Constraint-induced movement therapy results in increased motor map area in subjects 3 to 9 months after stroke

Abstract

Background: Constraint-induced movement therapy (CIMT) has received considerable attention as an intervention to enhance motor recovery and cortical reorganization after stroke.

Objective: The present study represents the first multi-center effort to measure cortical reorganization induced by CIMT in subjects who are in the subacute stage of recovery.

Methods: A total of 30 stroke subjects in the subacute phase (>3 and <9 months poststroke) were recruited and randomized into experimental (receiving CIMT immediately after baseline evaluation) and control (receiving CIMT after 4 months) groups. Each subject was evaluated using transcranial magnetic stimulation (TMS) at baseline, 2 weeks after baseline, and at 4-month follow-up (ie, after CIMT in the experimental groups and before CIMT in the control groups). The primary clinical outcome measure was the Wolf Motor Function Test.

Results: Both experimental and control groups demonstrated improved hand motor function 2 weeks after baseline. The experimental group showed significantly greater improvement in grip force after the intervention and at follow-up (P = .049). After adjusting for the baseline measures, the experimental group had an increase in the TMS motor map area compared with the control group over a 4-month period; this increase was of borderline significance (P = .053).

Conclusions: Among subjects who had a stroke within the previous 3 to 9 months, CIMT produced statistically significant and clinically relevant improvements in arm motor function that persisted for at least 4 months. The corresponding enlargement of TMS motor maps, similar to that found in earlier studies of chronic stroke subjects, appears to play an important role in CIMT-dependent plasticity.

Figures

Figure 1

Effect of constraint-induced movement therapy on Wolf Motor Function Test (WMFT) collected at baseline, after 2 weeks, and at 4-month follow-up. A, Mean of time-based evaluations. B, Mean of force-based measure. C, Mean of force-based measure (grip strength, kg). Note that the experimental group (black dots) showed improvement in all performance measures after 2 weeks and at 4-month follow-up compared with the control group (white dots). Grip force showed significant improvement compared with the control group (P = .049).

Figure 2

Longitudinal changes in transcranial magnetic stimulation (TMS) motor map area (3A) on the ipsilesional hemisphere. Note that there was a trend for an increased map area when comparing experimental (black dots) and control groups (P = .053) over a 4-month period.

Figure 3

Longitudinal changes in transcranial magnetic stimulation (TMS) motor map area of 2 representative subjects. The grid size is 1 cm and (0,0) is Cz in the 10-20 EEG system. Motor responses at each scalp position are color-coded by motor evoked potential size (relative to the maximal response). Increased TMS motor map area of ipsilesional hemisphere was observed in a subject assigned to the experimental group over a 4-month period (top diagrams) whereas the map area of the subject assigned to the control group tended to decrease (bottom diagrams).

Figure 4

Longitudinal changes in silent periods in the ipsilesional hemisphere. No significant changes were observed when comparing experimental (black) and control (white) groups.