The Etiology of Psychogenic Non-Epileptic Seizures: Toward a Biopsychosocial Model

Functional neurological disorder: Characteristics and outcome in a limited-resources country (Sudan)

BACKGROUND

There is a scarcity of reports from limited-resources countries on functional neurological disorder (FND). We therefore carried out this descriptive study from Sudan to highlight the clinical characteristics of patients and the cultural, diagnostic, and management outcome.

METHOD

Of 1000 new referrals and patients seen at a central neuropsychiatric clinic in Khartoum, Sudan, 40 fulfilled the criteria for FND. Subjects were diagnosed by excluding organic illness and confirming psychological distress through neuropsychological assessment and clinical interview. Mood was measured using the Beck Depression Inventory (BDI) and Hospital Anxiety and Depression (HAD) scales.

RESULTS

Young unemployed women constituted 60% of our sample. Most subjects presented with psychogenic nonepileptic seizures (82.5%), speech abnormalities (47.5%), and limb paralysis or weakness was (35%). Associated mood disorder was found in 97.5% of all subjects. However, 95% of our sample showed a remarkable clinical response to combination therapy (antidepressants and psychotherapy).

SIGNIFICANCE

Patients with FND showed strong evidence of comorbid affective disorders in the form of depression and anxiety disorder. Most patients (95%) responded well to combination therapy with antidepressants and psychotherapy. Sociodemographic correlates of FND in Sudan prove to be consistent with features found in Western cultures, with only minor idiosyncratic characteristics due to local culture.

An investigation into the preferred terminology for functional seizures

There is considerable debate in the literature regarding what to call functional seizures, with terms such as pseudoseizures, nonepileptic attack disorder (NEAD), and dissociative seizures being used. Provision of an accurate diagnosis and coherent explanation is a vital first step in the management of functional seizures and can result in cessation or reduced frequency for some individuals. This study investigated preferences for and offensiveness of terms used to describe functional seizures, and expectations for recovery with psychological treatment. A sample of 87 healthy adults completed an online survey, in which eight different diagnostic terms were ranked in order of preference (1 - most preferred, 8 - least preferred): functional nonepileptic attacks (FNEA), dissociative seizures, functional seizures, psychogenic seizures, NEAD, pseudoseizures, conversion disorder, and hysteria. Replicating Stone and colleagues protocol, each term was investigated for five connotations. Offense scores were calculated from the number of participants who selected 'yes' to at least one of the negative connotations ('Putting it on', 'Mad', and 'Imagining Symptoms'). Expectations about the possibility of recovering through medical or psychological treatment were also recorded. Functional nonepileptic attack was ranked the highest preferred term with dissociative seizures and functional seizures closely following. Nonepileptic attack disorder was the least offensive term, with FNEA and functional seizures joint second. Unsurprisingly, the three least preferred terms were also the most offensive: pseudoseizures, conversion disorder, and hysteria. Expectations of nonrecovery from psychological treatment were lowest for terms implicating a psychological cause: pseudoseizures, dissociative seizures, psychogenic seizures, and hysteria. The results suggest that either the terms FNEA or functional seizures should be adopted by healthcare professionals and patients, as they are the most preferred, least offensive, and expectations for nonrecovery with psychological treatment were moderate compared with the other terms. Limitations and areas for future research are discussed.

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.

The impact of sexual abuse on psychopathology of patients with psychogenic nonepileptic seizures

OBJECTIVES

In the present study, we evaluated if the presence of sexual abuse in the clinical history of patients with psychogenic non-epileptic seizures (PNES) is associated with a different psychopathological profile.

MATERIALS AND METHODS

In a consecutive population of 63 PNES patients, we compared two demographically and clinically matched groups of patients with (no. 15) and without (no. 48) a history of sexual abuse using a comprehensive psychopathological assessment (Beck Depression Inventory, Hamilton Anxiety Rating Scale, Dissociative Experience Scale, Somatoform Dissociation Questionnaire, and Toronto Alexithymia Scale).

RESULTS

We found that the group of patients reporting sexual abuse is characterized by higher scores on Dissociative Experience Scale (p = 0.003) and Beck Depression Inventory (p = 0.001) with respect to the other group. No significant statistical differences in Hamilton Anxiety Rating Scale (p = 0.103), Toronto Alexithymia Scale (p = 0.137), and Somatoform Dissociation Questionnaire (p = 0.486) were captured. Moreover, we found that the negative effect on dissociate symptoms was also hampered by the increasing of seizure frequency.

CONCLUSIONS

This study reinforces the importance of traumatic screening in the clinical spectrum of PNES in order to implement and improve specific therapeutic strategies.

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.

Management of functional neurological disorder

Functional neurological disorder (FND) is a common cause of persistent and disabling neurological symptoms. These symptoms are varied and include abnormal control of movement, episodes of altered awareness resembling epileptic seizures and abnormal sensation and are often comorbid with chronic pain, fatigue and cognitive symptoms. There is increasing evidence for the role of neurologists in both the assessment and management of FND. The aim of this review is to discuss strategies for the management of FND by focusing on the diagnostic discussion and general principles, as well as specific treatment strategies for various FND symptoms, highlighting the role of the neurologist and proposing a structure for an interdisciplinary FND service.

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.

International multicenter studies on psychogenic nonepileptic seizures: A systematic review

The aim of the current paper is to systematically review the literature on the existing international multicenter studies on various aspects of PNES and to highlight their findings and significance. I searched the electronic database PubMed for articles that included any of these search terms: Non-epileptic seizures, Nonepileptic seizures, Pseudoseizures, Non-epileptic events, Nonepileptic events, Dissociative seizures, Psychogenic, PNES, AND "international" or "multicenter" or "cross cultural", in their abstracts and titles and published before August 6, 2019. I searched PsycINFO database (keywords in the abstracts) and also included some of the references of the selected articles if they were relevant. I could identify 12 related manuscripts through the search strategy. These included seven studies on patients with PNES, two surveys, and three consensus group reports. This systematic review showed that international and cross-cultural studies on PNES to date are very limited in number and quality. However, these limited studies have resulted in intriguing observations and conclusions. International and cross-cultural studies may make important contributions to our understanding of different aspects of PNES across borders.

Clinical Classifications of Children With Psychogenic Non-epileptic Seizure

Objective: To analyze the clinical features of children with psychogenic non-epileptic seizures in one tertiary center in China. Methods: Clinical data including medical records and video- electroencephalograph (video-EEG) monitoring records of 88 pediatric PNES patients hospitalized in the pediatric department of Xuanwu Hospital, Beijing, China from April, 2012 to April, 2018 were collected in this study. Demographic information of patients, semiological classification, duration, and frequency of symptoms, risk factors as well as comorbidity were summarized and analyzed. Results: For semiological classification, all PNES related symptoms were divided into different categories: motor symptoms, unresponsiveness, sensory symptoms, visceral symptoms, and abnormal behaviors, among which motor symptoms were the most prevalent form. Risk factors were reviewed and categorized into two groups: persistent factors and predisposing factors, and patients were most frequently affected by the influences of families. The duration and frequency of symptoms varied substantially within PNES patients while the average time of duration was relatively longer than epilepsy as reported previously. Epilepsy was considered as the most frequent comorbidity of PNES and PNES patients misdiagnosed as epilepsy often mistreated with antiseizure medication. Significance: Our study showed that motor PNES are the most frequent seizure type. Family issues were a risk factor for PNES. Epilepsy was the most frequent co-existing neurological comorbidity.

First do no harm: Preventing harm and optimizing care in psychogenic nonepileptic seizures

Psychogenic nonepileptic seizures (PNES) are challenging clinical occurrences consisting of any combination of altered movement, sensation, or awareness that resemble epileptic seizures (ES) but do not coincide with electrographic ictal discharges and are presumed to be neuropsychiatric-neurobehavioral in origin. Securing the PNES diagnosis is a crucial first step and is best confirmed by recording events on video-electroencephalogram (v-EEG) and finding an absence of ictal EEG changes and the presence of normal awake EEG rhythms before, during, and after the event. However, obstacles to timely diagnosis and referral to psychiatric treatment frequently occur, placing these patients at risk for harm from unnecessary medications and procedure as well as placing high burden on medical systems. Although providers across all disciplines share the responsibility by maintaining high suspicion of PNES in relevant clinical settings and engaging swiftly and empathically in securing and sharing the diagnosis with patients and families, psychiatric and neurologic providers are uniquely positioned to help lead patients towards safe and effective long-term care through a cohesive approach that is rooted in therapeutic alliance, interdisciplinary collaboration, and realistic treatment goals.

Managing Functional Neurological Disorders: Protocol of a Cohort Study on Psychogenic Non-Epileptic Seizures Study

BACKGROUND

Functional neurological disorders (FNDs) are neurological symptoms that cannot be explained by an underlying neurological lesion or other medical illness and that do not have clear neuropathological correlates. Psychogenic non-epileptic seizures (PNES) are a common and highly disabling form of FND, characterized by paroxysmal episodes of involuntary movements and altered consciousness that can appear clinically similar to epileptic seizures. PNES are unique among FNDs in that they are diagnosed by video electroencephalographic (VEEG), a well-established biomarker for the disorder. The course of illness and response to treatment of PNES remain controversial. This study aims to describe the epidemiology of PNES in the Department of Veterans Affairs Healthcare System (VA), evaluate outcomes of veterans offered different treatments, and compare models of care for PNES.

METHODS

This electronic health record (EHR) cohort study utilizes an informatics search tool and a natural language processing algorithm to identify cases of PNES nationally. We will use VA inpatient, outpatient, pharmacy, and chart abstraction data across all 170 medical centers to identify cases in fiscal years 2002-2018. Outcome measurements such as seizure frequency, emergency room visits, hospital admissions, suicide-related behavior, and the utilization of psychotherapy prior to and after PNES diagnosis will be used to assess the effectiveness of models of care.

DISCUSSION

This study will describe the risk factors and course of treatment of a large cohort of people with PNES. Since PNES are cared for by a variety of different modalities, treatment orientations, and models of care, effectiveness outcomes such as seizure outcomes and utilization of emergency visits for seizures will be assessed. Outcome measurements such as seizure frequency, emergency room visits, hospital admissions, suicide-related behavior, and psychotherapy prior to and after PNES diagnosis will be used to assess the effectiveness of models of care.

Psychogenic nonepileptic seizures: The sex ratio trajectory across the lifespan

PURPOSE

We investigated the sex ratio trajectory across the lifespan in patients with psychogenic nonepileptic seizures (PNES). We hypothesized that there are significant changes in the trajectory of the sex ratio in these patients across the lifespan with respect to the age at onset.

METHODS

In this retrospective study, all patients with PNES, who were diagnosed at Shiraz Comprehensive Epilepsy Center, Iran, from 2008 until 2019, were investigated. We arbitrarily categorized the patients into five groups according to the age at onset of their PNES [pre-puberty (≤ 14 years), adolescence (15 years to < 19 years), young adulthood (19-25 years), adulthood (26-45 years), and post-menopausal (≥ 46 years)].

RESULTS

During the study period, 275 patients with PNES-only had the inclusion criteria. The sex ratios (female to male) of the studied groups according to the age at onset of PNES were as follows: pre-puberty (13:14 = 0.93), adolescence (32:21 = 1.52), young adulthood (54:33 = 1.64), adulthood (71:26 = 2.73), and post-menopausal (7:4 = 1.75). In two-by-two comparison of the group with the lowest sex ratio (pre-puberty) and the group with the highest sex ratio (adulthood) the difference was significant (p = 0.01).

CONCLUSION

We postulate that the higher prevalence of PNES in women may be partly associated with lifetime sex hormone fluctuations; this female preponderance appears during puberty and decreases after menopause. However, most likely this is only one of many potential reasons behind this sex difference; therefore, this is an interesting avenue for future studies.

Psychogenic nonepileptic seizures in pediatric population: A review

INTRODUCTION

Psychogenic nonepileptic seizures (PNES) are observable abrupt paroxysmal changes in behavior or consciousness that resemble epileptic seizures, but without concurrent electroencephalographic abnormalities.

METHODS

In this manuscript, we reviewed literature concerning pediatric PNES and focused on those articles published in the last 10 years, in order to try to understand what the state of the art is at the moment, particularly as regards relationship and differential diagnosis with epilepsy.

RESULTS

Psychogenic nonepileptic seizures have been extensively described in literature mainly in adults and less frequently in children. Despite the potential negative impact of a misdiagnosis (unnecessary investigations and antiepileptic drugs, structured pathological behavioral patterns), in literature there is little information regarding the real prevalence, clinical features, treatment, and outcome of PNES in children and adolescents.

CONCLUSION

Psychogenic nonepileptic seizures are common but frequently missed entity in pediatric population. Diagnosis could be difficult, especially in those children who have both epileptic and nonepileptic seizures; video EEG and home video can help clinicians in diagnosis. More studies are needed to better classify PNES in children and facilitate diagnosis and treatment.

Nonepileptic seizures in individuals attending neurological services in New Zealand

OBJECTIVES

This study examined the demographic, social, and clinical (neurological and psychiatric) characteristics of people with psychogenic nonepileptic seizures (PNES) presenting to tertiary neurological services at Auckland District Health Board, New Zealand.

METHODS

Electronic notes and video-electroencephalography (video-EEG) data gathered from the telemetry unit based on synchronized acquisition (motor activity and brain electrophysiology) over a five-year period (2011 to 2015 inclusive) were retrospectively examined. Two groups were compared: people with PNES only or people with combined PNES and epileptic seizures (ES) (the group with PNES) and a control group with ES only, matched 1:1 by age and gender.

RESULTS

Sixty-six people in the group with PNES were matched with an equivalent number of ES controls. As a cohort, there was high psychiatric and medical comorbidity in both groups, but overall, those with PNES experienced higher rates than their ES counterparts. An older age of onset, female gender, and history of abuse were more frequently seen in those with PNES. Compared with controls, people with PNES more commonly had daily seizures (rather than monthly) but presented less frequently to neurology services. A high proportion of people with PNES experienced historical traumas, ongoing stressors, and disability. Almost half of the people with PNES were on antiepileptic drugs (AEDs) and received limited psychiatric or psychological input. In contrast, people with ES were more likely to be on psychotropic medication.

CONCLUSION

Both PNES and ES are associated with high levels of psychiatric and medical comorbidity. Additionally, PNES were found to be associated with iatrogenic harm and disability. Though people with PNES and ES often have a range of associated needs, there is, however, limited access to appropriate services. The needs of these populations should be better met through enhanced integration across psychiatry, neurology, and multidisciplinary services.

Early communication is key - Designing a new communication tool to immediately empower people with psychogenic nonepileptic seizures

INTRODUCTION

Patient empowerment and shared decision-making has been increasingly recognized as key factors for a favorable prognosis. This is particularly true in complex brain disorders such as psychogenic nonepileptic seizures (PNES) which go along with several challenges. People with PNES (PW-PNES) often feel lost in the healthcare system. Early clear communication is one of the few favorable prognostic variables. Our goal was to design a new ultrashort user-friendly communication tool allowing immediate patient empowerment.

METHODS

We conceptualized a design thinking process with patient engagement of PW-PNES. Together with a larger group of PW-PNES, we developed a comprehensive user-friendly 1-page document summarizing the key features of PNES. We applied document engineering (DE) as a cognitive science-based new methodology. Document engineering is well established in the aviation, oil, and mining industries and measurably reduces comprehension and performance errors.

RESULTS

The design thinking process encompassed 5 phases (empathize, ideate, define, prototype, and test). A prototype of a 1-page document, the 1-Pager-PNES, was created which contained the essential 7 domains organized in a simple structure such as a promise-question-answer (PQA) format. Information was kept poignant, complete, easy-to-read integrating cognitive principles to optimize navigation. The prototype "1-Pager-PNES" was subsequently tested in a 7-member focus group. All patients expressed significant improvement in understanding their disease and felt immediately empowered. Implementing their specific feedbacks, reiterative testing, and involving PNES experts resulted in the final version of the "1-Pager-PNES".

CONCLUSION

A promising new communication tool reduced to 1-page only is introduced which improves patient guidance and enables better coping mechanisms with this complex disease. The patient/user is empowered quickly through finding answers to pressing questions. Our study is unique for three reasons: 1) it engaged patients in the developing process, 2) it produced a tool for immediate communication for PW-PNES, which follows principles of human behavior and cognitive science, and 3) it used cross-industry thinking. Despite all limitations, we consider our small pilot study an inspiration for future studies with focus on patient empowerment through user-friendly documents.

Memory and motor control in patients with psychogenic nonepileptic seizures

Psychogenic nonepileptic seizures (PNES) are of the most elusive phenomena in epileptology. Patients with PNES present episodes resembling epileptic seizures in their semiology yet lacking the underlying epileptic brain activity. These episodes are assumed to be related to psychological distress from past trauma, yet the underlying mechanism of this manifestation is still unknown. Using resting-state functional magnetic resonance imaging (fMRI), we investigated functional connectivity changes within and between large-scale brain networks in 9 patients with PNES, compared with a group of 13 age- and gender-matched healthy controls. Functional magnetic resonance imaging analyses identified functional connectivity disturbances between the medial temporal lobe (MTL) and the sensorimotor cortex and between the MTL and ventral attention networks in patients with PNES. Within network connectivity reduction was found within the visual network. Our findings suggest that PNES relate to changes in connectivity in between areas that are involved in memory processing and motor activity and attention control. These results may shed new light on the way by which traumatic memories may relate to PNES.

Patient and family perspectives of paediatric psychogenic non-epileptic seizures: A systematic review

Exploring the perspectives of those affected by psychogenic non-epileptic seizures (PNES) may be essential in learning more about the nature of this condition. The aim of this systematic review is to synthesise the evidence regarding the perspectives of children and adolescents with PNES, and the perspectives of their parents, caregivers and families. Studies were included if they (1) explored PNES in a paediatric population, (2) explored the perspectives of the child or adolescent with PNES, or the perspectives of their parents, caregivers or families, (3) were original research, and (4) were written in the English language. Eight studies were identified for inclusion following searching of CINAHL Complete, Medline (Ovid), PsycINFO, PubMed and Web of Science databases, along with additional hand searching of reference lists. Quality assessment of articles was conducted using the Critical Appraisal Skills Programme (CASP) qualitative checklist. Seven articles were deemed high quality, and one article was deemed moderate quality. Common threads across studies included: "legitimacy and the importance of understanding", "distress and the social and emotional impact of PNES" and "moving forward". Clinicians must take care in the delivery of the diagnosis; including the use of an appropriate name for this condition, and providing an explanation of PNES that is acceptable to the patient, as well as ensuring that follow-up support is provided. Further reviews are required that utilise more well-established quality appraisal scoring systems and with the inclusion of grey literature, which refers to evidence not published by commercial academic publishers.

Emotional processing in functional neurological disorder: a review, biopsychosocial model and research agenda

Functional neurological disorder (FND) is a common and highly disabling disorder, but its aetiology remains enigmatic. Conceptually, there has been reduced emphasis on the role of psychosocial stressors in recent years, with a corresponding increase in neurobiological explanations. However, a wealth of evidence supports the role of psychosocial adversities (eg, stressful life events, interpersonal difficulties) as important risk factors for FND. Therefore, there is a need to integrate psychosocial (environmental) and neurobiological factors (eg, sensorimotor and cognitive functions) in contemporary models of FND. Altered emotional processing may represent a key link between psychosocial risk factors and core features of FND. Here, we summarise and critically appraise experimental studies of emotional processing in FND using behavioural, psychophysiological and/or neuroimaging measures in conjunction with affective processing tasks. We propose that enhanced preconscious (implicit) processing of emotionally salient stimuli, associated with elevated limbic reactivity (eg, amygdala), may contribute to the initiation of basic affective/defensive responses via hypothalamic and brainstem pathways (eg, periaqueductal grey). In parallel, affect-related brain areas may simultaneously exert a disruptive influence on neurocircuits involved in voluntary motor control, awareness and emotional regulation (eg, sensorimotor, salience, central executive networks). Limbic-paralimbic disturbances in patients with FND may represent one of several neurobiological adaptations linked to early, severe and/or prolonged psychosocial adversity. This perspective integrates neurobiological and psychosocial factors in FND and proposes a research agenda, highlighting the need for replication of existing findings, multimodal sampling across emotional response domains and further examination of emotional influences on sensorimotor and cognitive functions in FND populations.

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.

Long-term outcome in a sample of underprivileged patients with psychogenic nonepileptic seizures (PNES) living in Argentina

OBJECTIVE

The objective of the present study was to perform a long-term follow-up of economically disadvantaged Latin American patients diagnosed as having psychogenic nonepileptic seizures (PNES) and contribute to the field's understanding of outcome in this population.

BACKGROUND

A handful of studies have examined outcome of patients once the diagnosis of PNES has been communicated. However, the vast majority of these have been conducted in the first world countries with samples that were predominantly Caucasian. There is limited knowledge about outcome in economically disadvantaged Latin American patients diagnosed as having PNES.

METHODS

This is a study of 23 patients (20 women, 3 men) with PNES in which demographic data (age, education, nationality, presence of psychological trauma, age of onset) were retrospectively retrieved from medical files. Follow-up was done through a telephonic questionnaire in which investigators collected clinical information (seizure characteristics at follow-up, and treatments employed) and changes in demographic data.

RESULTS

Patients from this Argentinian PNES sample demonstrated having many similar demographic and clinical characteristics to samples from US and European studies. Long-term follow-up revealed, however, decreased seizure frequency and intensity as well as a substantial improvement in occupational status. A majority had engaged in psychotherapy as well as alternative and complementary approaches. A majority had also developed what are suspected to be other functional symptoms.

CONCLUSIONS

Argentinian patients from economically disadvantaged backgrounds, diagnosed as having PNES reported improvements in seizure frequency and occupational status during long-term follow-up. Future studies will need to focus on what (e.g., communication of diagnosis, psychotherapy, alternative treatments) may have contributed to these changes.

Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?

Functional neurological (conversion) disorder (FND) is a condition at the interface of neurology and psychiatry. A "software" vs. "hardware" analogy describes abnormal neurobiological mechanisms occurring in the context of intact macroscopic brain structure. While useful for explanatory and treatment models, this framework may require more nuanced considerations in the context of quantitative structural neuroimaging findings in FND. Moreover, high co-occurrence of FND and somatic symptom disorders (SSD) as defined in DSM-IV (somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder; referred to as SSD for brevity in this article) raises the possibility of a partially overlapping pathophysiology. In this systematic review, we use a transdiagnostic approach to review and appraise the structural neuroimaging literature in FND and SSD. While larger sample size studies are needed for definitive characterization, this article highlights that individuals with FND and SSD may exhibit sensorimotor, prefrontal, striatal-thalamic, paralimbic, and limbic structural alterations. The structural neuroimaging literature is contextualized within the neurobiology of stress-related neuroplasticity, gender differences, psychiatric comorbidities, and the greater spectrum of functional somatic disorders. Future directions that could accelerate the characterization of the pathophysiology of FND and DSM-5 SSD are outlined, including "disease staging" discussions to contextualize subgroups with or without structural changes. Emerging neuroimaging evidence suggests that some individuals with FND and SSD may have a "software" and "hardware" problem, although if structural alterations are present the neural mechanisms of functional disorders remain distinct from lesional neurological conditions. Furthermore, it remains unclear whether structural alterations relate to predisposing vulnerabilities or consequences of the disorder.

A review of functional neurological symptom disorder etiology and the integrated etiological summary model

Functional neurological symptom disorder (FNSD) is characterized by neurological symptoms that are unexplained by other traditional neurological or medical conditions. Both physicians and patients have limited understanding of FNSD, which is often explained as a physical manifestation of psychological distress. Recently, diagnostic criteria have shifted from requiring a preceding stressor to relying on positive symptoms. Given this shift, we have provided a review of the etiology of FNSD. Predisposing factors include trauma or psychiatric symptoms, somatic symptoms, illness exposure, symptom monitoring and neurobiological factors. Neurobiological research has indicated that patients with FNSD have a decreased sense of agency and abnormal attentional focus on the affected area, both of which are modulated by beliefs and expectations about illness. Sick role and secondary gain may reinforce and maintain FNSD. The integrated etiological summary model combines research from various fields and other recent etiological models to represent the current understanding of FNSD etiology. It discusses a potential causal mechanism and informs future research and treatment.

Emotion dysregulation in patients with psychogenic nonepileptic seizures: A systematic review based on the extended process model

Psychogenic nonepileptic seizures (PNES) are characterized by paroxysmal alterations in motor and sensory functions resembling epileptic seizures, but are not caused by epileptiform activity. In recent years, there has been increasing scientific interest in emotion dysregulation in patients with PNES (pwPNES), but the literature has not yet been interpreted within a broader model of emotion dysregulation. The aim of this review was therefore to synthesize the existing literature on emotion dysregulation in pwPNES within the extended process model (EPM) of emotion regulation.

METHODS

PubMed and Web of Science were searched for studies relevant to emotion dysregulation as defined by the EPM. These studies were subjected to a bespoke quality appraisal tool. Studies of acceptable quality were categorized to the different stages of the EPM and critically appraised.

RESULTS

Studies of emotion regulation in pwPNES were generally of low quality - a finding largely driven by small sample sizes. However, there was evidence of emotion dysregulation characterized by deficits in the identification of patients' own emotional states, as well as the selection and implementation of maladaptive regulatory strategies, and altered exteroceptive emotional processing. However, heterogeneity in findings suggests that emotion dysregulation is likely linked to other psychological factors and not common to all pwPNES.

SIGNIFICANCE

This review suggests that while pwPNES are likely to experience emotion dysregulation as defined by the EPM, there is variability in the distribution of regulatory deficits in this patient population, and a person-centered approach should be taken when working with these patients. There is a need for more high quality and better-powered studies in this area.

Individual differences in corticolimbic structural profiles linked to insecure attachment and coping styles in motor functional neurological disorders

BACKGROUND

Insecure attachment and maladaptive coping are important predisposing vulnerabilities for Functional Neurological Disorders (FND)/Conversion Disorder, yet no prior structural neuroimaging studies have investigated biomarkers associated with these risk factors in FND populations. This magnetic resonance imaging study examined cortical thickness and subcortical volumes associated with self-reported attachment and coping styles in patients with FND. We hypothesized that insecure attachment and maladaptive coping would relate to limbic-paralimbic structural alterations.

METHODS

FreeSurfer cortical thickness and subcortical volumetric analyses were performed in 26 patients with motor FND (21 women; 5 men) and 27 healthy controls (22 women; 5 men). For between-group comparisons, patients with FND were stratified by Relationship Scales Questionnaire, Ways of Coping Scale-Revised, and Connor-Davidson Resilience Scale scores. Within-group analyses were also performed in patients with FND. All analyses were performed in the complete cohort and separately in women only to evaluate for gender-specific effects. Cortical thickness analyses were whole-brain corrected at the cluster-wise level; subcortical analyses were Bonferroni corrected.

RESULTS

In women with FND, dismissing attachment correlated with reduced left parahippocampal cortical thickness. Confrontive coping was associated with reduced right hippocampal volume, while accepting responsibility positively correlated with right precentral gyrus cortical thickness. These findings held adjusting for anti-depressant use. All FND-related findings were within the normal range when compared to healthy women.

CONCLUSION

These observations connect individual-differences in limbic-paralimbic and premotor structures to attachment and coping styles in FND. The relationship between parahippocampal thickness and dismissing attachment may indicate aberrant social-emotional and contextual appraisal in women with FND.

Occupational therapy for functional neurological disorders: a scoping review and agenda for research

Functional neurological disorders (FND)-also called psychogenic, nonorganic, conversion, and dissociative disorders-constitute one of the commonest problems in neurological practice. An occupational therapist (OT) is commonly involved in management, but there is no specific literature or guidance for these professionals. Classification now emphasizes the importance of positive diagnosis of FND based on physical signs, more than psychological features. Studies of mechanism have produced new clinical and neurobiological ways of thinking about these disorders. Evidence has emerged to support the use of physiotherapy and occupational therapy as part of a multidisciplinary team for functional movement disorders (FMD) and psychotherapy for dissociative (nonepileptic) attacks. The diagnosis and management of FND has entered a new evidence-based era and deserves a standard place in the OT neurological curriculum. We discuss specific management areas relevant to occupational therapy and propose a research agenda.

You've made the diagnosis of functional neurological disorder: now what?

Patients with functional neurological disorders (FND)/conversion disorder commonly present to outpatient clinics. FND is now a 'rule in' diagnosis based on neurological examination findings and semiological features. While neurologists may be more comfortable diagnosing patients with FND, there is only limited guidance as to how to conduct follow-up outpatient visits. Using clinical vignettes, we provide practical suggestions that may help guide clinical encounters including how to: (1) explore illness beliefs openly; (2) enquire longitudinally about predisposing vulnerabilities, acute precipitants and perpetuating factors that may be further elucidated over time; (3) facilitate psychotherapy engagement by actively listening for potentially unhelpful or maladaptive patterns of thoughts, behaviours, fears or psychosocial stressors that can be reflected back to the patient and (4) enquire about the fidelity of individual treatments and educate other providers who may be less familiar with FND. These suggestions, while important to individualise, provide a blueprint for follow-up FND clinical care.

Gender differences in prevalence of psychiatric disorders, levels of alexithymia, and coping strategies in patients with refractory mesial temporal epilepsy and comorbid psychogenic nonepileptic seizures

OBJECTIVE

The objective of this study was to investigate the psychological aspects and psychiatric disorders (PDs) in patients dually diagnosed with refractory temporal lobe epilepsy and mesial temporal sclerosis (TLE-MTS) with psychogenic nonepileptic seizures (PNES) treated in a tertiary center in order to find any gender differences in psychiatric, clinical, and sociodemographic characteristics.

METHOD

Psychiatric assessment was performed through the Diagnostic and Statistical Manual for Psychiatric Disorders - 5th edition (DSM-5). The Brazilian versions of the Medical Outcomes Study 36 (SF-36), Toronto Alexithymia Scale (TAS-20), Hamilton Depression Scale (HAM-D), Hamilton Anxiety Scale (HAM-A), and Ways of Coping Checklist (WCC) were applied.

RESULTS

Of the 47 patients enrolled (25 females; 53.2%), females were significantly more likely to have a history of previous psychiatric treatment (P=0.02), family history of epilepsy (P=0.01), and family history of PD (P=0.03). They also presented earlier onset of PNES (P=0.01) and higher PNES duration (P=0.02) compared with males. Major depressive disorder (MDD) was the most frequent PD (24; 51.0%). Females presented more psychiatric diagnoses (P<0.001), more diagnoses of MDD (P<0.001), and posttraumatic stress disorder (PTSD) (P<0.001). Several differences regarding quality of life, levels of alexithymia, anxiety/depressive symptoms, and coping strategies were observed between groups.

CONCLUSIONS

There are significant gender differences in psychiatric, clinical, and sociodemographic aspects in a group of patients with TLE-MTS and PNES, as well as in quality of life, levels of alexithymia, anxiety/depressive symptoms, and coping strategies. These gender differences suggest that specific approaches might be adopted depending on the patient's gender and, consequently, their distinct psychological/psychiatric profile.

Written Accounts of Living With Epilepsy or Psychogenic Nonepileptic Seizures: A Thematic Comparison

This study examines the subjective experience of living with epilepsy or psychogenic nonepileptic seizures (PNES) by thematically comparing individuals' written accounts of their condition. Five key differences emerged. Theme 1: "Seizure onset" revealed differences in how individuals think about and ruminate over the possible causes of their condition. Theme 2: "Emotive tone" demonstrated that writings of those with epilepsy reflected stable emotions (no intense emotional reactions), whereas those of writers with PNES reflected anxiety and low mood. Theme 3: "Seizure symptoms" showed differences in the conceptualization of seizures. Theme 4: "Treatment" explored differences in the diagnostic journey and experiences of health care professionals. Theme 5: "Daily life" revealed that those with epilepsy perceived sequelae and seizures as something that must be fought, whereas those with PNES tended to describe their seizures as a place they enter and something that has destroyed their lives. The findings have implications for treatment and management.

Resilience linked to personality dimensions, alexithymia and affective symptoms in motor functional neurological disorders

OBJECTIVE

Reduced resilience, a construct associated with maladaptive stress coping and a predisposing vulnerability for Functional Neurological Disorders (FND), has been under-studied compared to other neuropsychiatric factors in FND. This prospective case-control study investigated self-reported resilience in patients with FND compared to controls and examined relationships between resilience and affective symptoms, personality traits, alexithymia, health status and adverse life event burden.

METHODS

50 individuals with motor FND and 47 healthy controls participated. A univariate test followed by a logistic regression analysis investigated group-level differences in Connor-Davidson Resilience Scale (CD-RISC) scores. For within-group analyses performed separately in patients with FND and controls, univariate screening tests followed by multivariate linear regression analyses examined factors associated with self-reported resilience.

RESULTS

Adjusting for age, gender, education status, ethnicity and lifetime adverse event burden, patients with FND reported reduced resilience compared to controls. Within-group analyses in patients with FND showed that individual-differences in mental health, extraversion, conscientiousness, and openness positively correlated with CD-RISC scores; post-traumatic stress disorder symptom severity, depression, anxiety, alexithymia and neuroticism scores negatively correlated with CD-RISC scores. Extraversion independently predicted resilience scores in patients with FND. In control subjects, univariate associations were appreciated between CD-RISC scores and gender, personality traits, anxiety, alexithymia and physical health; conscientiousness independently predicted resilience in controls.

CONCLUSION

Patients with FND reported reduced resilience, and CD-RISC scores covaried with other important predisposing vulnerabilities for the development of FND. Future research should investigate if the CD-RISC is predictive of clinical outcomes in patients with FND.

The Inpatient Assessment and Management of Motor Functional Neurological Disorders: An Interdisciplinary Perspective

BACKGROUND

Motor functional neurologic disorders (FND)-previously termed "hysteria" and later "conversion disorder"-are exceedingly common and frequently encountered in the acute hospital setting. Despite their high prevalence, patients with motor FND can be challenging to diagnose accurately and manage effectively. To date, there is limited guidance on the inpatient approach to the neuropsychiatric evaluation of patients with functional (psychogenic) neurologic symptoms.

OBJECTIVE

The authors outline an inpatient multidisciplinary approach, involving neurology, psychiatry, and physical therapy, for the assessment and acute inpatient management of motor FND.

METHODS

A vignette of a patient with motor FND is presented followed by a discussion of general assessment principles. Thereafter, a detailed description of the neurologic and psychiatric assessments is outlined. Delivery of a "rule-in" diagnosis is emphasized and specific guidance for what can be accomplished postdiagnosis in the hospital is suggested.

DISCUSSION

We encourage an interdisciplinary approach beginning at the early stages of the diagnostic assessment once an individual is suspected of having motor FND.

CONCLUSIONS

Practical suggestions for the inpatient assessment of motor FND are presented. It is also important to individualize the diagnostic assessment. Future research should be conducted to test best practices for motor FND management in the acute inpatient hospital setting.

Psychogenic non-epileptic seizures: aetiology, diagnosis and management

Psychogenic non-epileptic seizures (PNES) have a significant impact on most patients in terms of distress, disability, loss of income and iatrogenic harm. Three-quarters of patients with PNES are initially misdiagnosed and treated for epilepsy. Misdiagnosis exposes patients to multiple iatrogenic harms and prevents them from accessing psychological treatment. In most cases, the patient's history (and witness accounts) should alert clinicians to the likely diagnosis of PNES. Since this diagnosis may be resisted by patients and may involve ‘un-diagnosing’ epilepsy, video-electroencephalogram recording of typical seizures is often helpful. The underlying causes of PNES are diverse: a model combining predisposing, precipitating and perpetuating factors is a useful way of conceptualising their aetiology. The initial step of treatment should be to limit iatrogenic harm. There is some evidence for the effectiveness of psychotherapy.

A simple clinical score for prediction of nonepileptic seizures

Psychogenic nonepileptic seizures (PNES), often mistaken for epilepsy in community practice, require inpatient video-EEG (VEEG) monitoring for diagnostic confirmation. We developed a simple score designed for use in an outpatient setting to predict the subsequent VEEG diagnosis of PNES. We retrospectively compared fifty-five consecutive patients with VEEG-proven PNES (N₁=55) with a group of randomly selected patients with VEEG-proven epilepsy (N₂=55). Patients were divided into two groups: I) a 'truly retrospective' group of 27 patients with PNES and 27 patients with epilepsy whose data served to develop the score, and II) a 'pseudoprospective' group of 28 patients each with PNES and epilepsy to whom the score was applied. Six features in the history of the Group I cohort appeared more prominent in patients with PNES than patients with epilepsy and were assigned escalating numerical values as follows: number of declared drug allergies (0, 0.5, 1), number of declared comorbidities (0, 0.5, 1), number of previous invasive medical interventions of any type (0, 0.5, 1), and a history of significant psychological or physical trauma (0 or 1). In addition, a score was assigned to verbal description of the seizures themselves as being consistent (=0), atypical (=1), or indeterminate (=0.5) for epilepsy. The values were added to yield an omnibus score ranging from 0 to 6. Scoring of Group II subjects in a blinded fashion revealed that in general patients with PNES had higher scores, and the majority obtained a score >2; most patients with epilepsy scored <1.5. Group difference in the mean between the PNES and epilepsy cohort was highly significant (p<0.0001, Wilcoxon rank-sum test). Our score is a simple clinical instrument based on the patient history that may find use in the triage of patients awaiting hospitalization for VEEG and in pre-VEEG counseling.

Differentiating PNES from epileptic seizures using conversational analysis

We applied conversation analysis in an unselected continuous series of 70 patients to discriminate patients with psychogenic nonepileptic seizures (PNES) from patients with epilepsy. Two psychologists examined the patients' recorded reports. Patients were also submitted to an extensive neuropsychological battery in order to verify whether specific cognitive deficits or mental health problems are typical of patients with PNES and whether some cognitive deficits could prevent the correct diagnosis. The results showed a good percentage of correct diagnosis, with a sensitivity of 0.795 and a specificity of 0.83, while no difference in the cognitive profile was found between patients with PNES and patients with epilepsy. The results also suggest that psychologists can apply the conversation analysis as well as linguists, which is an important finding since psychologists are employed in specialized centers, while linguists in general are not part of the team.

The psychological nature of seizure conditions

Background/Aims:

Epilepsy is a long-term health condition that is associated with multiple biological, psychological and behavioural factors. Psychogenic or non-epileptic conditions have caused much debate and controversy among clinicians and researchers. This paper outlines comprehensive assessments with the aim of describing the psychological nature of different types of seizure conditions.

Methods:

The retrospective study reports on a range of self-report psychometric data of 26 patients with epileptic, non-epileptic, or both types of seizure conditions. The Hospital and Anxiety and Depression Scale, the Dissociative Experiences Scale and the Emotional Processing Scale were used to assess psychological functioning and emotional distress. The Quality of Life in Epilepsy Inventory and the MOS Short-Form Health Survey 36 were administered to evaluate subjective experiences related to quality of life and disability.

Results:

Epileptic and non-epileptic seizures are formulated in the background of biopsychosocial stress theories. The questionnaire outcomes revealed complex profiles. All patient groups reported reduced quality of life. Differential patterns of psychological distress were discovered for both diagnostic groups.

Conclusion:

The findings from this heterogeneous clinical population suggest that patients with epileptic and non-epileptic conditions demonstrate secondary psychological and functional difficulties. Future systematic research is required to establish valid measures of long-term psychosocial strain and to provide evidence for the link between maladaptive physiological mechanisms and psychological problems (and vice versa).

Simultaneous occurrence of nonepileptic and epileptic seizures during a single period of in-patient video-electroencephalographic monitoring

Epilepsy and psychogenic nonepileptic seizures (PNES) can coexist and may present in two forms: sequential and simultaneous. In sequential presentations, epileptic seizures (ES) are treated and PNES emerge later. Simultaneous recording of ES and PNES by video‐electroencephalogram (vEEG) is less well described. We retrospectively reviewed all patients diagnosed with PNES by vEEG following standard seizure induction practices over a 21‐month period. Within this cohort, we established the prevalence of coexisting epilepsy using clinical and electrographic data acquired from our epilepsy‐specific patient record. We identified patients with simultaneous PNES and ES recorded during a single vEEG admission, establishing the frequency and emergent timing of each type. Of our 262 monitored patients, 59 were diagnosed with PNES. Nineteen of the patients with PNES had coexisting epilepsy (prevalence rate of 7.3% or 32% of those with PNES). Sixteen patients had PNES and ES recorded during the same admission, and the remaining three patients had sequential PNES following successful treatment of ES. PNES occurred earlier (mean, within 1.21 days), with ES occurring later (mean, within 4.86 days). The simultaneous occurrence of PNES and ES recorded during a single admission is more common than previously reported. Identifying this group of patients may require a significantly longer period of vEEG monitoring and a detailed analysis of each individual's historical seizure events.

Treating functional non-epileptic attacks - Should we consider acceptance and commitment therapy?

Patients who experience functional non-epileptic attacks (FNEA) are frequently seen in Neurology clinics. Diagnosis alone can result in cessation of attacks for some patients, but many patients require further treatment. There is evidence that certain psychological therapies, like cognitive-behavioral therapy (CBT) and psychodynamic interpersonal therapy (PIT) can be beneficial. Acceptance and commitment therapy (ACT) is a type of CBT that has been found to be effective at treating other somatic disorders, like epilepsy and chronic pain. In this paper, we explain what ACT is, the current evidence-base for its use, and the rationale for why it may be a beneficial treatment for patients who experience FNEA. We conclude that ACT is a potential treatment option for FNEA, and further research is required.

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.