Neurofeedback from the brain’s cortical areas may boost the efficacy of imagery-based rehabilitation for stroke patients, a pilot study found.

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Neurofeedback from the brain’s cortical areas may boost the efficacy of imagery-based rehabilitation for stroke patients, a pilot study found.

When given neuronal feedback via near-infrared spectroscopy, 10 patients weakened on one side by subcortical stroke had a significantly greater functional gain in their hands and fingers than similar patients receiving sham feedback signals, according to Masahito Mihara, MD, PhD, of Osaka University Graduate School of Medicine in Osaka, Japan, and colleagues.

Even severely impaired patients had greater motor improvement compared with the group that received irrelevant feedback signals, they wrote in the study published online in Stroke: Journal of the American Heart Association.

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Accumulating evidence about the brain’s neural networks suggests that the same part of the brain is utilized during motor imagery and motor function.

“These findings support the notion that the motor imagery-based training may be used as a substitute for physical training,” Mihara and colleagues said.

Adding to the enthusiasm for using imagery to improve motor function is new data suggesting benefit for “forced use” of weak upper limbs that have atrophied because of “learned non-use,” researchers said.

The investigators noted the inconsistent results when motor-imagery based training has been employed, which calls for an “innovative intervention” such as neural feedback during imagery.

The problem with this type of feedback, researchers said, was that equipment is sometimes bulky, invasive, expensive or all three.

The tool used by Mihara and colleagues in this study was a near-infrared spectroscopy (NIRS) system. The infrared light easily passes through skin and skull bone, but does have some difficulty assessing activity deep in the brain, researchers pointed out.

The NIRS equipment is relatively small, making it ideal to measure real-life activity. It has a relatively poor spatial resolution up to few centimeters, but is suitable for clinical use, they said.

Researchers randomized 20 patients with first-time subcortical stroke equally to either real imagery-related hemoglobin signals or sham neurofeedback.

There was only one left-handed participant and one who was ambidextrous. The patients’ mean age was 58, and 12 were men.

Most patients experienced their stroke about 5 months prior to their participation in the study. Eleven patients showed right hemiparesis, and eight had hemorrhagic stroke.

All patients had an intense rehab schedule that included at least 60 minutes of physical therapy and 60 minutes of occupational therapy daily for 7 days a week. If needed, patients would utilize a speech therapist for an additional 60 minutes daily.

All patients got an introduction to imagery before the study. The received mental practice with motor imagery accompanied by neurofeedback three times a week for 2 weeks.

The primary outcome was improved motor skills of the hand and fingers using a common assessment test. Secondary outcomes were total upper limb function, including wrist, elbow, forearm and shoulder.

The goal of researchers was to enhance the premotor areas on the same side as the stroke through neurofeedback.

The average feedback signal intensity was 2.6 for the real group and 1.8 for the sham group. But there was no difference in average cortical signal intensity.

Before the neurofeedback, the real group had a hand/finger assessment score of 59.7. After the intervention, the score significantly improved to 68.6 (P<0.001). This was the primary outcome.

Researchers didn’t find the improvement in hand function to be correlated with imagery skills or the initial motor handicap.

Both groups enjoyed improvement in total upper body limb function, with significant group interaction, and in function of individual parts of upper the limbs, without significant group interaction.

A secondary analysis of severely impaired patients (seven from the real group, six from the sham group) showed a significant improvement in function only in the real group (P<0.001).

This proof-of-principle study supports the safety and efficacy of NIRS as a neurofeedback tool, but further studies are needed, the researchers concluded.

The study is limited by not recording patients’ practice of imagery on their own time, the small number of patients, and the sham group’s lower feedback values, which could have affected the efficacy of the neurofeedback.

The study received funding support from JSPS, Japan; Research Committee on the Improvement of Medical Care and the Organization of Supporting Systems for Patients with Rare Diseases; and Research Committee for Ataxic Disease from MHLW, Japan.

The researchers reported they had no conflicts of interest.

From the American Heart Association:

Primary source: Stroke: Journal of the American Heart Association              Source reference: Mihara M, et al “Near-infrared spectroscopy−mediated neurofeedback enhances efficacy of motor imagery−based training in poststroke victims: A pilot study” Stroke 2013; DOI: 10.1161/STROKEAHA.111.674507

By Chris Kaiser, Cardiology Editor, MedPage Today

Published: February 15, 2013
Reviewed by F. Perry Wilson, MD, MSCE; Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner