Cortical lesions are of eminent clinical relevance in patients with multiple sclerosis (MS), since they have been associated with clinical decline and disease progression. Heretofore, cortical lesions were commonly assessed at a whole-brain level, and were found to correlate with EDSS. However, there is no evidence on correlations between the spatial distribution of cortical lesions and cognition. We hypothesize that the distribution of cortical lesions contributes to explaining the variance of both clinical and cognitive decline.
To further elucidate the spatial distribution of cortical lesions and assess their association with clinical and cognitive decline.
One-hundred-fourteen patients (59 RRMS, 37 SPMS, 16 PPMS, mean age 54.49 ±8.99, 76 female) underwent MRI (double inversion recovery (DIR) and 3D-T1), and neuropsychological assessment (BRB-N, Stroop, Memory comparison task). Raw cognition data were converted to Z-scores based on the control scores, and averaged over the domains. For each patient, cortical lesions were identified and delineated on DIR. The extent of lesioned cortex was measured and cortical lesion maps were generated to enable vertex-wise cortical lesion probability maps and correlations using FreeSurfer.
Cortical lesions were preponderantly situated in frontal and temporal lobes, as well as in the motor and anterior cingulate cortex. Significant clusters of vertex-wise correlations between cortical lesions and EDSS were primarily found for the motor cortex. Significant clusters of vertex-wise correlations between cortical lesions and cognition were primarily found for the frontal and temporal lobe.
The presence of frontal and temporal cortical lesions specifically predicted cognitive decline, while cortical lesions in the motor cortex were related to physical functioning. This confirms the hypothesis that the spatial distribution of cortical lesions contributes to explaining the variance of both clinical and cognitive decline. Further studies should investigate whether the location of cortical lesions is relevant to specific cognitive functions (e.g., memory or executive functioning).