Injury of the Corticofugal Tract from the Secondary Motor Area in Middle Cerebral Territory Infarction: A DTI Study

Background and Purpose Middle cerebral artery (MCA) territory infarction commonly induces a variety of motor function deficits because it involves multiple descending motor pathways, including the corticospinal tract (CST) and corticofugal tract (CFT). Despite the importance of the MCA territory for motor function, there is currently insufficient evidence regarding an injury of the CFT from the secondary motor area in MCA territory infarctions. We investigated injury of the CFT from the secondary motor area and CST in patients with MCA using diffusion tensor tractography (DTT). Methods Thirty-five patients with MCA territory infarctions and 30 controls were recruited. DTT parameters, including fractional anisotropy (FA) and tract volume (TV), of the CST and CFTs from the dorsal premotor cortex (dPMC) and supplementary motor area (SMA), were analyzed. Results In the affected hemisphere, the FA values of the CFTs from the secondary motor areas and CST were significantly lower than those in the unaffected hemisphere and control groups. Additionally, the TV of the CFTs from the dPMC and SMA were significantly lower than those from the unaffected hemisphere. Conclusion We observed concurrent injury to the CFTs from the secondary motor area and CST after MCA territory infarction. Our findings explain the neural mechanisms underlying motor weakness and limb kinetic apraxia in patients with MCA.