Motor recovery and cortical reorganization after constraint-induced movement therapy in stroke patients: A preliminary study

Constraint-induced movement therapy (CIMT) is a physical rehabilitation regime that has been previously shown to improve motor function in chronic hemiparetic stroke patients. However the neural mechanisms supporting rehabilitation-induced motor recovery are poorly understood. The goal of this study was to assess motor conical reorganization after CIMT using functional magnetic resonance imaging (fMRI). In a repeated-measures design, 4 incompletely recovered chronic stroke patients treated with CIMT underwent motorfunction testing and fMRI. Five age-matched normal subjects were also imaged. A laterality index (LI) was determined from the fMRI data, reflecting the distribution of activation in motor cortices contralateral compared with ipsilateral to the moving hand. Pre-intervention fMRI showed a lower LI during affected band movement of stroke patients (LI = 0.23 +/- 0.07) compared to controls (LI unaffected patient band = 0.65 +/- 0.10; LI dominant normal hand = 0.65 +/- 0.11; LI nondominant normal band = 0.69 +/- 0.11; P < 0.05) due to trends toward increased ipsilateral motor conical activation. Motor function testing showed that patients made significant gains in functional use of the stroke-affected upper extremity (detected by the Motor Activity Log) and significant reductions in motor impairment (detected by the Fugl-Meyer Stroke Scale and the Wolf Motor Function Test) immediately after CIMT and these effects persisted at 6-month follow-up. The behavioral effects of CIMT were associated with a trend toward a reduced LI from pre-intervention to immediately post-intervention (LI = -0.01 +/- 0.06; P = 0.077) and 6 months post-intervention (LI = -0.03 +/- 0.15). Stroke-affected band movement was not accompanied by mirror movements during fMRI, and electromyographic measures of mirror recruitment under simulated fMRI conditions were not correlated with LI values. These data provide preliminary evidence that gains in motor Junction produced by CIMT in chronic stroke patients may be associated with a shift in laterality of motor conical activation toward the undamaged hemisphere.