Volumetry of Cerebral cortex in psychogenic non-epileptic seizures: a VBM & cortical thickness study

2296 

Abstract Submission 

Farzaneh Dehghani¹, Alireza Aleali²

¹Research Center of Addiction and Behavioral Science, Shahid Sadoughi University of Medical Sciences, Yazd, Yazd, ²School of Allied Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Tehran

Farzaneh Dehghani  
Research Center of Addiction and Behavioral Science, Shahid Sadoughi University of Medical Sciences
Yazd, Yazd

Alireza Aleali  
School of Allied Medicine, Shahid Beheshti University of Medical Sciences
Tehran, Tehran

Psychogenic Non-Epileptic Seizures (PNES) are common functional neurological disorders resembling epileptic seizures but without abnormal neuronal activity. The mechanisms behind PNES are not well understood, with theories ranging from brain 'software defects' to alterations in specific brain regions. To address these inconsistencies and improve our understanding of PNES, our study employed Voxel Based Morphometry (VBM) and cortical thickness measurements in MRI scans. This approach was used to investigate structural differences in the brains of PNES patients compared to healthy controls, aiding in elucidating the pathophysiology of PNES.

Between November 2019 and September 2021, 21 patients with Psychogenic Non-Epileptic Seizures (PNES) were identified at Imam Khomeini Hospital, Tehran, Iran. Criteria included a history of seizure-like episodes and negative ictal EEG results. Exclusion criteria were the presence of epileptic seizures, significant medical, neurological, psychiatric conditions, substance abuse, or antipsychotic drug use. Additionally, 26 healthy individuals with no neurological or psychiatric history were included for comparison. Neurological examinations of all participants were normal. The study adhered to ethical standards, with informed consent obtained from all participants. Patients underwent neuropsychological and psychiatric evaluations, including the Addenbrooke's Cognitive Examination (ACE) and IQ assessments, indicating average IQ but some cognitive deficits. MRI scans were conducted using a Siemens 3.0-Tesla Prisma scanner. Parameters included T1-Weighted-MPRAGE with specific durations, angles, and resolutions detailed. SPM12 software was used for VBM analysis, involving normalization, segmentation, and smoothing of grey matter volume maps, followed by statistical analysis with ANCOVA, adjusting for intracranial volume, age, and gender. Freesurfer software was utilized for cortical thickness measurement. This included automated cortical reconstruction, manual correction of segmentation errors, and statistical analysis with significance values adjusted for multiple comparisons. Data normality was assessed using the Kolmogorov-Smirnov test. Group comparisons (PNES vs. healthy controls) were made using t-tests or Mann-Whitney U tests, with an alpha error value set at 0.05, using SPSS software.

Our study included 21 PNES patients (mean age 28.38±10.84 years, 16 females and 5 males) identified through video-EEG, with no exclusions. Brain MRIs showed no mass lesions. The mean age at first PNES episode was 14.65 years, with an average of 5.59 episodes per month. The control group consisted of 25 right-handed individuals (mean age 30.77±6.59 years, 13 females and 13 males), with no significant age or gender differences compared to the PNES group. Average ACE score was 89 (range 87-100), indicating normal cognitive function. IQ levels, assessed during interviews, were within normal limits, and neurological examinations were unremarkable. Significant gray matter loss in PNES patients was observed in various brain regions including the left occipital gyrus, lingual gyrus, right subcallosal gyrus, parahippocampal gyrus, and others, without adjusting for multiple comparisons. Conversely, there was an increase in gray matter in areas like the right premotor and supplementary motor area, superior frontal gyrus, and left precentral gyrus. No significant differences in cortical thickness were found between PNES patients and healthy controls.

In summary, our study comparing 21 PNES patients with 25 healthy controls found significant variations in gray matter volume in multiple brain regions of PNES patients, but no differences in cortical thickness. These findings suggest a neurobiological basis for PNES, indicating the need for further research to understand its underlying mechanisms and improve treatment approaches.

Education, History and Social Aspects of Brain Imaging

EEG/MEG Modeling and Analysis

Cortical Anatomy and Brain Mapping

Anatomical MRI ¹

EEG ²

Electroencephaolography (EEG)

Epilepsy

STRUCTURAL MRI

Sub-Cortical