror-only-helps-some pattern in the 2012 study matches that wider picture.
Why it matters
Before you add mirror therapy to a session, run a quick baseline. Ask the child to reach for three targets and record the error. If misses are large, set up a mirror and practice bimanual reaches. If misses are small, skip the mirror and spend time on other goals. This simple screen saves minutes and keeps therapy focused on what actually helps each child.
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02At a glance
03Original abstract
In the present study participants with Spastic Hemiparetic Cerebral Palsy (SHCP) were asked to match the position of a target either with the impaired arm only (unimanual condition) or with both arms at the same time (bimanual condition). The target was placed at 4 different locations scaled to the individual maximum reaching distance. To test the effect of mirror visual feedback of the less-impaired arm on the matching accuracy, an opaque screen or a mirror was placed in between the arms which masked vision of the impaired arm. Absolute endpoint error was smaller in the bimanual condition compared to the unimanual condition, but there was no effect of mirror visual feedback. Inspection of the individual data, however, showed that 13 out of 23 participants did experience a positive effect of mirror visual feedback. A positive correlation between the baseline error (screen) and the improvement in accuracy with mirror visual feedback seems to suggest that individuals with lower proprioceptive accuracy in the baseline condition may benefit more from mirror visual feedback. Together these findings indicate that bimanual therapy and therapy with mirror visual feedback might be valuable approaches for rehabilitation for a subset of the individuals with SHCP.
Research in developmental disabilities, 2012 · doi:10.1016/j.ridd.2012.06.004