Study Finds No Improvement in Motor Skills for Stroke Survivors with Brain Stimulation

Recent research presented at the American Stroke Association's International Stroke Conference 2025 has revealed that mild electrical brain stimulation does not enhance motor recovery in stroke survivors. The findings were shared during the conference held in Los Angeles from February 5-7, 2025.

Lead researcher, Dr. Wayne Feng from Duke University School of Medicine, expressed surprise at the results, which indicated that increasing the dose of electrical stimulation to 4 milliamps did not yield better outcomes than the lower doses or placebo treatments.

Stroke remains a significant health concern in the United States, ranking as the fifth leading cause of death and a major contributor to long-term disability. The condition can severely impact the ability to move arms and legs, thus affecting daily activities and overall quality of life. Motor impairment is recognized as the most prevalent complication following a stroke.

One established therapy, known as constraint-induced movement therapy (CIMT), involves restricting the movement of the unaffected arm to encourage the use of the affected side. While this method has proven effective in improving motor function and quality of life for certain stroke patients, it requires substantial commitment--typically six hours a day of intensive treatment, which can be daunting for many.

The study aimed to determine whether transcranial direct current stimulation (tDCS) could enhance the effectiveness of CIMT for stroke patients. Participants received weak electrical currents delivered through the skull to assess potential improvements in arm function.

The research, titled TRANSPORT 2, marks a significant multi-center stroke recovery study funded by the National Institutes of Health (NIH) StrokeNet. It evaluated 129 first-time ischemic stroke survivors who experienced persistent arm weakness yet retained some hand movement. Participants were randomly assigned to receive either sham stimulation, a low dose of 2 milliamps, or a higher dose of 4 milliamps alongside the CIMT.

After two weeks of treatment, researchers measured improvements across three key areas: motor impairment, functional ability, and quality of life. The results indicated that while all groups showed progress, the degree of improvement was comparable across all treatment categories, suggesting that the brain stimulation did not significantly augment the effects of CIMT.

Despite the lack of enhanced outcomes, the stimulation technique was deemed safe and tolerable for stroke patients. The study also highlighted practical feasibility for future clinical trials.

Some limitations were noted, including an uneven gender representation in the study groups, which may affect the results, and interruptions caused by the COVID-19 pandemic that impacted participant enrollment and data collection.

Dr. Feng expressed intentions for future trials to improve the methodology, including testing higher doses of stimulation, ensuring equitable gender distribution among participants, and refining the consistency in administering and evaluating treatments across the various clinical sites.

The patient group included an average age of 59 years, with a diverse demographic profile: 42% women, 53% white, 41% Black, and smaller percentages from Asian and multiracial backgrounds. The study spanned 15 medical centers across 11 states and the District of Columbia, with participants involved for approximately four months.

Clinical outcomes were assessed using validated measures, including the Fugl-Meyer Upper-Extremity Scale for motor impairment, the Wolf Motor Functional Test for motor function, and the Stroke Impact Scale Hand Subscale for quality of life, with evaluations taking place immediately post-treatment and again at one and three months later.

Overall, the combination of brain stimulation and intensive rehabilitation was safe and feasible, paving the way for additional research in stroke recovery strategies.