Transient cortico‐cortical disconnection during psychogenic nonepileptic seizures (PNES)

Abstract

Psychogenic nonepileptic seizures (PNES) are paroxysmal clinical events that are often misdiagnosed as epileptic seizures, but which are not associated with electrographic discharge. Brain connectivity changes occurring during PNES are not known. We studied functional connectivity (Fc) in two patients with drug-resistant epilepsy, explored by stereotactic electroencephalography (EEG), in whom we recorded both epileptic seizures (ES) and PNES. Functional connectivity using pair-wise nonlinear correlation was computed between signals from seven brain areas: amygdala, hippocampus, lateral temporal cortex, anterior insula, orbitofrontal cortex, prefrontal cortex, and lateral parietal cortex. We assessed changes in global Fc during PNES in comparison with a background period. During PNES, a global decrease of Fc occurred between the different brain regions studied, compared with the interictal period. In both patients, decreased Fc was prominent in connections involving the anterior insula and parietal cortex. In conclusion, some PNES are associated with ictal functional disconnection between brain areas, particularly involving the parietal cortices and the anterior insula.

Mean Dynamics Index: a useful tool to identify motor psychogenic non epileptic seizures

“…Other previous studies supported the insular cortex's role in the conscious representation of self [44], interception, and emotions [45]. the researchers hypothesized that this "disconnection" might serve as a protective mechanism to avoid representations that would be considered threatening [36].…”

“…Altered consciousness is present in many PNES and may result from a process of dissociation [35]). An SEEG study that recorded two patients' PNES events demonstrated a global decrease of Frontal connectivity, particularly prominent in connections involving the anterior insula and parietal cortex [36].…”

“…The researchers interpreted these findings as a functional disconnection, resulting from alterations in long-distance Fc involving the parietal cortex, and a disconnection of the anterior insula (AI), that cause lack of normal continuous production of predictions, thus contributing to a feeling of being "disconnected" [36].…”

How to do things with words: Two seminars on the naming of functional (psychogenic, non-epileptic, dissociative, conversion, …) seizures

“…As introduced by Aileen McGonigal, an epileptologist, in her pre-seminar video, the alterations of function culminating in PNES can be understood as occurring at the level of neurophysiology, [14][15][16] but at present psychological models are relatively more developed. 17,18 While most participants in both seminars eschewed the mind-body dualism that has held these different levels of explanation to be fundamentally different in kind, a number of arguments were made emphasising one or the other.…”

Case Report: Atonic PNES Capture in fMRI

“…Because PNES are unpredictable and transient, two types of studies investigating the PNES physiopathology were performed: ictal (during the seizure) and interictal studies (between seizures). Regarding ictal studies, one work has shown a decreased functional connectivity between the anterior insula, hippocampus, amygdala, parietal, and prefrontal cortices during PNES ( 5 ). This work used a stereo-electroencephalography in two patients with epilepsy, which is a technology providing high temporal resolution but a low spatial sampling.…”