Neuroanatomic correlates of psychogenic nonepileptic seizures: a cortical thickness and VBM study

Psychogenic nonepileptic seizures (PNES) are among the most common clinical manifestations of conversion disorder and consist of paroxysmal behavior that resembles epileptic seizures. Preliminary data from functional neuroimaging studies gave plausible evidence that limbic circuits and sensorimotor cortex might be engaged in conversion disorder. Nonetheless, no advanced magnetic resonance imaging (MRI) studies have focused on patients with PNES.

We enrolled 20 consecutive patients in whom the diagnosis of PNES was based on ictal video-electroencephalography (EEG) of the habitual episodes and 40 healthy subjects matched for age and sex All patients underwent a formal neuropsychological investigation and a neuropsychiatric assessment. All of the patients also underwent two distinct morphologic whole-brain MR measurements, voxel-based morphometry (VBM), and cortical thickness analysis, in a multimethod approach.

None of the patients had serious medical or neurologic illness, substance abuse, or psychotic disorder, or were taking antipsychotic drugs. VBM and cortical thickness analyses in the patients with PNES revealed abnormal cortical atrophy of the motor and premotor regions in the right hemisphere and the cerebellum bilaterally. We also observed a significant association between increasing depression scores and atrophy involving the premotor regions.

The results of this study illustrate that motor and premotor regions in the right hemisphere and the cerebellum bilaterally play an important role in the pathogenesis of PNES and that these structures are correlated with depressive symptoms. Our findings suggest a multistep model in the pathogenesis of PNES, in which the phenomenology is driven by psychological factors interacting with specific biologic abnormalities.