Internal gating and somatization disorders: proposing a yet un-described neural system

Preliminary Evidence for Limbic-Frontal Hyperexcitability in Psychogenic Nonepileptic Seizure Patients

OBJECTIVES

The goal of the current pilot project was to probe the resting-state magnetoencephalography (MEG) in individuals with psychogenic nonepileptic seizures (PNES) and ascertain if there is evidence for frontal temporal cortical hyperexcitability, as evidenced by increased focal coherence in these regions.

METHODS

Six patients with PNES and without any evidence of epilepsy were included. Nine healthy control (HC) subjects (age matched as a group) were also included. Subjects underwent 10 minutes of eyes open and 10 minutes of eyes closed MEG recording without any specific cognitive tasks (ie, resting state).

RESULTS

Analysis shows posterior-occipital alpha power to be decreased but fronto-temporal delta/theta power increased in people with PNES compared with HC subjects. Analyses of mean interregional functional connectivity of 54 brain regions, patients with PNES tended to have reduced mean coherence in extra-fronto-temporal regions (ex-FTRs) while increased mean coherence in fronto-temporal regions (FTRs) compared with HC. Furthermore, all 6 patients with PNES had their highest coherence structure within the FTRs. This is in contrast to the HC subjects where only 3 of the 9 subjects had their highest coherence value structure in the FTRs (χ² = 6.67, P = .010).

CONCLUSIONS

The above findings are consistent with a disbalance between frontotemporal and posterior brain regions in this population with possible increased excitability in the FTRs. The data support the need for further investigations of the pathophysiology of PNES. The identification of a biomarker for PNES would not only provide for more informed therapeutic approaches, but it could also eliminate the stigma associated with the diagnosis of PNES.