Researchers at the University of Alabama, USA, and the Friedrich-Schiller University, Jena, Germany have originated a new stroke rehabilitation technique termed constraint-induced movement therapy (CI therapy). It involves restricting any movement in the unaffected arm for nearly all the waking hours, and giving intense repetitive training exercises for the affected arm, 6 hours daily for 2-3 weeks. (A similar technique is used an affected leg, but without constraint of the other leg.) Several small studies have shown that CI therapy is very effective in chronic stroke patients, i.e. when used after the acute phase has passed and the extent of the paralysis is fixed; the benefits gained persists for 6 months, at least.

The study summarized here measured electrical changes on the surface of the brain, on both the affected and the unaffected side, before and after the treatment period. Thirteen stroke patients who had limb paralysis for an average of 5 years were included. Their average age was about 55. A scale called the Motor Activity Log (MAL) was used to measure the affected arm's use in 20 common, important activities of daily living; testing was done before and at intervals up to 6 months after therapy. The electrical activity on the surface of the brain cortex responsible for limb movement was measured using a technique called transcranial magnetic stimulation (TMS) mapping, done at the same times as MAL measurements. CI therapy was given for 12 days, with constraint and exercise as outlined above.

The MAL scores, which showed the benefits of the therapy, increased significantly from the day before treatment to the day after treatment; this improvement was maintained at 6 months after treatment.

The electrical activity of the brain surfaces was interesting. On the day before treatment, there was 40% less activity on the affected side than on the non-affected side, a significant difference. However, by the first day after CI therapy this relationship had reversed, with an almost 40% difference in favor of the affected side. Four weeks after treatment, the activity on the affected side was still significantly greater than before therapy, while at 6 months both sides were practically equal.

This study is the first to demonstrate a long-term change in brain electric function in association with a rehabilitation technique that produces improvements in movement after stroke injury. It is important for two reasons. First, it provides evidence that a successful therapy produces electrophysiological changes in the brain indicating that neurons can indeed be switched back on again after an injury like a stroke. Second, the electric changes that persist for 6 months show that CI therapy does indeed offer a definite improvement that can be backed up by measurable effects on brain function, other than just improved movements.

Source

Treatment-induced cortical reorganization after stroke in humans
J. Liepert, H. Bauder, HR. Miltner,  et al., Stroke, 2000, vol. 31, pp. 1210--1216