Biological underpinnings of psychogenic nonepileptic seizures: directions for future research

Differentiation of epilepsy and psychogenic nonepileptic events based on body fluid characteristics

OBJECTIVE

Differential diagnosis between epileptic seizures and psychogenic nonepileptic events (PNEEs) is a worldwide problem for neurologists. The present study aims to identify important characteristics from body fluid tests and develop diagnostic models based on them.

METHODS

This is a register-based observational study in patients with a diagnosis of epilepsy or PNEEs at West China Hospital of Sichuan University. Data from body fluid tests between 2009 and 2019 were used as a training set. We constructed models with a random forest approach in eight training subsets divided by sex and categories of tests, including electrolyte, blood cell, metabolism, and urine tests. Then, we collected data prospectively from patients between 2020 and 2022 to validate our models and calculated the relative importance of characteristics in robust models. Selected characteristics were finally analyzed with multiple logistic regression to establish nomograms.

RESULTS

A total of 388 patients, including 218 with epilepsy and 170 with PNEEs, were studied. The AUROCs of random forest models of electrolyte and urine tests in the validation phase achieved 80.0% and 79.0%, respectively. Carbon dioxide combining power, anion gap, potassium, calcium, and chlorine in electrolyte tests and specific gravity, pH, and conductivity in urine tests were selected for the logistic regression analysis. C (ROC) of the electrolyte and urine diagnostic nomograms achieved 0.79 and 0.85, respectively.

SIGNIFICANCE

The application of routine indicators of serum and urine may help in the more accurate identification of epileptic and PNEEs.

The neurobiology of functional neurological disorders characterised by impaired awareness

We review the neurobiology of Functional Neurological Disorders (FND), i.e., neurological disorders not explained by currently identifiable histopathological processes, in order to focus on those characterised by impaired awareness (functionally impaired awareness disorders, FIAD), and especially, on the paradigmatic case of Resignation Syndrome (RS). We thus provide an improved more integrated theory of FIAD, able to guide both research priorities and the diagnostic formulation of FIAD. We systematically address the diverse spectrum of clinical presentations of FND with impaired awareness, and offer a new framework for understanding FIAD. We find that unraveling the historical development of neurobiological theory of FIAD is of paramount importance for its current understanding. Then, we integrate contemporary clinical material in order to contextualise the neurobiology of FIAD within social, cultural, and psychological perspectives. We thus review neuro-computational insights in FND in general, to arrive at a more coherent account of FIAD. FIAD may be based on maladaptive predictive coding, shaped by stress, attention, uncertainty, and, ultimately, neurally encoded beliefs and their updates. We also critically appraise arguments in support of and against such Bayesian models. Finally, we discuss implications of our theoretical account and provide pointers towards an improved clinical diagnostic formulation of FIAD. We suggest directions for future research towards a more unified theory on which future interventions and management strategies could be based, as effective treatments and clinical trial evidence remain limited.

Structural Changes in Brain Magnetic Resonance Imaging Associated With Psychogenic Non-epileptic Seizures: An Analytical Cross-Sectional Study

Background Psychogenic non-epileptic seizures (PNES) are often seen as indicators of poor motor and sensory function caused by psychological responses to stressful experiences. A seizure might trigger these reactions. The aim of our study was to assess the structural changes in brain MRI associated with psychogenic non-epileptic seizures. Methodology A retrospective analytical cross-sectional study at the Department of Medicine and Neurology, Ayub Teaching Hospital, Abbottabad, was conducted from October 2020 to September 2021. The medical records of patients with confirmed PNES were collected and retrospectively evaluated. Results Medical records and MRI scans were accessible for 52 patients with PNES; 10 patients were excluded from the study. The average age of the patients (standard deviation) was 34 (±9) years, and the average age at onset was 31.6 (±5.8) years. Based on the video-EEG recordings, 57.1% of patients (n=24) were classified as having broadly generalized motor seizures, 40% of patients (n=17) were classified as having predominantly akinetic seizures defined primarily by blank spells, and only one patient was classified as having focal motor seizures. Only three patients (7%) had a positive epilepsy family history. Twenty-four (47.6%) patients with brain MRI scans reported abnormal findings, while 22 (52.4%) had normal MRI findings. The majority of patients with abnormal MRIs had nonspecific white matter changes (50%), mesial temporal sclerosis (15%), and cysts (15%). In a statistical analysis, age at the beginning of PNES (p = 0.04), duration of PNES (p=0.01), concomitant epilepsy (p = 0.05), generalized motor seizures (p= 0.03), and focal motor seizures (p= 0.02) were strongly associated with abnormal brain MRI findings. Conclusion Research reveals that persons with PNES have a higher-than-average prevalence of anatomical brain abnormalities. The main takeaway is that these findings lend credence to the growing body of data suggesting that PNES may not be a medical mystery but rather a disorder with physical foundations in the brain. Important implications for diagnosing and treating PNES patients are discussed, as are the outcomes of earlier neuroimaging investigations of PNES. Studying the involvement of structural brain anomalies in the etiology of psychogenic non-epileptic seizures requires further well-designed multicenter studies with larger sample sizes and a consistent imaging approach (PNES). It is crucial to consider any confounding variables, such as co-occurring mental diseases, while designing this study.

Neurological disorder-associated genetic variants in individuals with psychogenic nonepileptic seizures

Psychogenic nonepileptic seizures (PNES) are diagnosed in approximately 30% of patients referred to tertiary care epilepsy centers. Little is known about the molecular pathology of PNES, much less about possible underlying genetic factors. We generated whole-exome sequencing and whole-genome genotyping data to identify rare, pathogenic (P) or likely pathogenic (LP) variants in 102 individuals with PNES and 448 individuals with focal (FE) or generalized (GE) epilepsy. Variants were classified for all individuals based on the ACMG-AMP 2015 guidelines. For research purposes only, we considered genes associated with neurological or psychiatric disorders as candidate genes for PNES. We observe in this first genetic investigation of PNES that six (5.88%) individuals with PNES without coexistent epilepsy carry P/LP variants (deletions at 10q11.22-q11.23, 10q23.1-q23.2, distal 16p11.2, and 17p13.3, and nonsynonymous variants in NSD1 and GABRA5). Notably, the burden of P/LP variants among the individuals with PNES was similar and not significantly different to the burden observed in the individuals with FE (3.05%) or GE (1.82%) (PNES vs. FE vs. GE (3 × 2 χ2), P = 0.30; PNES vs. epilepsy (2 × 2 χ2), P = 0.14). The presence of variants in genes associated with monogenic forms of neurological and psychiatric disorders in individuals with PNES shows that genetic factors are likely to play a role in PNES or its comorbidities in a subset of individuals. Future large-scale genetic research studies are needed to further corroborate these interesting findings in PNES.

Medical comorbidities in patients with psychogenic non-epileptic seizures (functional seizures)

PURPOSE

We investigated medical comorbidities in patients with psychogenic non-epileptic seizures (PNES). We hypothesized that these patients commonly have significant medical comorbidities.

METHODS

In this retrospective study, all patients with PNES, who were diagnosed at Shiraz Comprehensive Epilepsy Center, Iran, from 2008 until 2019, were investigated. Age, gender, age at seizure onset, seizure semiology, and characteristics, known medical (organic) comorbidities reported by the patients and video-electroencephalography recordings of all patients were registered routinely.

RESULTS

During the study period, 272 patients with PNES-only had the inclusion criteria and were studied. Sixty-five patients (24%) reported having a medical (organic) comorbidity. The most commonly reported medical comorbidity was thyroid disorder. Age at onset (OR: 1.058; 95% CI: 1.026-1.090; p = 0.0001), duration of disease before the diagnosis (OR: 1.071; 95% CI: 1.025-1.119; p = 0.002), and sex (female) (OR: 1.97; 95% CI: 1.016-3.834; p = 0.04) were significantly associated with having medical comorbidities.

CONCLUSION

While we did not have a control group to provide the number and type of medical problems that are expected in the general population, and therefore our results should be interpreted with caution, we had some intriguing observations. About one quarter of patients with PNES reported having medical comorbidities. The exact nature of the relationship between medical illnesses and PNES is not clear; however, hypothetically they could have a complex relationship. This study provides valuable information on the frequency and nature of medical comorbidities in patients with PNES and opens new horizons for future research.

Psychogenic nonepileptic seizures publications in PubMed: Geographical distribution of the publications

PURPOSE

The aim of the current study was to depict a comprehensive geographical picture of the existing literature on psychogenic nonepileptic seizures (PNES) and to highlight the needs for future works.

METHODS

We searched the electronic database PubMed on June 8, 2019 for articles that included any of the related key words to analyze all the relevant literature. We applied the advance search; field was adjusted to the title and dates were adjusted to 01/01/2000 until 06/08/2019. We selected the relevant articles. Location of the study was determined according to the affiliation(s) of the authors.

RESULTS

1017 papers were included. Interest in research and publication on PNES has risen over the past two decades. Six hundred and nine full length research original papers and 199 review articles were published on PubMed from 2000 until 2019. Continent-wise, most articles were from North America and Europe (41.1% of the whole publications from Europe and 40.8% from North America; 833 papers totally), followed by Asia (92 papers), Oceania (36 papers) and South America (31 publications), while only 0.9% of the papers (9 papers) were from Africa.

CONCLUSION

A global campaign is necessary to inform and educate the world on the issue of PNES and its significance. While PNES merit further epidemiological investigations, there is a significant disparity with regard to the location of the studies. There is a huge need to invest more on studies on various aspects of PNES in many places in the world, including African nations, India, and China.

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.

Parental consanguinity in patients with psychogenic nonepileptic seizures

PURPOSE

The aim of this study was to investigate the rate of consanguinity of parents of the patients with psychogenic nonepileptic seizures (PNES). This would provide important information for future studies on the potential genetic bases of PNES.

METHODS

In this retrospective study, all patients with PNES, who were studied at Shiraz Comprehensive Epilepsy Center at Shiraz University of Medical Sciences, from 2008 to 2018, were recruited. We categorized the patients as (1) no consanguineous marriage of the parents and (2) with consanguineous marriage of the parents.

RESULTS

Three-hundred and sixteen patients had the data on their parental consanguinity available and were studied. The sex ratio (female:male) of the patients was 1.92 (208:108). Parents of 110 (35%) patients had consanguineous marriage, and parents of 206 (65%) patients did not. Demographic variables, seizure-related variables, PNES-associated factors, and the use of antiepileptic drugs were not significantly associated with parental consanguinity in the patients.

CONCLUSIONS

In this study, we observed that more than one-third of the patients with PNES had parental consanguinity. This rate is very similar to the rate of consanguinity in the general population in Iran.

Psychogenic nonepileptic seizures: a concise review

Psychogenic nonepileptic seizures (PNES) are commonly diagnosed and treated at epilepsy centers; however, their neurobiology is still poorly understood. Diagnosis relies on a multidisciplinary evaluation and is usually based on different combinations of data. They are diagnosed most reliably by recording a seizure while under video-EEG monitoring. Treatment includes multiple phases. Fewer than 40% of adults with PNES are expected to become seizure-free within 5 years after diagnosis. This article presents a concise review of the current literature about the definition, diagnosis, epidemiology, clinical characteristics, treatment, and prognosis of PNES.