Orbito-frontal thinning together with a somatoform dissociation might be the fingerprint of PNES

Objective: To investigate neuroanatomical changes in patients with psychogenic non-epileptic seizures (PNES) compared to major depressive disorder (MDD). Methods: Forty-two drug-naïve PNES patients and 25 MDD, matched for demographic, cognitive and level of depression (as measured by Beck Depression Inventory-II, BDI-II), were consecutively recruited. Patients performed a wide neuropsychiatric assessment, including: Hamilton Anxiety Rating Scale (HAM-A), Traumatic Experience Checklist (TEC), Dissociative Experiences Scale (DES), Toronto Alexithymia Scale (TAS-20) and Somatoform Dissociation Questionnaire (SDQ-20). All patients, together with 78 healthy matched controls, underwent a brain 3T MRI followed by surface-based morphometry. Results: Cortical thickness analysis revealed significant bilateral cortical thinning in the medial orbitofrontal cortex (OFC) and left rostral anterior cingulate cortex (ACC) in patients with MDD compared to patients with PNES and controls. PNES patients showed higher scores in SDQ-20 (p <0.001) with respect to the MDD group and this clinical evidence was corroborated by neuroimaging data, where somatoform dissociation scores correlated with morphological changes in the left medial OFC. Conclusion: Our results show selective cortical thinning over the medial OFC in patients with PNES compared to wider neurodegenerative cortex in patients with MDD. Somatoform dissociation was the only psychopathological assessment able to discriminate PNES from MDD in the context of atrophic OFC.