Fig 1.

Axial MR imaging shows temporal evolution of an acute cortical lesion in a patient with MELAS presenting with an acute stroke-like episode with left upper limb sensory loss. A, DWI (b = 1000) image from the day after symptom onset shows hyperintense intracortical signal in the middle-third of the right postcentral gyrus (hand/arm region of the primary somatosensory cortex). B, ADC image shows corresponding hypointense intracortical signal in keeping with diffusion restriction (white and black arrows). C, T2-weighted spin-echo image shows T2 hyperintensity in the deeper cortical layers and juxtacortical white matter (black arrow), with sparing of the superficial cortex (white arrow). D, Progress T2-weighted spin-echo image obtained 3 weeks later shows focal intracortical hypointense signal (black arrow) and mild volume loss, in keeping with pseudolaminar necrosis (black toenail sign).