31 July 2014
A new study, published in the Neuroscientist journal, has suggested that chronically stimulating premotor areas (PMAs) of the brain is able to strongly promote motor recovery after a stroke. This could, for example, restore balance between the stroke and intact parts of the brain, while also establishing greater widespread connectivity.
Dr Ela Plow, from the Biomedical Engineering, Lerner Research Institute at the Cleveland Clinic Foundation, said it is crucial to understand who stimulation of the brain may benefit, how, and why.
Study author Dr Plow and her research team - David A Cunningham, Nicole Varnerin, and Andre Machado - used a conceptual model to suggest that other substrates, such as supplementary motor cortices that are more likely to survive damage, could be used to stimulate the brain. These substrates would, according to the authors, collaborate with areas of the brain that are intact and recruit them to aid with the recovery.
The researchers suggest that these substrates could be more useful in patients where great amounts of damage has been suffered, while they also opened up the possibility of using other substrates such as cerebellum, striatum and parietal cortices.
Addressing the challenge of strokes is crucial, not just because it is the leading cause of long-term adult disability, but also because this field of medicine pioneered the therapeutic potential of brain stimulation and, as such, has highlighted some conflicts, according to Dr Plow.
Dr Plow added: "Conflicting evidence in stroke has dampened the enthusiasm for brain stimulation witnessed across several hundred early studies in the last decade, limiting the potential of clinical outpatient or even inpatient delivery in the immediate future. Before starting another clinical trial and waiting to see if by chance the new study shows positive effects, we suggest re-evaluating and shifting perspective."
The research team outlined the potential of examining the journey of stimulation for stroke rehabilitation, from using homogeneous animal models, to early clinical studies where patients with greater sparing of motor cortices and spared output responded exceptionally well to stimulation of their residual cortex.
In contrast, larger clinical trials have shown that patients with more impairment, due to greater brain damage to cortices, received stimulation of the motor cortices but failed to uniformly augment outcomes of recovery.
With such conflicts in research, the study's authors found there was a great discordance between early and later, larger clinical studies resulted, saying that a "one-size-fits-all approach" is risking relying on pure chance for the results.
"Our intent here is to create a shift in perspective that forces us to broaden scope of stimulation from affecting a single target and a single mechanism to imagining how and what may remain to assume the potential for recovery in humans," Dr Plow continued.
The team suggested that targets may not even need to be uniform across all, because it may leave outcomes of trials to pure chance, but instead believe that systematically exploring substrates and defining successes and failures of each would "truly create personalised, not popular science".
Posted by Philip Briggs
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