Diffusion-weighted MRI diagnosis of pure motor stroke limited to primarily distal leg weakness.

Pure motor stroke (PMS) manifesting as distal weakness of a single extremity has rarely been described. The authors report a 59-year-old man with PMS who had primarily distal weakness of a single lower extremity, which to the authors' knowledge has not been previously described. Four days after onset, positive diffusion-weighted imaging confirmed that the small subcortical T2-weighted hyper-enhancing and nonenhancing T1-weighted hypo-intensity noted on magnetic resonance imaging (MRI) represented an acute PMS that was the cause of the patient's weakness. Increased awareness of this rare clinical presentation of PMS coupled with the promise of imaging the PMS with diffusion-weighted MRI should lead to earlier stroke intervention in these patients.