Distribution Pattern Analysis of Cortical Brain Infarcts on Diffusion‐Weighted Magnetic Resonance Imaging: A Hypothesis‐Generating Approach to the Burden of Silent Embolic Stroke

BACKGROUND: In patients with covert cerebrovascular disease or proximal source of embolism, embolic silent brain infarction may precede major stroke events. Therefore, characterization of particularly cortical silent brain infarction is essential for identifying affected patients and commencing adequate secondary prevention. This study aimed to investigate differences in the distribution pattern of cortical ischemic stroke lesions to assess potential predilection sites of cortical silent brain infarction. METHODS AND RESULTS: We prospectively included all consecutive patients with stroke presenting from January 1 to December 31, 2018. Diffusion‐weighted imaging lesions were used to generate voxel‐based lesion maps and assigned to atlas‐based cortical regions of interest in middle cerebral artery territories. Each region‐of‐interest lesion frequency was related to the respective region‐of‐interest volume to identify frequently affected and underrepresented cerebral cortex areas. Diffusion‐weighted imaging data for voxel‐based lesion maps were available in 334 out of 633 patients. Primary analysis revealed that small‐ (<0.24 cc) and medium‐sized (0.24–2640 cc) lesions distributed predominantly along regions associated with sensorimotor or language function. Detailed analysis within middle cerebral artery territories showed an approximated frequency of missed cortical stroke lesions of up to 67% in the right and 69% in the left hemisphere. In particular, the frontal, temporal, and occipital cortices were underrepresented. Larger lesion size and areas associated with higher cortical function led to hospital admission. CONCLUSIONS: Cortical brain infarcts in hospitalized patients are not dispersed equally but are predominantly located in brain structures associated with motor control and sensory and language function. Matching underrepresented cerebral cortex regions to symptoms not yet associated with stroke warrants further exploration.