Reflections on Mirror Therapy A Systematic Review of the Effect of Mirror Visual Feedback on the Brain

How many more research articles repeating the same things on this subject need to be written before our stroke leaderships steps up and declares that there already is a written protocol on this and to stop writing on this. Well never, since we have NO stroke leadership and NO stroke rehabilitation protocols. You are fucking screwed and what stroke leadership there is doesn't care.
Mirror training has been considered useful since at least 1999. I've written 30 posts on mirror therapy since 2012. But since nobody is listening to me, nothing has been done about writing a fucking simple stroke protocol on this. Do not do this on your own, way too dangerous.

Reflections on Mirror Therapy A Systematic Review of the Effect of Mirror Visual Feedback on the Brain

1. Frederik J. A. Deconinck, PhD1,2
2. Ana R. P. Smorenburg, PhD3
3. Alex Benham, PhD4
4. Annick Ledebt, PhD5
5. Max G. Feltham, PhD6
6. Geert J. P. Savelsbergh, PhD5

1. ¹Ghent University, Ghent, Belgium
2. ²Manchester Metropolitan University, Manchester, UK
3. ³Burke-Cornell Medical Research Institute, White Plains, NY, USA
4. ⁴Bradford Institute for Health Research, Bradford, UK
5. ⁵VU University, Amsterdam, Netherlands
6. ⁶University of Birmingham, Birmingham, UK

1. Frederik J. A. Deconinck, Ghent University, Faculty of Medicine and Health Sciences, Department of Movement and Sports Sciences, Watersportlaan 2, Gent 9000, Belgium. Email: Frederik.Deconinck@UGent.be

 

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Abstract

Background. Mirror visual feedback (MVF), a phenomenon where movement of one limb is perceived as movement of the other limb, has the capacity to alleviate phantom limb pain or promote motor recovery of the upper limbs after stroke. The tool has received great interest from health professionals; however, a clear understanding of the mechanisms underlying the neural recovery owing to MVF is lacking.  

Objective. We performed a systematic review to assess the effect of MVF on brain activation during a motor task. Methods. We searched PubMed, CINAHL, and EMBASE databases for neuroimaging studies investigating the effect of MVF on the brain. Key details for each study regarding participants, imaging methods, and results were extracted.  

Results. The database search yielded 347 article, of which we identified 33 suitable for inclusion. Compared with a control condition, MVF increases neural activity in areas involved with allocation of attention and cognitive control (dorsolateral prefrontal cortex, posterior cingulate cortex, S1 and S2, precuneus). Apart from activation in the superior temporal gyrus and premotor cortex, there is little evidence that MVF activates the mirror neuron system. MVF increases the excitability of the ipsilateral primary motor cortex (M1) that projects to the “untrained” hand/arm. There is also evidence for ipsilateral projections from the contralateral M1 to the untrained/affected hand as a consequence of training with MVF.  

Conclusion. MVF can exert a strong influence on the motor network, mainly through increased cognitive penetration in action control, though the variance in methodology and the lack of studies that shed light on the functional connectivity between areas still limit insight into the actual underlying mechanisms.

Introduction

Often a source of fascination, or perhaps frustration, optical illusions have captivated people since ancient times. For instance, curved surfaces and the absence of right angles in archaic Greek temples suggest that its architects attempted to optically correct the illusion of slanted columns or curved tympanums; however, others believe these features may serve engineering purposes or reflect aesthetic preference.¹ As much as they are a source of excitement, for neuroscientists optical illusions are considered a backdoor into people’s mind and provide an excellent way to study the neural mechanisms underlying perception and action.²

Interestingly, although optical illusions are known to deceive the individual, the false reality may fool the brain, such that the outcome is beneficial. One such an illusion is the mirror illusion, which has been found to have therapeutic benefits over the past 2 decades. When a mirror is placed, along the midsagittal plane in between the 2 limbs, the reflection of the limb in front of the mirror is superimposed on the contralateral limb. Any motion of the limb in front of the mirror induces the illusion of 2 synchronously moving limbs. After Ramachandran and his colleagues found that this illusion could alleviate phantom pain in a proportion of the patients,³ mirror visual feedback (MVF) was introduced as a neurorehabilitation tool to treat other unilateral pain disorders, such as complex regional pain syndrome (CRPS). In addition, the paradigm is now used to promote motor recovery (eg, in hemiparetic patients or after hand surgery).

Despite its widespread use in neurorehabilitation and the claims that MVF therapy would lead to neuroplastic changes, there is no consensus about the underlying mechanism and speculation often lacks the neuroscientific proof. The aim of this review is therefore to bring together current knowledge on the effect of MVF on the brain as has been described in neuroimaging studies, in order to explore potential processes underlying the beneficial clinical effects of MVF. To acquaint the reader with MVF and its current applications, we will first revisit Ramachandran’s rationale for MVF, followed by a narrative review of the clinical neurorehabilitation research that followed in his footsteps. At the end of this section, we introduce 3 hypotheses that have been proposed to explain the positive effects related to MVF. Part 2 provides a systematic review and discussion of studies that examined the effect of MVF on brain activation patterns using neuroimaging or electrophysiological techniques. Finally, in Part 3 we discuss the findings of the systematic review in relation to the hypotheses introduced in Part 1 and we identify where further research is required.