A single application of transcranial direct current stimulation (tDCS) profoundly improved impaired arm movements in patients after a stroke, according to a study published in the journal Brain Stimulation.

“In the lab, we have a robotic system that can be individually adapted to each patient, a kind of exoskeleton that enables them to move their paralyzed arm and perform tasks in a virtual environment,” explained study first author Toni Muffel, MSc, of the Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.

For the study, 24 patients with arm hemiparesis underwent tDCS while using the robotic system and interacting with virtual objects.

“In parallel, we measured how well, or how poorly, the brain stimulation helped the participants to perform the tasks,” Muffel said.

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According to the findings, tDS led to profound, although complex, performance modulations. On the whole, changes included simultaneous performance increases as well as noncanonical decreases. Dual tDCS induced more performance gains compared with anodal tDCS.

Nevertheless, patient responses varied with the task and electrode setup, with gains in certain parameters occurring at the expense of loss in other parameters. The lack of a uniformly beneficial pattern suggests tDCS therapy may need to individualized for each person.

“Our robotic system allows us to measure various motor functions simultaneously and thus gain a comprehensive picture of the stimulation effects. The data show that sensorimotor functions of the paralyzed arm are clearly influenced by tDCS,” said Bernhard Sehm, Dr med.

“However, we could not identify a uniform beneficial pattern across different patients. Instead, the changes in the brain areas varied depending on the task and the electrode placement. This means that in the future, patients will need to be closely examined before brain stimulation treatment in order to develop a targeted and individualized approach to their deficits. This simple but promising method of brain stimulation will then have a future in patient care.”

References

Muffel T, Shih PC, Kalloch B, Nikulin V, Villringer A, Sehm B. Differential effects of anodal and dual tDCS on sensorimotor functions in chronic hemiparetic stroke patients. Brain Stimul. 2022;15(2):509-522. doi: 10.1016/j.brs.2022.02.013

Brain stimulation shows beneficial effects for motor deficits following stroke. News release.