The role of the precuneus in dissociative seizures: A structural neuroimaging study

The neurobiology and neuropsychology of dissociative seizures is increasingly well understood, but a gap remains in understanding the neurobiological underpinnings of one of its core features: dissociation. As a transdiagnostic phenomenon, dissociation has been related to alterations in precuneus function and structure in other neuropsychiatric disorders as well as through electrical stimulation. Still, the role of the precuneus in dissociative seizures needs further investigation. Here, we use retrospectively gathered neuroimaging data from 88 patients with dissociative seizures and 79 neurologically healthy controls to relate measures of illness severity and dissociative symptoms to cortical thickness and volume of the precuneus. Clinical-grade MRI scans from multiple scanners were processed using the FreeSurfer 7.4.1 recon-all-clinical pipeline and adjusted for scanner-related variability with the ComBat algorithm. No between-group differences were found; but in patients with dissociative seizures, older age at illness onset was associated with lower left and right precuneus volumes. Additionally, before correcting for multiple testing, we observed negative correlations between left precuneus volume and longer duration of illness, and between precuneus thickness and dissociative symptoms, which can inform future hypotheses. In conclusion, this study investigating the role of the precuneus in dissociative seizures found potential evidence for correlations of precuneus structure with clinical illness features and dissociative symptoms, albeit interpretations should be cautious due to the loss of significance through correction for multiple testing and the retrospective, exploratory nature of the study.