July 23, 2019 | Two recently published journal articles by European authors argue for structural changes in neuromodulation approaches to stroke rehabilitation. The recommendations could hasten the commercialization of new stroke treatment devices.
Neurotechnology-based therapies, including brain-machine interfaces, robotics, and brain stimulation, will lead to largest treatment effects and success if they are tailored to the needs of individual patients, and used in combination, say the authors from the Wyss Center for Bio and Neuroengineering, EPFL, Scuola Superiore Sant’Anna, University of Geneva Faculty of Medicine, and Clinique Romande de Réadaptation. The paper, published in the journal Brain, calls for longitudinal clinical studies to show the rehabilitation benefits of individual therapies as well as the use of multiple complementary therapies used in combination over long time periods.
Lead author Martina Coscia, staff engineer at the Wyss Center said: “Our findings show that neurotechnology-aided upper limb rehabilitation is promising for severe chronic stroke patients. However, we also found that the ‘one size fits all’ approach doesn’t lead to the best outcome. We suggest a move towards a personalized combination of neurotechnology-based stroke rehabilitation therapies, ideally in a home-based environment where prolonged therapy is more feasible than in a clinic. We believe that by sequentially introducing stroke therapies according to individual progress, we could allow patients to continue their recovery beyond what is possible today.”
Friedhelm Hummel from EPFL said: “What we would like to see in the future are long-term trials in which multiple neurotechnology-based therapies are used within the same patient. We believe that this synergistic approach could uncover previously undiscovered treatment pathways for chronic stroke patients.”
The interdisciplinary research team is now starting a clinical trial to test these ideas. The trial uses a new experimental design with a personalized therapy approach using BCIs, robotics, FES, and brain stimulation specifically chosen to maximize treatment effects in each individual patient. The goal is to keep incrementally improving recovery by using new personalized, neurotechnology-based therapies in combination. The trial will start in Switzerland in summer 2019.
In the second paper, researchers from HSE University in Russia and the Max Planck Institute of Cognitive Sciences in Germany argue in Frontiers in Neurology that the existing approach to brain stimulation for rehabilitation after a stroke does not take into account the diversity of lesions and the individual characteristics of patients’ brains.
The authors argue that the main reason for the lack of effectiveness in neuromodulation approaches after a stroke is an inadequate selection of patients for the application of a particular brain stimulation technique. The existing approach does not take into account the diversity of lesions after a stroke and the variability of individual responses to brain stimulation as a whole. The researchers propose two criteria for selecting the optimal brain stimulation strategy. The first is an analysis of the interactions between the hemispheres. Now, all patients, regardless of the severity of injury after a stroke, are offered a relatively standard treatment regimen. This approach relies on the idea of interhemispheric competition.
“For a long time, it was believed that when one hemisphere is bad, the second, instead of helping it, suppresses it even more,” said Maria Nazarova, one of the authors of the article. “However, the fact is that this particular scheme does not work in many patients after a stroke. Each time it is necessary to check what the impact of the unaffected hemisphere is—whether it is suppressive or activating.”
The second criterion, scientists call the neuronal phenotype. This is an individual characteristic of the activity of the brain, which is “unique to each person like their fingerprints.” Such a phenotype is determined, first, by the ability of the brain to build effective structural and functional connections between different areas and second, the individual characteristics of neuronal dynamics, including its ability to reach a critical state. This is the state of the neuronal system in which it is the most plastic and capable of change.
Only by taking these criteria into account, the authors posit, can neuromodulation be brought to a new level and be effectively used in clinical practice. To do this, it is necessary to change the paradigm of the universal approach and select methods based on the individual characteristics of the brain of a particular person and the course of his or her disease.
