Stroke rehabilitation based on cortical plasticity and the stage theory of motor output reorganization

Abstract

One of the most important objects of stroke rehabilitation is motor recovery from acute stage to chronic stage. Early rehabilitation intervention after stroke onset should be started during the critical time window phase. Herein, a theory concerning motor circuit reorganization in the cerebral cortex contributing to recovery following stroke is proposed. In the acute stage, motor recovery depends on residual corticospinal tract excitability from onset to 3 months (1st stage recovery). In the next stage, alternative output systems are used according to intracortical excitability depending on intracortical disinhibition at the peak of 3 months (2nd stage recovery). At 6 months and beyond training-induced synaptic strengthening becomes better established, and new networks are better reorganized (3rd stage recovery). Stroke rehabilitation programs commencing from the acute stage are required according to this stage theory. With each stage, selecting and performing the most effective rehabilitation programs is essential to successful recovery. Two motor recovery obstruction factors are indicated. One of them is Wallerian degeneration of the corticospinal tract. Early Wallerian degeneration of the corticospinal tract that is seen on diffusion-weighted MRI was reported. With the appearance of Wallerian degeneration at the acute stage, more attention should be directed to motor recovery inhibition. The second obstruction factor is the development of spasticity from the acute stage. Spastic paresis over time leads to immobilization of the paretic body part and chronic disuse of the paretic body part, which are avoidable through early rehabilitation intervention. Recently, various interventions were proposed for motor recovery dependent on the cortical plasticity theory. The combination of repetitive transcranial magnetic stimulation and intensive occupational therapy (NEURO-15) reported by Abo (2010) are recommended to recover hand functions at the chronic stage as 3rd stage recovery. The NEURO-15 is a promising method for stroke rehabilitation.