Brain Stimulation Shows Promise in Chronic Stroke Recovery

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October 25, 2007 (Washington, DC) — Noninvasive transcranial direct current stimulation (TDCS) significantly improves recovery in severely affected chronic stroke patients and may provide a new therapeutic approach to facilitate recovery, new research suggests.

Presented here at the 132nd Annual Meeting of the American Neurological Association, the randomized controlled pilot study showed that a combination of TDCS and occupational therapy (TDCS plus OT) 1 hour per day for 5 days produced up to a 3-fold improvement in motor outcomes compared with combination therapy with sham stimulation and OT in patients with moderate to severe stroke-related hemiparesis.

\"With [TDCS and OT] we saw quite a significant and dramatic improvement in range of motion and in Fugl-Meyer upper-extremity scores compared with combination therapy with sham [stimulation] and OT. There was also a significant residual effect at 1 week. We also observed a residual effect at 1 month, but due to the small number of patients, this did not reach [statistical] significance,\" principal investigator Gottfried Schlaug, MD, from Beth Israel Deaconess Hospital, in Boston, Massachusetts, told Medscape Neurology & Neurosurgery.

Virtual Lesion

According to Dr. Schlaug, the hypothesis for using brain stimulation to augment recovery lies in the fact that a stroke creates an imbalance in the normal communication of the brain's hemispheres such that the unaffected hemisphere becomes functionally dominant and inhibits the damaged hemisphere.

TDCS can lead to reversible shifts in cortical excitability and has the potential to interfere in these abnormal pathophysiological processes. Therefore, the investigators used it to create a \"virtual lesion,\" or \"block\" the influence of the healthy hemisphere and depress inhibition on the affected side of the brain. The simultaneous use of OT allowed them to increase plastic changes in the brain and improve function in the paretic hand.

The study included 10 chronic stroke patients who had experienced a stroke a minimum of 6 months prior to study enrolment. Mean Fugl-Meyer upper-extremity scores were 28.3 out of a maximum of 66.

The primary outcome measure was a change in range of motion across 3 joints and the percentage of active over passive movements as well as changes in the Fugl-Meyer upper-extremity score.

Subjects were randomized to receive either TDCS plus OT or sham stimulation plus OT for 5 consecutive days. Each subject also underwent several motor assessments as well as 2 functional magnetic resonance imaging (fMRI) studies while performing motor tasks — 1 at baseline and 1 after the study intervention.

Recovery Potential Unknown

The study was a crossover design, so that after assessment of \"long-term\" effects at 3 weeks, patients were then switched to receive the opposite intervention they had at the start of the study, with the same assessment and follow-up protocols.

According to Dr. Schlaug, there were significant differences between real- and sham-stimulated patients, with about a 2.5- to 3-fold difference in range of motion and even stronger results in the Fugl-Meyer upper-extremity scores.

According to Dr. Schlaug, TDCS plus OT produced a 15.5% improvement, or 5-point absolute improvement in Fugl-Meyer scores, compared with a 1.2-point absolute improvement with sham stimulation. In addition, there was a residual effect of therapy at 1 week, and even after 1 month none of the patients returned to baseline.

\"Our goal was simply to achieve a difference between real stimulation and occupational therapy and sham stimulation and occupational therapy, and so we limited therapy to just 5 days. At this point we don't know what the maximal potential benefit might be,\" said Dr. Schlaug.

Dr. Schlaug said his team's next research steps include examining the impact of long-term therapy with TDCS plus OT in stroke recovery and identifying potential predictors of recovery to help determine which patients are most likely to benefit from TDCS.

The study was supported by the National Institutes of Health.