Improvement after constraint-induced movement therapy is independent of infarct location in chronic stroke patients

Abstract

Background and purpose: Disruption of the corticospinal tract at various locations in the brain has been shown to predict worse spontaneous motor recovery after stroke. However, the anatomic specificity of previous findings was limited by the categorical classification of infarct locations. Here we used computational methods to more precisely determine the specific anatomic locations associated with impaired motor ability. More important, however, our study also used these techniques to evaluate whether infarct location could influence motor outcomes after Constraint-Induced Movement therapy (CI therapy), a specific and controlled form of physical therapy.

Methods: Quantitative voxel-based analyses were used to determine whether infarct location could predict either initial motor ability or clinical improvement after CI therapy in chronic stroke patients.

Results: Although corona radiata infarcts were associated with worse in-laboratory motor ability at pretreatment, infarct location did not predict improvement in either the laboratory or the life situation after CI therapy.

Conclusions: The extent of improvement from CI therapy does not depend on the location of neurological damage, despite there being a pretreatment relationship between infarct location and in-laboratory motor ability. This dissociation could be explained by brain plasticity induced by CI therapy.

Figure 1

Infarct overlap map for 81 chronic stroke patients with mild to moderate upper extremity hemiparesis. Brains of patients with right arm hemiparesis were flipped left to right to equate for deficit side. (a) Axial cross-section through the basal ganglia. (b) Coronal cross-section through the primary motor area. (c) Sagittal cross-section through the medial temporal lobe. The colorbar indicates the number of patients with infarcts at each voxel. Infarcts were most frequently observed in the posterior limb of the internal capsule contralateral to the side of motor deficit (colored red).

Figure 2

Infarct location predicted performance on a laboratory-based measure of pre-treatment motor ability. (a) Results are displayed in coronal cross-sections through the primary motor area (shown in pink). (b) A map of t values from the quantitative voxel-based analysis: red-colored voxels indicate infarct locations that predicted poorer pre-treatment performance on the WMFT after correcting for multiple comparisons. (c) Map of Cohen’s d values indicating effect size for the quantitative voxel-based analysis. (d) Infarct overlap maps for the third of patients with the strongest performances (left), and weakest performances (right) on the WMFT before treatment.

Figure 3

Infarct overlap maps for the patients scoring in the upper third (a) versus lower third (b) on the MAL. In contrast to the pattern for WMFT scores, the location of the infarcts in patients with MAL scores in the upper versus lower thirds are similar. Results are displayed in coronal cross-section through the precentral sulcus.