Neurobiological origin of psychogenic nonepileptic seizures: A review of imaging studies

Psychogenic nonepileptic seizures: Are they a freeze reaction?

Psychogenic nonepileptic seizures (PNES) clinically resemble epileptic seizures (ES) but lack epileptic activity at the time of the seizure and are also not due to any other pathophysiological disorder. The integrative cognitive model (ICM) suggests that PNES is an automatic reaction generated from distorted memory and is perceived as uncontrollable and unwanted. Furthermore, the ICM model implies that a PNES event occurs due to an external or internal cue. Intrigued by this assumption, we wanted to examine why a PNES event occurs at a particular moment by investigating the pre-ictal behavior. This study is a retrospective study. We included all patients diagnosed with PNES or ES admitted to our long-term video-EEG monitoring unit (LTVEM) between 01/01/2018 and 30/08/2020. Using thorough video analysis, we checked the patient's state at the onset of the event and looked back to see what the patient was doing before the event onset. We defined 4 types of pre-ictal behavior A. Inactivity. B. Environment arrangement c. Other. D. No apparent pre-ictal behavior. Thirty patients with PNES and 30 patients with ES were included in the study. In total, 46 PNES events and 56 ES events were recorded and analyzed. In 33 /46 PNES seizures (72%), a type A, A + B or C pre-ictal behavior was observed compared to 1/56 ES (1.78%) with type A pre-ictal behavior. All other pre-ictal behavior in the ES group were of type D. Patients with PNES have a unique pre-ictal behavior before most PNES events with motor manifestations. Since the pre-ictal behavior consists mainly of inactivity, we believe it may imply that PNES represents a freeze reaction or a reconstruction of a freeze reaction.

Dissoziative Anfälle frühzeitig erkennen

Wenn dissoziative Anfälle, also psychogene, nichtepileptische Anfälle als epileptische Anfälle fehlgedeutet werden, führt dies zu frustraner medikamentöser Therapie und verzögert die Einleitung der erforderlichen psychotherapeutischen Maßnahmen. Folgende Anfallssymptome sollten an dissoziative Anfälle denken lassen: unrhythmisches, wildes Hin- und Herbewegen des Kopfes oder der Extremitäten, geschlossene Augen, lange Dauer und undulierender Verlauf. Ein unauffälliges Elektroenzephalogramm (EEG) spricht für dissoziative Anfälle, aber erst ein negativer EEG-Befund während eines Anfalls ist beweisend. Im Arztgespräch ist es entscheidend, dass die Betroffenen die Möglichkeit bekommen, frei zu schildern. Betroffene mit dissoziativen Anfällen zeigen dann Besonderheiten, die als Diagnosekriterien genutzt werden sollten: Sie fokussieren auf Begleitumstände und lassen in ihren Schilderungen den Moment des Bewusstseinsverlusts aus. Sie machen eher allgemeine Angaben und unterscheiden einzelne Anfälle kaum.

Effective connectivity between emotional and motor brain regions in people with psychogenic nonepileptic seizures (PNES)

OBJECTIVE

To characterize the effective connectivity (EC) between the emotion and motor brain regions in patients with psychogenic nonepileptic seizures (PNES), based on resting-state spectral dynamic causal modeling (spDCM).

METHODS

Twenty-three patients with PNES and twenty-five healthy control (HC) subjects underwent resting-state fMRI scanning. The coupling parameters indicating the causal interactions between eight brain regions associated with emotion, executive control, and motion were estimated for both groups, using resting-state fMRI spDCM.

RESULTS

Compared to the HC subjects, in patients with PNES: (i) the left insula (INS) and left and right inferior frontal gyri (IFG) are more inhibited by the amygdala (AMYG), anterior cingulate cortex (ACC), and precentral gyrus (PCG); (ii) the left AMYG has greater inhibitory effects on the INS, IFG, dorsolateral prefrontal cortex (DLPFC), PCG, and supplementary motor area (SMA); (iii) the left ACC has more inhibitory effects on the INS and IFG; (iv) the right ACC is more inhibited by the INS and IFG, and has a less inhibitory effect on the SMA and PCG; and (v) the left caudate (CAU) had increased inhibitory effects on the AMYG and IFG and a more excitatory effect on the SMA.

CONCLUSION

Our results suggest that in patients with PNES, the emotion-processing regions have inhibitory effects on the executive control areas and motor regions. Our findings may provide further insight into the influence of emotional arousal on functional movements and the underlying mechanisms of involuntary movements during functional seizures. Furthermore, they may suggest that emotion regulation through cognitive behavioral psychotherapies can be a potentially effective treatment modality.

Orbito-frontal thinning together with a somatoform dissociation might be the fingerprint of PNES

OBJECTIVE

To investigate neuroanatomical changes in patients with psychogenic nonepileptic seizures (PNES) compared to major depressive disorder (MDD) and healthy controls.

METHODS

Forty-two drug-naïve PNES subjects and 25 patients with MDD, matched for demographic characteristics and level of depression (as measured by Beck Depression Inventory-II, BDI-II), were consecutively recruited. Patients performed an extensive neuropsychiatric assessment including: Hamilton Anxiety Rating Scale, Traumatic Experience Checklist, Dissociative Experiences Scale, Toronto Alexithymia Scale and Somatoform Dissociation Questionnaire (SDQ-20). All patients, together with 78 healthy matched controls, underwent 3T brain MRI followed by surface-based morphometry.

RESULTS

Cortical thickness analysis revealed significant cortical thinning in bilateral medial orbitofrontal cortex (OFC) and left rostral anterior cingulate cortex (ACC) in patients with MDD compared to subjects with PNES and controls. Interestingly, increased thickness of the right pars triangularis was found in PNES subjects compared to controls. PNES showed higher scores in SDQ-20 (p < 0.001) compared to MDD, which was corroborated by neuroimaging data, where somatoform dissociation scores correlated with morphological changes in the left medial OFC.

CONCLUSION

Our results show selective cortical thinning over the medial OFC in patients with PNES compared to wider regions of thinning in patients with MDD. Somatoform dissociation was the only psychopathological assessment significantly different in PNES and MDD.

A minority of patients with functional seizures have abnormalities on neuroimaging

OBJECTIVE

Functional seizures often are managed incorrectly as a diagnosis of exclusion. However, a significant minority of patients with functional seizures may have abnormalities on neuroimaging that typically are associated with epilepsy, leading to diagnostic confusion. We evaluated the rate of epilepsy-associated findings on MRI, FDG-PET, and CT in patients with functional seizures.

METHODS

We studied radiologists' reports from neuroimages at our comprehensive epilepsy center from a consecutive series of patients diagnosed with functional seizures without comorbid epilepsy from 2006 to 2019. We summarized the MRI, FDG-PET, and CT results as follows: within normal limits, incidental findings, unrelated findings, non-specific abnormalities, post-operative study, epilepsy risk factors (ERF), borderline epilepsy-associated findings (EAF), and definitive EAF.

RESULTS

Of the 256 MRIs, 23% demonstrated ERF (5%), borderline EAF (8%), or definitive EAF (10%). The most common EAF was hippocampal sclerosis, with the majority of borderline EAF comprising hippocampal atrophy without T2 hyperintensity or vice versa. Of the 87 FDG-PETs, 26% demonstrated borderline EAF (17%) or definitive EAF (8%). Epilepsy-associated findings primarily included focal hypometabolism, especially of the temporal lobes, with borderline findings including subtle or questionable hypometabolism. Of the 51 CTs, only 2% had definitive EAF.

SIGNIFICANCE

This large case series provides further evidence that, while uncommon, EAF are seen in patients with functional seizures. A significant portion of these abnormal findings are borderline. The moderately high rate of these abnormalities may represent framing bias from the indication of the study being "seizures," the relative subtlety of EAF, or effects of antiseizure medications.

Is sexual trauma a risk factor for functional (psychogenic) seizures?

The relationship between functional seizures (FS) and sexual trauma has received attention in many previous studies. However, the mechanisms underlying this relationship have not been elucidated yet. The purpose of this narrative review is to explore and speculate on the underpinning neurobiological mechanisms for the association and link between sexual trauma and functional seizures. While existence of a causal relationship between a history of sexual trauma and functional seizures is plausible, it should be viewed and treated as a hypothesis. In explaining this hypothesis, we can speculate that interactions between genetic factors and a history of sexual trauma may contribute to the risk of experiencing functional seizures. Childhood sexual trauma may lead to structural and functional connectivity changes in the brain and dysregulation of the biological stress systems, particularly in women. These neurobiological changes speculatively may predispose patients to functional seizures later in life. Importantly, a history of sexual trauma has many other implications beyond the predisposition towards FS.

Neuroimaging-based brain-age prediction in diverse forms of epilepsy: a signature of psychosis and beyond

Epilepsy is a diverse brain disorder, and the pathophysiology of its various forms and comorbidities is largely unknown. A recent machine learning method enables us to estimate an individual's "brain-age" from MRI; this brain-age prediction is expected as a novel individual biomarker of neuropsychiatric disorders. The aims of this study were to estimate the brain-age for various categories of epilepsy and to evaluate clinical discrimination by brain-age for (1) the effect of psychosis on temporal lobe epilepsy (TLE), (2) psychogenic nonepileptic seizures (PNESs) from MRI-negative epilepsies, and (3) progressive myoclonic epilepsy (PME) from juvenile myoclonic epilepsy (JME). In total, 1196 T1-weighted MRI scans from healthy controls (HCs) were used to build a brain-age prediction model with support vector regression. Using the model, we calculated the brain-predicted age difference (brain-PAD: predicted age-chronological age) of the HCs and 318 patients with epilepsy. We compared the brain-PAD values based on the research questions. As a result, all categories of patients except for extra-temporal lobe focal epilepsy showed a significant increase in brain-PAD. TLE with hippocampal sclerosis presented a significantly higher brain-PAD than several other categories. The mean brain-PAD in TLE with inter-ictal psychosis was 10.9 years, which was significantly higher than TLE without psychosis (5.3 years). PNES showed a comparable mean brain-PAD (10.6 years) to that of epilepsy patients. PME had a higher brain-PAD than JME (22.0 vs. 9.3 years). In conclusion, neuroimaging-based brain-age prediction can provide novel insight into or clinical usefulness for the diverse symptoms of epilepsy.

Brain functional connectivity in individuals with psychogenic nonepileptic seizures (PNES): An application of graph theory

OBJECTIVE

To determine brain functional connectivity (FC), based on the graph theory, in individuals with psychogenic nonepileptic seizures (PNES), in order to better understand the mechanisms underlying this disease.

METHODS

Twenty-three patients with PNES and twenty-five healthy control subjects were examined. Alterations in FC within the whole brain were examined using resting-state functional magnetic resonance imaging (MRI). We calculated measures of the nodal degree, a major feature of the graph theory, for all the cortical and subcortical regions in the brain. Pearson correlation was performed to determine the relationship between nodal degree in abnormal brain regions and patient characteristics.

RESULTS

The nodal degrees in the right caudate (CAU), left orbital part of the left inferior frontal gyrus (ORBinf), and right paracentral lobule (PCL) were significantly greater (i.e. hyper-connectivity) in individuals with PNES than in healthy control subjects. On the other hand, a lesser nodal degree (i.e. hypo-connectivity) was detected in several other brain regions including the left and right insula (INS), as well as the right putamen (PUT), and right middle occipital gyrus (MOG).

CONCLUSION

Our findings suggest that the FC of several major brain regions can be altered in individuals with PNES. Areas with hypo-connectivity may be involved in emotion processing (e.g., INS) and movement regulation (e.g., PUT), whereas areas with hyper-connectivity may play a role in the inhibition of unwanted movements and cognitive processes (e.g., CAU).

Social aspects of life in patients with functional (psychogenic nonepileptic) seizures: An international study

PURPOSE

To explore various social aspects of life (i.e., employment, education, and driving) in a large sample of patients with functional seizures (FS) living in seven countries from four continents.

METHODS

In this retrospective study, we investigated adult patients with FS, who were admitted to the epilepsy monitoring units at centers in Iran, Qatar, USA, France, Georgia, Egypt, and United Arab Emirates (UAE). We studied the social aspects of life in the whole cohort. Then, we compared the social aspects of life between different world regions.

RESULTS

Four hundred and forty patients were included (241 from Iran, 56 from Qatar, 52 from France, 41 from the USA, 19 from UAE, 18 from Egypt, and 13 from Georgia). One hundred and twenty six people (30%) had college education, 142 (33%) were employed, and 101 (28%) drove a motor vehicle in their routine daily lives. People with FS and college education were more likely to report a history of sexual abuse compared with those with a lower education. Patients with no loss of responsiveness with their FS were more likely to be employed. Male patients and patients without aura were more likely to drive a motor vehicle in their routine daily lives. None of the social characteristics of the patients with FS showed significant differences among the two large culturally different groups (Muslim nations vs. Christian nations).

CONCLUSION

It appears that patients with FS across cultures have significant problems in their social aspects of life.

Neurochemicals of limbic system and thalamofrontal cortical network: Are they different between patients with idiopathic generalized epilepsy and psychogenic nonepileptic seizure?

OBJECTIVE

Thalamofrontal cortical network and limbic system are proposed to be involved in psychogenic nonepileptic seizure (PNES) and idiopathic generalized epilepsy (IGE). This study aimed to investigate neurochemical changes in prefrontal cortex, thalamus, and limbic circuits in patients with PNES and IGE. We also analyzed the interaction between cognitive functions and neurochemical changes in both groups.

METHODS

Hydrogen proton magnetic resonance spectroscopy (1H-MRS) was used to measure N-acetyl aspartate (NAA), choline (Cho), creatine (Cr), glutamate-glutamine (Glx), and myo-inositol (MI). The voxels were placed on the bilateral dorsolateral prefrontal cortex (DLPFC), dorsomedial prefrontal cortex (DMPFC), anterior cingulate cortex (ACC), and thalamus. Attention and inhibitory control, as well as general intelligence status, were investigated using the Integrated Visual and Auditory Continuous Performance Test (IVA-CPT) and the Wechsler Adult Intelligence Scale (WAIS), respectively, in patients with PNES and IGE, as well as healthy volunteers.

RESULTS

The 1H-MRS showed a decreased ratio of NAA/Cr in the right and left thalamus, right DMPFC, and right ACC in patients with IGE and PNES. Furthermore, a decrease of the NAA/Cr ratio in the left DMPFC and an increase of NAA/Cr ratio in the right DLPFC were observed in patients with PNES compared with the controls. The patient groups had a decreased ratio of Cho/Cr in right ACC compared with the healthy subjects. Moreover, the NAA/Cr ratio in the left thalamus and left DMPFC was correlated with seizure frequency in patient groups. Reduced NAA/Cr ratio in the right ACC and left DLPFC were also correlated with poor IVA-CPT scores.

CONCLUSION

This study highlighted the dysfunction in prefrontal-thalamic-limbic circuits and impairment in neurocognition in patients with PNES and IGE.

Unexpected brain imaging findings in patients with seizures

New imaging technologies have advanced our ability to localize the epileptogenic zone in patients with epilepsy. As a result of the constant improvement of the image quality, magnetic resonance imaging (MRI) has become the most important ancillary tool in the management of patients with epilepsy. Magnetic resonance imaging for the evaluation of patients with epilepsy should be done using a special temporal lobe protocol and read by physicians experienced with the findings in patients with epilepsy. On the other hand, in the healthy populations, incidental structural brain abnormalities have been reported in 18% of people. Incidental, subtle, or unexpected structural brain abnormalities have also been reported in many patients who were investigated because of having seizures. In the current narrative review, we will discuss some of these instances, where structural brain abnormalities are discovered unexpectedly, are subtle (but important) and/or may be considered as incidental.

Brain connectivity abnormalities in patients with functional (psychogenic nonepileptic) seizures: A systematic review

OBJECTIVES

The aim of the current endeavor was to systematically review the existing evidence on brain connectivity abnormalities in patients with functional seizures (FS).

METHODS

This systematic review was prepared according to the instructions of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. MEDLINE (accessed from PubMed) and Scopus from inception to April 4, 2020 were systematically searched. The following search strategy was implemented and these key words (in the title/abstract) were used: "connectivity" OR "network" AND "psychogenic" OR "dissociative" OR "nonepileptic".

RESULTS

Through the search strategy, we could identify eighteen articles. These studies have applied various methodologies and they could identify a variety of brain connectivity abnormalities in people with FS. However, none of these studies provided a high level of evidence. They were all small studies (none had a sample size of more than 21 patients). In addition, most of the studies did not match their cases and their controls with respect to the psychiatric comorbidities and other significant confounders.

CONCLUSION

Abnormal functional connectivity between emotion processing areas of the brain with regions involved in executive control and cognitive performance, and the functional connections of the anterior cingulate cortex are of major interest and may be involved in the pathophysiology of FS. Pursuing the concept of brain connectivity abnormalities in patients with FS and comparing the findings with well-matched controls in well-designed studies may result in a breakthrough in identifying the exact neurobiological origin of FS.

Psychogenic nonepileptic (functional) seizures: Significance of family history and model learning

PURPOSE

If a positive family history of seizures plays a significant role that contributes to the risk for developing psychogenic nonepileptic seizures (PNES) by means of model learning, one would expect that patients with PNES with a family history of seizures show a different semiology than those without such a history. We investigated whether the above hypothesis is valid.

METHODS

In this retrospective study, all patients with PNES, who were diagnosed at Shiraz Comprehensive Epilepsy Center at Shiraz University of Medical Sciences, Iran, from 2008 until 2019, were investigated. Demographic and clinical characteristics were compared between patients with a positive family history of seizures and those without such a history RESULTS: During the study period, 274 patients with PNES-only had the inclusion criteria. Seventy-seven (28%) patients had a positive family history of seizures and 197 (72%) patients did not have such a history. There were no significant demographic or clinical differences between the two groups.

CONCLUSION

It seems that a positive family history of seizures and model learning does not play a significant role in the development of PNES. Investigators should explore other potentially significant contributors and risk factors for developing PNES in future studies.

Psychogenic Non-epileptic Seizures and Pseudo-Refractory Epilepsy, a Management Challenge

Psychogenic nonepileptic seizures (PNES) are neurobehavioral conditions positioned in a gray zone, not infrequently a no-man land, that lies in the intersection between Neurology and Psychiatry. According to the DSM 5, PNES are a subgroup of conversion disorders (CD), while the ICD 10 classifies PNES as dissociative disorders. The incidence of PNES is estimated to be in the range of 1.4-4.9/100,000/year, and the prevalence range is between 2 and 33 per 100,000. The International League Against Epilepsy (ILAE) has identified PNES as one of the 10 most critical neuropsychiatric conditions associated with epilepsy. Comorbidity between epilepsy and PNES, a condition leading to "dual diagnosis," is a serious diagnostic and therapeutic challenge for clinicians. The lack of prompt identification of PNES in epileptic patients can lead to potentially harmful increases in the dosage of anti-seizure drugs (ASD) as well as erroneous diagnoses of refractory epilepsy. Hence, pseudo-refractory epilepsy is the other critical side of the PNES coin as one out of four to five patients admitted to video-EEG monitoring units with a diagnosis of pharmaco-resistant epilepsy is later found to suffer from non-epileptic events. The majority of these events are of psychogenic origin. Thus, the diagnostic differentiation between pseudo and true refractory epilepsy is essential to prevent actions that lead to unnecessary treatments and ASD-related side effects as well as produce a negative impact on the patient's quality of life. In this article, we review and discuss recent evidence related to the neurobiology of PNES. We also provide an overview of the classifications and diagnostic steps that are employed in PNES management and dwell on the concept of pseudo-resistant epilepsy.

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.

Terminology for psychogenic nonepileptic seizures: Making the case for "functional seizures"

PURPOSE

The purpose of the study was to review the literature on the terminologies for psychogenic nonepileptic seizures (PNES) and make a proposal on the terminology of this condition. This proposal reflects the authors' own opinions.

METHODS

We systematically searched MEDLINE (accessed from PubMed) and EMBASE from inception to October 10, 2019 for articles written in English with a main focus on PNES (with or without discussion of other functional neurological disorders) and which either proposed or discussed the accuracy or appropriateness of PNES terminologies.

RESULTS

The search strategy reported above yielded 757 articles; 30 articles were eventually included, which were generally of low quality. "Functional seizures" (FS) appeared to be an acceptable terminology to name this condition from the perspective of patients. In addition, FS is a term that is relatively popular with clinicians.

CONCLUSION

From the available evidence, FS meets more of the criteria proposed for an acceptable label than other popular terms in the field. While the term FS is neutral with regard to etiology and pathology (particularly regarding whether psychological or not), other terms such as "dissociative", "conversion", or "psychogenic" seizures are not. In addition, FS can potentially facilitate multidisciplinary (physical and psychological) management more than other terms. Adopting a universally accepted terminology to describe this disorder could standardize our approach to the illness and facilitate communication between healthcare professionals, patients, their families, carers, and the wider public.

Adult-onset psychogenic nonepileptic seizures: A multicenter international study

PURPOSE

The aim of this multicenter international cross-cultural study was to compare clinical variables in a large sample of people with adult-onset psychogenic nonepileptic seizures (PNES).

METHODS

In this retrospective study, we evaluated persons with documented PNES, who were older than 16 years of age at the onset, from four countries (i.e., Iran, Brazil, Venezuela, and Argentina) regarding their age, gender, PNES semiology, and possible predisposing factors.

RESULTS

We included 389 patients (244 from Iran, 66 from Brazil, 51 from Venezuela, and 28 from Argentina). Age at diagnosis was 32 ± 9 years (range: 17-64 years), and age at the onset of seizures was 27 ± 8 years (range: 17-49 years). There was a female predominance in all countries. The demographic characteristics and factors associated with PNES were similar among the countries. However, there were significant semiological differences among the countries.

CONCLUSION

This study corroborates the notion that PNES share more similarities than differences cross-culturally and across international borders. However, the background determined by cultural, ethnic, and religious differences may influence the semiology of PNES. Further cross-cultural studies involving more than two continents may advance our understanding of PNES.

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.

Sex differences in demographic and clinical characteristics of psychogenic nonepileptic seizures: A retrospective multicenter international study

PURPOSE

Sex-related differences have been reported in patients with neurological and psychiatric disorders. It is also plausible to assume that there might be differences between females and males with psychogenic nonepileptic seizures (PNES).

METHODS

In this retrospective study, we investigated patients with PNES, who were admitted to the epilepsy monitoring units at centers in Iran, the USA, Canada, Brazil, Argentina, and Venezuela. Age, sex, age at seizure onset, seizure semiology, factors potentially predisposing to PNES, and video-electroencephalography recording of all patients were registered routinely.

RESULTS

Four hundred and fifty-one patients had PNES-only and were eligible for inclusion; 305 patients (67.6%) were females. We executed a logistic regression analysis, evaluating significant variables in univariate analyses (i.e., age, age at onset, aura, presence of historical sexual or physical abuse, and family dysfunction). The only variables retaining significance were historical sexual abuse (p = 0.005) and presence of aura (p = 0.01); physical abuse was borderline significant (p = 0.05) (all three were more prevalent among females).

CONCLUSION

Similarities between females and males outweigh the differences with regard to the demographic and clinical characteristics of PNES. However, notable differences are that females more often report lifetime adverse experiences (sexual and probably physical abuse) and auras. While social, psychological, and genetic factors may interact with lifetime adverse experiences in the inception of PNES, the link is not yet clear. This is an interesting avenue for future studies.

Psychogenic nonepileptic seizures in children and adolescents: An international cross-cultural study

PURPOSE

We compared various clinical characteristics of psychogenic nonepileptic seizures (PNES) between young patients from Iran, Saudi Arabia, and Canada, three nations with significantly different socioeconomic and demographic characteristics. This international cross-cultural comparative study may advance our knowledge and understanding of PNES in children and adolescents across the cultures and borders.

METHODS

In this retrospective study, we investigated all patients 16 years of age or younger, with PNES admitted to the epilepsy monitoring units at one center in Iran, one center in Saudi Arabia, and one center in Canada. Age, gender, age at seizure onset, seizure semiology, seizure frequency, factors potentially predisposing to PNES, and video-electroencephalography (EEG) recording of all patients were registered routinely and compared between the nations.

RESULTS

Fifty-one patients were studied (22 from Iran, 14 from Saudi Arabia, and 15 from Canada). Age at the diagnosis was 13.4 ± 2.2 years (range: 8-16 years), and age at the onset of seizures was 12.3 ± 2.7 years (range: 5-16 years). Demographic and clinical characteristics of and associated factors in the patients among the three nations were not significantly different. Twenty-six (51%) patients were taking antiepileptic drugs at the time of diagnosis; the difference was not statistically significant between the nations (13 patients in Iran, 6 in Saudi Arabia, and 7 patients in Canada; P = 0.5).

CONCLUSION

Young patients with PNES across borders and between cultures share more similarities than differences with regard to their demographic and clinical characteristics.

Widely Impaired White Matter Integrity and Altered Structural Brain Networks in Psychogenic Non-Epileptic Seizures

OBJECTIVE

The underlying neural correlates of psychogenic non-epileptic seizures (PNES) are still unknown and their identification would be helpful for clinicians and patients. This study aimed to reveal details of white matter microstructure and alterations in brain structural networks in patients with PNES by using diffusion tensor imaging (DTI) and graph theoretical connectivity analysis.

METHODS

Seventeen patients with PNES and 26 age- and sex-matched healthy controls were enrolled. All participants underwent DTI on a 3.0-T MRI scanner, and fractional anisotropy (FA) and mean diffusivity (MD) maps were compared by tract-based spatial statistics. Additionally, the structural networks derived from DTI data were analyzed using graph theory and two different parcellation schemes.

RESULTS

Patients with PNES showed widespread decreases in FA and increases in MD, particularly in the deep white matter. In addition, graph theoretical analysis revealed impaired brain networks in PNES, including increased path length, decreased network efficiency, altered nodal topology, and reduced regional connectivity in the right posterior areas.

CONCLUSION

We found widely impaired white matter integrity and impaired brain structural networks in Japanese patients with PNES. These findings contribute to the accumulation of evidence on PNES and may improve understanding of this condition.

The application of artificial intelligence to understand the pathophysiological basis of psychogenic nonepileptic seizures

Psychogenic nonepileptic seizures (PNES) are episodes of paroxysmal impairment associated with a range of motor, sensory, and mental manifestations, which perfectly mimic epileptic seizures. Several patterns of neural abnormalities have been described without identifying a definite neurobiological substrate. In this multicenter cross-sectional study, we applied a multivariate classification algorithm on morphological brain imaging metrics to extract reliable biomarkers useful to distinguish patients from controls at an individual level. Twenty-three patients with PNES and 21 demographically matched healthy controls (HC) underwent an extensive neuropsychiatric/neuropsychological and neuroimaging assessment. One hundred and fifty morphological brain metrics were used for training a random forest (RF) machine-learning (ML) algorithm. A typical complex psychopathological construct was observed in PNES. Similarly, univariate neuroimaging analysis revealed widespread neuroanatomical changes affecting patients with PNES. Machine-learning approach, after feature selection, was able to perform an individual classification of PNES from controls with a mean accuracy of 74.5%, revealing that brain regions influencing classification accuracy were mainly localized within the limbic (posterior cingulate and insula) and motor inhibition systems (the right inferior frontal cortex (IFC)). This study provides Class II evidence that the considerable clinical and neurobiological heterogeneity observed in individuals with PNES might be overcome by ML algorithms trained on surface-based magnetic resonance imaging (MRI) data.

Neuroimaging studies in patients with psychogenic non-epileptic seizures: A systematic meta-review

Psychogenic Non-epileptic Seizures (PNES) are ‘medically unexplained’ seizure-like episodes which superficially resemble epileptic seizures but which are not caused by epileptiform discharges in the brain. While many experts see PNES disorder as a multifactorial biopsychosocial condition, little is known about the neurobiological processes which may predispose, precipitate and/or perpetuate PNES symptomology. This systematic meta-review advances our knowledge and understanding of the neurobiological correlates of PNES by providing an up-to-date assessment of neuroimaging studies performed on individuals with PNES. Although the results presented appear inconclusive, they are consistent with an association between structural and functional brain abnormalities and PNES. These findings have implications for the way in which we think about this “medically unexplained” disorder and how we communicate the diagnosis to patients. However, it is also evident that neuroimaging studies in this area suffer from a number of significant limitations and future larger studies will need to better address these if we are to improve our understanding of the neurobiological correlates of predisposition to and/or manifestation of PNES.

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Neuroimaging results point to neurobiological correlates of PNES.

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Lack of convergent findings point to heterogeneous condition.

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Lack of high quality neuroimaging studies represents weak evidence base.

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Larger serial neuroimaging studies to assess state/trait characteristics required

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Future neuroimaging studies should use additional objective physiological measures.

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.

Semiological classification of psychogenic nonepileptic seizures

PURPOSE

We classified patients with psychogenic nonepileptic seizures (PNESs) according to a newly proposed classification system. Then, we investigated the demographic and clinical differences between various classes of the patients.

METHODS

We retrospectively investigated all patients with PNESs admitted to the Jefferson Comprehensive Epilepsy Center from 2012 through 2016. We classified the patients into four distinct classes: patients with generalized motor seizures, patients with akinetic seizures, patients with focal motor seizures, and patients with seizures with subjective symptoms. All patients were interviewed by a neuropsychologist and were administered psychological assessment measures, including questions about PNES risk factors. For the statistical analyses, we compared patients who had generalized motor seizures with patients who had nonmotor seizures.

RESULTS

Sixty-three patients were studied. Thirty-five (55.6%) patients had generalized motor seizures, 14 (22.2%) had seizures with subjective symptoms, 12 (19%) had akinetic seizures, and two (3.2%) patients had focal motor seizures. Patients with generalized motor seizures (35 patients) demonstrated a trend for later age at onset (p=0.06), more frequently had a history of substance abuse (p=0.001), and more often had loss of responsiveness with their seizures (p=0.04) compared with patients who had nonmotor seizures (26 patients).

CONCLUSION

The recently proposed PNES classification system is useful and practical. This proposed classification of PNESs may address proper diagnosis and provide standardization across future studies. This may also potentially shed light on the etiologic understanding and management of various classes of patients affected with PNESs.

Biological underpinnings of psychogenic nonepileptic seizures: directions for future research

Psychogenic nonepileptic seizures (PNES) are relatively common occurrences in epilepsy centers, but their pathophysiology is still poorly understood. Research that elucidates the pathophysiology of PNES, including their neurobiological basis and biomarkers, may have important clinical implications. The literature provides some evidence that genetic factors, intrinsic factors, and environmental factors probably play a significant role as the biological underpinnings of PNES. Researchers may be able to learn more about the pathophysiology of PNES by investigating the effects of each of these factors on functional and structural brain connectivity.