Psychogenic seizures and frontal disconnection: EEG synchronisation study

Abstract

Objective Psychogenic non-epileptic seizures (PNES) are paroxysmal events that, in contrast to epileptic seizures, are related to psychological causes without the presence of epileptiform EEG changes. Recent models suggest a multifactorial basis for PNES. A potentially paramount, but currently poorly understood factor is the interplay between psychiatric features and a specific vulnerability of the brain leading to a clinical picture that resembles epilepsy. Hypothesising that functional cerebral network abnormalities may predispose to the clinical phenotype, the authors undertook a characterisation of the functional connectivity in PNES patients. Methods The authors analysed the whole-head surface topography of multivariate phase synchronisation (MPS) in interictal high-density EEG of 13 PNES patients as compared with 13 age-and sex-matched controls. MPS mapping reduces the wealth of dynamic data obtained from high-density EEG to easily readable synchronisation maps, which provide an unbiased overview of any changes in functional connectivity associated with distributed cortical abnormalities. The authors computed MPS maps for both Laplacian and common-averagereference EEGs.Results In a between-group comparison, only patchy, non-uniform changes in MPS survived conservative statistical testing. However, against the background of these unimpressive group results, the authors found widespread inverse correlations between individual PNES frequency and MPS within the prefrontal and parietal cortices. Interpretation PNES appears to be associated with decreased prefrontal and parietal synchronisation, possibly reflecting dysfunction of networks within these regions.

Frontal electroencephalographic (EEG) activity and mediumship: a comparative study between spiritist mediums and controls

“…Contrary to the pattern of decreased synchronization that has been described to occur in pathological dissociation 13 or during hypnosis 17 , in the present study, the analyses of clusters of electrodes revealed no between-group differences in frontal interhemispheric, left frontal-posterior or right frontal-posterior coherences whether in theta or in beta frequency range. In fact, in mediums' group, a nonsignificant increase in average frontal interhemispheric and left frontal-posterior coherence was noted, both in theta and in beta frequency range.…”

“…Replicating the few available prior EEG studies on this research field 18,19 , we observed that mediums had greater theta and beta power during the anomalous sensorial experience compared to non-medium controls. The lack of reduction in frontal interhemispheric and frontal-posterior coherence in mediums group during the alleged mediumistic communication clearly differs from the coherence pattern reported in pathological dissociation 13 and during the hypnotic state 17 . The EEG spectral power and connectivity data observed in this sample of experienced and mentally healthy mediums suggest that cognitive control processes seem to be engaged during the anomalous sensorial experiences.…”

“…A study investigating EEG coherence in individuals with psychogenic nonepileptic seizures (PNES), a dissociative disorder, found decreased fronto-parietal coherence in carriers compared to control participants. Moreover, they found an inverse correlation between the number of events and fronto-parietal coherence 13 .…”

Functional Neuroanatomy and Neurophysiology of Functional Neurological Disorders (Conversion Disorder)

“…Abnormalities in connectivity and neural networks in PNES have been investigated using EEG and resting state fMRI. Knyazeva et al 100 studied PNES (N=13) and healthy volunteers (N=13) using multivariate phase synchronization in interictal highdensity EEG and did not show any group differences; however, their results show decreased prefrontal and parietal synchronization with a greater number of PNES events. Barzegaran et al 101 further analyzed these results using graph theory, showing that patients with PNES had similar local and global connectivity and small-world structure, and the deficits in local connectivity correlated with the number of PNES per month.…”

Understanding psychogenic nonepileptic seizures—Phenomenology, semiology and the Integrative Cognitive Model

“…Reduced connectivity has also been shown to distinguish PNES patients from those with epilepsy with a high level of accuracy [37]. Although a study analysing whole-head surface topography of multivariate phase synchronisation in interictal high-density EEG failed to demonstrate any significant differences between 13 patients with PNES and the same number of age-and gender-matched controls, a significant correlation was found between decreased prefrontal and parietal synchronisation and PNES frequency in the patient group [38].…”