Neuroanatomical correlates of neuropsychological dysfunction in pediatric pharmacoresistant epilepsy due to focal cortical dysplasia type II.

OBJECTIVE: Children and adolescents with pharmacoresistant epilepsy (PRE) show marked individual cognitive and emotional variability not fully accounted for by demographic or clinical variables. This exploratory pilot study characterizes neuroanatomical abnormalities and their relationships with neuropsychological functioning in a pediatric patient cohort with PRE due to type II focal cortical dysplasia (FCD). METHODS: Retrospective data were obtained from patients with histopathologically confirmed FCD II who completed presurgical evaluations including high-resolution 3T MRI and neuropsychological assessment. Voxel-based morphometric MRI postprocessing using the Morphometric Analysis Program (MAP18) provided age-adjusted quantitative characterizations of within-lesion MRI features Junction (gray-white matter junction blurring), Extension (abnormal gyration), and Thickness (cortical thickening in the regional lesion). Associations between MRI feature z-scores and cognitive domain composite scores were evaluated using Pearson correlation coefficients and multivariable linear and logistic regression models, controlling for seizure side and site. Lesion ROI volumes were also analyzed to evaluate their associations with MRI feature z-scores and neuropsychological function. RESULTS: We included 24 patients mean age = 13.8; 58% male with FCD IIa (n = 8; 33%) or FCD IIb (n = 16; 67%). Patients with FCD IIb had higher mean and maximum Junction z-scores compared to those with FCD IIa (Cohen's d = 1.00 and 1.07). Mean and maximum Thickness z-scores were negatively associated with attention (r = -0.32; r = -0.47) and general cognitive ability (GCA; r = -0.46; r = -0.41). Mean Thickness z-scores were also negatively associated with visuospatial skills (r = -0.34). In regression models, higher mean and maximum Thickness were associated with poorer GCA scores (estimate (se): -14.98 (6.88), p = 0.042; -5.76 (2.41), p = 0.027, respectively), and higher maximum Thickness was associated with worse attention scores (estimate (se): -6.02 (2.60), p = 0.032). Lesion volumes were not associated with MRI feature z-scores, cognition, self-reported mood or anxiety. SIGNIFICANCE: Our findings showed that lesional neuroanatomical abnormalities, particularly increased cortical thickness, were associated with poorer cognitive performance in pediatric patients with FCD II. Future research in larger, more diverse samples is needed to identify other factors contributing to neuropsychological variability in this population. PLAIN LANGUAGE SUMMARY: We studied 24 pediatric patients with pharmacoresistant epilepsy (PRE) and a confirmed diagnosis of focal cortical dysplasia type II (FCD II) to examine how MRI findings relate to thinking abilities. Patients with FCD IIb showed more pronounced MRI abnormalities than FCD IIa. Greater cortical thickening within the lesion was associated with difficulties in overall cognitive ability, attention, and visuospatial skills. After adjusting for seizure side and site, the relationships between cortical thickness and reduced overall cognitive ability and attention performance remained significant. Findings suggest that specific MRI features may serve as imaging markers of cognition in pediatric patients with FCD II.