Adam de Havenon, MD

Dang C, Liu G, Xing S, Xie C, Peng K, Li C, et al. Longitudinal Cortical Volume Changes Correlate With Motor Recovery in Patients After Acute Local Subcortical Infarction. Stroke. 2013

Advances in MRI technique, software analysis, and increases in field strength have allowed researchers to perform detailed volumetric analysis of the brain. Since the 19th century, when Waller started lesioning rat brains, we have known that cortical damage, such as ischemic stroke, leads to degeneration of connected sub-cortical axons, but more recent research has shown that the neuron is equally dependent on its axon, as are neurons in remote locations. The study by Chao Dang et al. looks at fifteen patients with acute subcortical unilateral infarct in the anterior circulation who underwent structural MRI and clinical assessment 3 times over a 12-week period and compared the results to controls. They used voxel-based morphometry (VBM) to quantify changes in global GM volume and then picked specific volumes of interest (VOIs) related to motor function and compared changes in VOIs to scores on two measures of patient functional outcome, the Fugl-Meyer scale score and the Barthel Index. 

The results of the changes in global GM volume were mixed, but the overall trend was a decrease in GM in the ipsilesional side and increase on the contralateral side. Three VOIs had a statistically significant change, with a decrease in the ipsilateral SMA and contralateral insula, and increase in the contralateral SMA. Both the SMA decrease and increase were correlated with improved outcome. 

It is not clear why the decrease in ipsilesional SMA GM would correlate with better outcome; and wouldn’t we expect patients who score higher on functional testing to have an increase in the contralateral SMA GM, as they were probably using that side more. The immediate clinical relevance of these findings is limited, but continued advances in this field should ultimately lead to some interesting trials involving novel rehabilitation techniques.