Changes in serial optical topography and TMS during task performance after constraint-induced movement therapy in stroke: a case study

Abstract

The authors examined serial changes in optical topography in a stroke patient performing a functional task, as well as clinical and physiologic measures while undergoing constraint-induced therapy (CIT). A 73-year-old right hemiparetic patient, who had a subcortical stroke 4 months previously, received 2 weeks of CIT. During the therapy, daily optical topography imaging using near-infrared light was measured serially while the participant performed a functional key-turning task. Clinical outcome measures included the Wolf Motor Function Test (WMFT), Motor Activity Log (MAL), and functional key grip test. Transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) were also used to map cortical areas and hemodynamic brain responses, respectively. Optical topography measurement showed an overall decrease in oxy-hemoglobin concentration in both hemispheres as therapy progressed and the laterality index increased toward the contralateral hemisphere. An increased TMS motor map area was observed in the contralateral cortex following treatment. Posttreatment fMRI showed bilateral primary motor cortex activation, although slightly greater in the contralateral hemisphere, during affected hand movement. Clinical scores revealed marked improvement in functional activities. In one patient who suffered a stroke, 2 weeks of CIT led to improved function and cortical reorganization in the hemisphere contralateral to the affected hand.

Figure 1

Changes in optical topography measures over time. A. The laterality index of patient and control subject from baseline (Session 1) to completion of CI therapy (Session 9). B. Sum of oxy-hemoglobin concentrations in active channels of each hemisphere.

Figure 2

Example images from the patient. Shown are comparisons of posttreatment cortical activation using 3 different modalities. A. Optical topographic image of oxy-hemoglobin concentration during key turning with (affected) right hand superimposed on a 3-dimensionally reconstructed cerebral cortex of an MRI image of the patient. The red and blue shading in the topographic image indicate an increase and decrease in relative [oxy-Hb], respectively. In the left hemisphere (left side), contralateral to the moving hand, increase and decrease in [oxy-Hb] were observed in the precentral and superior frontal gyri, respectively. The 24 measurement channels are indicated by filled circles and numeric labels. B. The extensor digitorum communis MEP amplitude (mV) is displayed in a contour plot over the scalp surface as viewed from above, with x representing medial-lateral axis and y the anterior posterior axis. Positive x is to the right, y anterior, and the origin (0,0) is the scalp vertex (Cz in the EEG 10–20 system). Red indicates larger average MEP amplitude; blue indicates smaller average MEP amplitude. The top row is Pre-Rx, and the bottom row is Post-Rx. The affected hemisphere is on the left. Asterisks indicate location of hotspot. C. BOLD responses on a rendered brain indicating significant activation during right (affected) finger flexion/extension movements at a rate of 70% maximum compared to rest. In all 3 images the left hemispheric activation is shown in the left column, whereas the right hemispheric activity is depicted in the right column.

Figure 3

Changes in key grip and load forces after 2 weeks of CIT during the “lift and hold” task. Pretreatment forces (N) are shown in the top panel, whereas post-treatment grip forces are depicted in the bottom panel. Arrows indicate starting and ending points of lifting the transducer. See text for further explanation.