Spatial functional distribution in the corticospinal tract at the corona radiata: a three-dimensional anisotropy contrast study.

The spatial functional distribution of the nerve fibers was investigated in the corticospinal tract at the level of the corona radiata. Thirteen patients with corona radiata infarction underwent axial single-shot echo planar diffusion-weighted magnetic resonance imaging using a 1.5 Tesla scanner. Image analysis used the three-dimensional anisotropy contrast (3DAC) method to demarcate the nerve fibers in the corticospinal tract. Axial 3DAC images demonstrated the corticospinal tract as a distinct area indicating nerve fiber integrity in all normal hemispheres and infarction as a dark or black area in affected hemispheres. Seven patients with upper extremity-dominant motor dysfunction had infarction located in the middle one third of the corticospinal tract. A patient with lower extremity-dominant motor dysfunction had infarction in the posterior one third. Five patients with equal motor dysfunction in the upper and lower extremities had infarction in both the middle and posterior one thirds of the corticospinal tract. The recovery of motor dysfunction at one month follow up correlated with the location of the corticospinal tract injury on the initial 3DAC images. The findings of the 3DAC images provide an indicator of the pattern and the recovery from acute and chronic motor dysfunction in patients with corona radiata infarction.