Resting state interhemispheric motor connectivity and white matter integrity correlate with motor impairment in chronic stroke

This is so blasted obvious, you need to look at the damage to the brain, that will correlate to impairments.
http://www.frontiersin.org/Journal/10.3389/fneur.2013.00178/full?utm_source=newsletter&utm_medium=email&utm_campaign=Neurology-w46-2013
Joyce L. Chen^1,2,3 and Gottfried Schlaug¹*

• ¹Neuroimaging and Stroke Recovery Laboratories, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
• ²Heart and Stroke Foundation Canadian Partnership in Stroke Recovery, Sunnybrook Research Institute, Toronto, ON, Canada
• ³Department of Physical Therapy, University of Toronto, Toronto, ON, Canada

Functional and structural reorganization in the brain occurs after stroke. The ability to predict motor outcomes may depend on patterns of brain functional and structural connectivity. We tested the hypothesis that alterations in motor transcallosal and corticospinal connections correlate with motor impairment in patients with chronic stroke. Eleven ischemic stroke patients underwent the Upper Extremity Fugl-Meyer (UE-FM) assessment, resting state functional magnetic resonance imaging, and diffusion tensor imaging (DTI). Twelve healthy control subjects underwent DTI. We assessed the temporal coupling in neural activity between interhemispheric motor cortex, and white matter integrity by means of fractional anisotropy (FA), in the transcallosal motor fibers and corticospinal tract. Partial correlation analyses were performed to determine whether these connectivity measures correlate with Upper UE-FM scores. Patients compared to controls had reduced FA in common voxels of transcallosal motor and ipsilesional corticospinal fibers. Within the patient group those with higher interhemispheric motor cortex connectivity and higher FA in the transcallosal motor fibers were less impaired. The results show that markers of functional and structural motor cortex connectivity correlate with motor impairment in the chronic stage of stroke.

More at link.