Volumetric analysis of thalamic nuclei in children with vasovagal syncope

This study aimed to investigate regional thalamic nuclei volumes in pediatric patients with vasovagal syncope (VVS) using automated MRI-based segmentation and compare these measurements with those of pediatric controls.

This retrospective case-control study included 76 pediatric patients with VVS and 34 age- and sex-comparable controls (total n = 110) who underwent brain magnetic resonance imaging. Thalamic nuclei were segmented using the FreeSurfer automated pipeline. Group differences were assessed using multivariate and univariate analyses of covariance adjusted for age, sex, and total intracranial volume. False discovery rate correction was applied for multiple comparisons.

Total right, left, and bilateral thalamic volumes did not differ significantly between groups (P = 0.802, P = 0.267, and P = 0.366, respectively). However, significant regional volumetric differences were identified in selected nuclei. Compared with controls, patients with VVS had larger left medial thalamic (P < 0.001), left pulvinar (P < 0.001), right pulvinar (P < 0.001), and right habenular (P < 0.001) volumes, and smaller right anterior ventral (P = 0.004), left mediodorsal (P = 0.003), and left intralaminar/midline (P = 0.012) volumes. After false discovery rate correction, corresponding q values were < 0.001, < 0.001, < 0.001, 0.002, 0.018, 0.017, and 0.043, respectively.

Children with VVS demonstrated regional volumetric differences in specific thalamic nuclei despite preserved total thalamic volume. The clinical and functional significance of these findings and their potential relationship to autonomic regulation remain uncertain. Further prospective studies incorporating functional and multimodal neuroimaging are warranted.