Preservation of the integrity of the corticospinal tract in a patient with medulla infarct.

Diffusion tensor tractography allows the visualization of the corticospinal tract (CST). In the current study, we attempted to demonstrate the preservation of the integrity of the CST within an infarct in a hemiparetic patient with a medulla infarct. A 76-yr-old male patient showed severe paralysis of the left extremities at stroke onset. Over the 4 mos following onset, motor functions of the affected extremities rapidly recovered to a normal state. On the diffusion tensor tractography taken at 1 wk after onset, the tract of the both hemispheres descended through the known CST pathway. Notably, the tract of the affected (right) hemisphere descended through the anterior portion of the infarct in the medulla. The motor-evoked potential obtained from the affected (left) hand muscle had the characteristics of the CST. In conclusion, we demonstrated that the integrity of CST had been spared in the anterior portion of the medulla infarct by using diffusion tensor tractography and transcranial magnetic stimulation.