Contributions of fMRI towards our understanding of the response to psychosocial stress in epilepsy and psychogenic nonepileptic seizures

Parvalbumin neurons in the nucleus accumbens shell modulate seizure in temporal lobe epilepsy

A growing number of clinical and animal studies suggest that the nucleus accumbens (NAc), especially the shell, is involved in the pathogenesis of temporal lobe epilepsy (TLE). However, the role of parvalbumin (PV) GABAergic neurons in the NAc shell involved in TLE is still unclear. In this study, we induced a spontaneous TLE model by intrahippocampal administration of kainic acid (KA), which generally induce acute seizures in first 2 h (acute phase) and then lead to spontaneous recurrent seizures after two months (chronic phase). We found that chemogenetic activation of NAc shell PV neurons could alleviate TLE seizures by reducing the number and period of focal seizures (FSs) and secondary generalized seizures (sGSs), while selective inhibition of PV exacerbated seizure activity. Ruby-virus mapping results identified that the hippocampus (ventral and dorsal) is one of the projection targets of NAc shell PV neurons. Chemogenetic activation of the NAc-Hip PV projection fibers can mitigate seizures while inhibition has no effect on seizure ictogenesis. In summary, our findings reveal that PV neurons in the NAc shell could modulate the seizures in TLE via a long-range NAc-Hip circuit. All of these results enriched the investigation between NAc and epilepsy, offering new targets for future epileptogenesis research and precision therapy.

Effects of psychogenic stress on oxidative stress and antioxidant capacity at different growth stages of rats: Experimental study

This study examined the psychogenic stress (PS) effects on changes in oxidative stress and the antioxidant capacity of an organism at different growth stages. The experimental animals were male Wistar rats of five different ages from growth periods (GPs) to old age. The growth stages were randomly classified into control (C) and experimental (PS) groups. The PS was performed using restraint and water immersion once daily for 3 h for 4 weeks. Reactive oxygen metabolites (d-ROMs) and the biological antioxidant potential (BAP) were measured before and after the experiment. In addition, the liver and adrenal glands were removed, and the wet weight was measured. The d-ROM and BAP of all growth stages given PS increased significantly. The d-ROM in the C group without PS increased significantly in GPs while decreased significantly in old-aged rats. In addition, the BAP of the C group in GP and early adulthood were all significantly elevated. There were significant differences in organ weights between the C and PS groups at all growth stages. Oxidative stress and antioxidant capacity differed depending on the organism's developmental status and growth stage, and PS also showed different effects. In particular, the variability in oxidative stress was remarkable, suggesting that the effect of PS was more significant in the organism's immature organs.

Stress and Epilepsy: Towards Understanding of Neurobiological Mechanisms for Better Management

Stress has been identified as a major contributor to human disease and is postulated to play a substantial role in epileptogenesis. In a significant proportion of individuals with epilepsy, sensitivity to stressful events contributes to dynamic symptomatic burden, notably seizure occurrence and frequency, and presence and severity of psychiatric comorbidities [anxiety, depression, posttraumatic stress disorder (PTSD)]. Here, we review this complex relationship between stress and epilepsy using clinical data and highlight key neurobiological mechanisms including the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, altered neuroplasticity within limbic system structures, and alterations in neurochemical pathways such as brain-derived neurotrophic factor (BNDF) linking epilepsy and stress. We discuss current clinical management approaches of stress that help optimize seizure control and prevention, as well as psychiatric comorbidities associated with epilepsy. We propose that various shared mechanisms of stress and epilepsy present multiple avenues for the development of new symptomatic and preventative treatments, including disease modifying therapies aimed at reducing epileptogenesis. This would require close collaborations between clinicians and basic scientists to integrate data across multiple scales, from genetics to systems biology, from clinical observations to fundamental mechanistic insights. In future, advances in machine learning approaches and neuromodulation strategies will enable personalized and targeted interventions to manage and ultimately treat stress-related epileptogenesis.

Adolescents' neural reactivity to acute psychosocial stress: dysfunctional regulation habits are linked to temporal gyrus response

Mid-adolescence is a critical time for the development of stress-related disorders and it is associated with significant social vulnerability. However, little is known about normative neural processes accompanying psychosocial stress at this time. Previous research found that emotion regulation strategies critically influence the relationship between stress and the development of psychiatric symptoms during adolescence. Using functional magnetic resonance imaging (fMRI), we examined neural responses to acute stress and analyzed whether the tendency to use adaptive or maladaptive emotion regulation strategies is related to neural and autonomic stress responses. Results show large linear activation increases from low to medium to high stress levels mainly in medial prefrontal, insulae and temporal areas. Caudate and subgenual anterior cingulate cortex, neural areas related to reward and affective valuations, showed linearly decreasing activation. In line with our hypothesis, the current adolescent neural stress profile resembled social rejection and was characterized by pronounced activation in insula, angular and temporal cortices. Moreover, results point to an intriguing role of the anterior temporal gyrus. Stress-related activity in the anterior temporal gyrus was positively related to maladaptive regulation strategies and stress-induced autonomic activity. Maladaptive coping might increase the social threat and reappraisal load of a stressor, relating to higher stress sensitivity of anterior temporal cortices.

A feasibility study to assess social stress and social support in patients enrolled in a cannabidiol (CBD) compassionate access program

Cannabidiol (CBD) trials offer an opportunity to examine social factors that shape outcomes of patients with treatment-resistant epilepsy. Prior research of patients treated with CBD for epilepsy describes financial struggles of these patients/families and the association between socioeconomic status and patient-centered outcomes. However, social determinants of health in this population are still poorly understood, mainly due to data scarcity. This study aimed to establish feasibility of assessing social stress, social support, and religious participation and their associations with outcomes (perceived health, quality of life, and mood) in patients treated with CBD for epilepsy. Data were collected during 2015-2018 through structured face-to face interviews with patients/caregivers in a CBD compassionate access/research program in the southern United States. Adult (ages 19-63; n = 65) and pediatric (ages 8-19; n = 46) patients or their caregivers were interviewed at the time of enrollment in the study. Social stress was assessed with stressful life events, perceived stress, epilepsy-related discrimination, and economic stressors; social support with the Interpersonal Support Evaluation List [ISEL]-12; and religious participation with frequency of religious attendance. The results showed economic stressors to be associated with poor overall health, but no associations were noted between stress, support, and religious participation measures and quality of life or mood. Despite a robust data collection plan, completeness of the data was mixed. We discuss lessons learned and directions for future research and identify potential refinements to social data collection in people with treatment-resistant epilepsy during clinical trials.

Cannabidiol normalizes resting-state functional connectivity in treatment-resistant epilepsy

OBJECTIVE

Resting-state (rs) network dysfunction is a contributing factor to treatment resistance in epilepsy. In treatment-resistant epilepsy (TRE), pharmacological and nonpharmacological therapies have been shown to improve such dysfunction. In this study, our goal was to prospectively evaluate the effect of highly purified plant-derived cannabidiol (CBD; Epidiolex®) on rs functional magnetic resonance imaging (fMRI) functional connectivity (rs-FC). We hypothesized that CBD would change and potentially normalize the rs-FC in TRE.

METHODS

Twenty-two of 27 participants with TRE completed all study procedures including longitudinal pre-/on-CBD rs-fMRI (8M/14F, mean age = 36.2 ± 15.9 years, TRE duration = 18.3 ± 12.6 years); there were no differences in age (p = 0.99) or sex (p = 0.15) between groups. Assessments collected included seizure frequency (SF), Chalfont Seizure Severity Scale (CSSS), Columbia Suicide Severity Rating Scale (C-SSRS), Adverse Events Profile (AEP), and Profile of Mood States (POMS). Twenty-three healthy controls (HCs) received rs-fMRI and POMS once.

RESULTS

Participants with TRE showed average decrease of 71.7% in SF (p < 0.0001) and improved CSSS, AEP, and POMS confusion, depression, and fatigue subscores (all p < 0.05) on-CBD with POMS scores becoming similar to those of HCs. Paired t-tests showed significant pre-/on-CBD changes in rs-FC in cerebellum, frontal areas, temporal areas, hippocampus, and amygdala with some of them correlating with improvement in behavioral measures. Significant differences in rs-FC between pre-CBD and HCs were found in cerebellum, frontal, and occipital regions. After controlling for changes in SF with CBD, these differences were no longer present when comparing on-CBD to HCs.

SIGNIFICANCE

This study indicates that highly purified CBD modulates and potentially normalizes rs-FC in the epileptic brain. This effect may underlie its efficacy. This study provides Class III evidence for CBD's normalizing effect on rs-FC in TRE.

A pilot study of combined endurance and resistance exercise rehabilitation for verbal memory and functional connectivity improvement in epilepsy

Memory impairment is common in persons with epilepsy (PWE), and exercise may be a strategy for its improvement. In this pilot study, we hypothesized that exercise rehabilitation would improve physical fitness and verbal memory and induce changes in brain networks involved in memory processes. We examined the effects of combined endurance and resistance exercise rehabilitation on memory and resting state functional connectivity (rsFC). Participants were randomized to exercise (PWE-E) or control (PWE-noE). The exercise intervention consisted of 18 supervised sessions on nonconsecutive days over 6 weeks. Before and after the intervention period, both groups completed self-report assessments (Short Form-36 (SF-36), Baecke Questionnaire (BQ) of habitual physical activity, and Profile of Mood States (POMS)), cognitive testing (California Verbal Learning Test-II (CVLT-II)), and magnetic resonance imaging (MRI); PWE-E also completed exercise performance tests. After completing the study, PWE-noE were offered cross-over to the exercise arm. There were no differences in baseline demographic, clinical, or assessment variables between 8 PWE-noE and 9 PWE-E. Persons with epilepsy that participated in exercise intervention increased maximum voluntary strength (all strength tests p < 0.05) and exhibited nonsignificant improvement in cardiorespiratory fitness (p = 0.15). Groups did not show significant changes in quality of life (QOL) or habitual physical activity between visits. However, there was an effect of visit on POMS total mood disturbance (TMD) measure showing improvement from baseline to visit 2 (p = 0.023). There were significant group by visit interactions on CVLT-II learning score (p = 0.044) and total recognition discriminability (d') (p = 0.007). Persons with epilepsy that participated in exercise intervention had significant reductions in paracingulate rsFC with the anterior cingulate and increases in rsFC for the cerebellum, thalamus, posterior cingulate cortex (PCC), and left and right inferior parietal lobule (IPL) (corrected p < 0.05). Change in CVLT-II learning score was associated with rsFC changes for the paracingulate cortex (r_S = -0.67; p = 0.0033), left IPL (r_S = 0.70; p = 0.0019), and right IPL (r_S = 0.71; p = 0.0015) while change in d' was associated with change in cerebellum rsFC to angular/middle occipital gyrus (r_S = 0.68; p = 0.0025). Our conclusion is that exercise rehabilitation may facilitate verbal memory improvement and brain network functional connectivity changes in PWE and that improved memory performance is associated with changes in rsFC. A larger randomized controlled trial of exercise rehabilitation for cognitive improvement in PWE is warranted.

Cortisol levels and seizures in adults with epilepsy: A systematic review

Stress has been suggested as a trigger factor for seizures in epilepsy patients, but little is known about cortisol levels, as indicators of stress, in adults with epilepsy. This systematic review summarizes the evidence on this topic. Following PRISMA guidelines, 38 articles were selected: 14 analyzing basal cortisol levels, eight examining antiepileptic drugs (AEDs) effects, 13 focused on seizure effects, and three examining stress. Higher basal cortisol levels were found in patients than in healthy people in studies with the most homogeneous samples (45% of 38 total studies). Despite heterogeneous results associated with AEDs, seizures were related to increases in cortisol levels in 77% of 38 total studies. The only study with acute stress administration found higher cortisol reactivity in epilepsy than in healthy controls. In studies using self-reported stress, high seizure frequency was related to increased cortisol levels and lower functional brain connectivity. Findings suggest that epilepsy could be considered a chronic stress model. The potential sensitizing role of accumulative seizures and issues for future research are discussed.

Epilepsy

Epilepsy affects all age groups and is one of the most common and most disabling neurological disorders. The accurate diagnosis of seizures is essential as some patients will be misdiagnosed with epilepsy, whereas others will receive an incorrect diagnosis. Indeed, errors in diagnosis are common, and many patients fail to receive the correct treatment, which often has severe consequences. Although many patients have seizure control using a single medication, others require multiple medications, resective surgery, neuromodulation devices or dietary therapies. In addition, one-third of patients will continue to have uncontrolled seizures. Epilepsy can substantially impair quality of life owing to seizures, comorbid mood and psychiatric disorders, cognitive deficits and adverse effects of medications. In addition, seizures can be fatal owing to direct effects on autonomic and arousal functions or owing to indirect effects such as drowning and other accidents. Deciphering the pathophysiology of epilepsy has advanced the understanding of the cellular and molecular events initiated by pathogenetic insults that transform normal circuits into epileptic circuits (epileptogenesis) and the mechanisms that generate seizures (ictogenesis). The discovery of >500 genes associated with epilepsy has led to new animal models, more precise diagnoses and, in some cases, targeted therapies.

Facial emotion processing in patients with seizure disorders

Studies of emotion processing are needed to better understand the pathophysiology of psychogenic nonepileptic seizures (PNES). We examined the differences in facial emotion processing between 12 patients with PNES, 12 patients with temporal lobe epilepsy (TLE), and 24 matched healthy controls (HCs) using fMRI with emotional faces task (EFT) (happy/sad/fearful/neutral) and resting state connectivity. Compared with TLE, patients with PNES exhibited increased fMRI response to happy, neutral, and fearful faces in visual, temporal, and/or parietal regions and decreased fMRI response to sad faces in the putamen bilaterally. Regions showing significant differences between PNES and TLE were used as functional seed regions of interest (ROIs), in addition to amygdala structural seed ROIs for resting state functional connectivity analyses. Whole brain analyses showed that compared with TLE and HCs, patients with PNES exhibited increased functional connectivity of the functional seed ROIs to several brain regions, particularly to cerebellar, visual, motor, and frontotemporal regions. Connectograms showed increased functional connections between left parahippocampal gyrus/uncus ROIs and right temporal ROIs in PNES compared with both the TLE and HC groups. Resting state functional connectivity of the left and right amygdala to various brain regions including emotion regulation and motor control circuits was increased in PNES when compared with those with TLE. This study provides preliminary evidence that patients with PNES exhibit altered facial emotion processing compared with patients with TLE and HCs and increased amygdala functional connectivity compared with TLE. These findings identify potential key differences in facial emotion processing reflective of neurophysiologic markers of neural circuitry alterations that can be used to generate further hypotheses for developing studies that examine the contributions of emotion processing to the development and maintenance of PNES.

Dysfunction in emotion processing underlies functional (psychogenic) dystonia

OBJECTIVE

We sought to determine whether abnormalities in emotion processing underlie functional (psychogenic) dystonia, one of the most common functional movement disorders.

METHODS

Motor and emotion circuits were examined in 12 participants with functional dystonia, 12 with primary organic dystonia, and 25 healthy controls using functional magnetic resonance imaging at 4T and a finger-tapping task (motor task), a basic emotion-recognition task (emotional faces task), and an intense-emotion stimuli task.

RESULTS

There were no differences in motor task activation between groups. In the faces task, when compared with the other groups, functional dystonia patients showed areas of decreased activation in the right middle temporal gyrus and bilateral precuneus and increased activation in the right inferior frontal gyrus, bilateral occipital cortex and fusiform gyrus, and bilateral cerebellum. In the intense-emotion task, when compared with the other groups, functional dystonia patients showed decreased activation in the left insular and left motor cortices (compared to organic dystonia, they showed an additional decrease in activation in the right opercular cortex and right motor cortex) and increased activation in the left fusiform gyrus.

CONCLUSIONS

Functional dystonia patients exhibited stimulus-dependent altered activation in networks involved in motor preparation and execution, spatial cognition, and attentional control. These results support the presence of network dysfunction in functional dystonia. © 2017 International Parkinson and Movement Disorder Society.

Impaired emotion processing in functional (psychogenic) tremor: A functional magnetic resonance imaging study

Background

Despite its high prevalence and associated disability, the neural correlates of emotion processing in patients with functional (psychogenic) tremor (FT), the most common functional movement disorder, remain poorly understood.

Methods

In this cross sectional functional magnetic resonance imaging (fMRI) study at 4T, 27 subjects with FT, 16 with essential tremor (ET), and 25 healthy controls (HCs) underwent a finger-tapping motor task, a basic-emotion task, and an intense-emotion task to probe motor and emotion circuitries. Anatomical and functional MRI data were processed with FSL (FMRIB Software Library) and AFNI (Analysis of Functional Neuroimages), followed by seed-to-seed connectivity analyses using anatomical regions defined from the Harvard-Oxford subcortical atlas; all analyses were corrected for multiple comparisons.

Results

After controlling for depression scores and correcting for multiple comparisons, the FT group showed increased activation in the right cerebellum compared to ET during the motor task; and increased activation in the paracingulate gyrus and left Heschl's gyrus compared with HC with decreased activation in the right precentral gyrus compared with ET during the basic-emotion task. No significant differences were found after adjusting for multiple comparisons during the intense-emotion task but increase in connectivity between the left amygdala and left middle frontal gyrus survived corrections in the FT subjects during this task, compared to HC.

Conclusions

In response to emotional stimuli, functional tremor is associated with alterations in activation and functional connectivity in networks involved in emotion processing and theory of mind. These findings may be relevant to the pathophysiology of functional movement disorders.

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Patients with functional tremor exhibit altered emotion processing circuitry.

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There is increased activation in the paracingulate gyrus after emotional stimuli.

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Increased connectivity between the left amygdala and middle frontal gyrus

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Functional disorders may be associated with disturbances in the theory of mind.

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.

Hypothalamic-pituitary-adrenocortical axis dysfunction in epilepsy

Epilepsy is a common neurological disease, affecting 2.4million people in the US. Among the many different forms of the disease, temporal lobe epilepsy (TLE) is one of the most frequent in adults. Recent studies indicate the presence of a hyperactive hypothalamopituitary- adrenocortical (HPA) axis and elevated levels of glucocorticoids in TLE patients. Moreover, in these patients, stress is a commonly reported trigger of seizures, and stress-related psychopathologies, including depression and anxiety, are highly prevalent. Elevated glucocorticoids have been implicated in the development of stress-related psychopathologies. Similarly, excess glucocorticoids have been found to increase neuronal excitability, epileptiform activity and seizure susceptibility. Thus, patients with TLE may generate abnormal stress responses that both facilitate ictal discharges and increase vulnerability for the development of comorbid psychopathologies. Here, we will examine the evidence that the HPA axis is disrupted in TLE, consider potential mechanisms by which this might occur, and discuss the implications of HPA dysfunction for seizuretriggering and psychiatric comorbidities.

Racial disparities in the diagnosis and management of trigeminal neuralgia

OBJECTIVE A number of studies have documented inequalities in care and outcomes for a variety of clinical conditions. The authors sought to identify racial and socioeconomic disparities in the diagnosis and treatment of trigeminal neuralgia (TN), as well as the potential underlying reasons for those disparities, which could serve as areas of focus for future quality improvement initiatives. METHODS The medical records of patients with an ICD-9 code of 350.1, signifying a diagnosis of TN, at the Henry Ford Medical Group (HFMG) in the period from 2006 to 2012 were searched, and clinical and socioeconomic data were retrospectively reviewed. Analyses were conducted to assess potential racial differences in subspecialty referral patterns and the specific type of treatment modality undertaken for patients with TN. RESULTS The authors identified 652 patients eligible for analysis. Compared with white patients, black patients were less likely to undergo percutaneous ablative procedures, stereotactic radiosurgery, or microvascular decompression (p < 0.001). However, there was no difference in the likelihood of blacks and whites undergoing a procedure once they had seen a neurosurgeon (67% vs 70%, respectively; p = 0.712). Blacks and whites were equally likely to be seen by a neurologist or neurosurgeon if they were initially seen in either the emergency room (38% vs 37%, p = 0.879) or internal medicine (48% vs 50%, p = 0.806). Among patients diagnosed (268 patients) after the 2008 publication of the European Federation of Neurological Societies and the American Academy of Neurology guidelines for medical therapy for TN, fewer than 50% were on medications sanctioned by the guidelines, and there were no statistically significant racial disparities between white and black patients (p = 0.060). CONCLUSIONS According to data from a large database from one of the nation's largest comprehensive health care systems, there were significant racial disparities in the likelihood of a patient undergoing a procedure for TN. This appeared to stem from outside HFMG from a difference in referral patterns to the neurologists and neurosurgeons.

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.

Stress and epilepsy: fact or fiction, and what can we do about it?

People with epilepsy report that stress is their most common trigger for seizures and some believe it caused their epilepsy in the first place. The extensive preclinical, epidemiological and clinical studies examining the link between stress and epilepsy have given confusing results; the clinical studies in particular are fraught with confounders. However stress is clearly bad for health, and we now have substantial preclinical evidence suggesting that chronic stress worsens epilepsy; in selected cases it may even be a causal factor for epilepsy. Healthcare professionals working with people with epilepsy should pay more attention to stress in clinical practice. This review includes some practical advice and guidance for stress screening and management.

Biomarkers in the diagnosis and study of psychogenic nonepileptic seizures: A systematic review

OBJECTIVE

Video electroencephalography (vEEG) is the gold-standard method for diagnosing psychogenic nonepileptic seizures (PNES), but such assessment is expensive, unavailable in many centers, requires prolonged hospitalization, and many times is unable to capture an actual seizure episode. This paper systematically reviews other non-vEEG candidate biomarkers that may facilitate both diagnosis and study of PNES as differentiated from epileptic seizures (ES).

METHODS

PubMed database was searched to identify articles between 1980 and 2015 (inclusion: adult PNES population with or without controls, English language; exclusion: review articles, meta-analyses, single case reports).

RESULTS

A total of 49 studies were examined, including neuroimaging, autonomic nervous system, prolactin, other (non-prolactin) hormonal, enzyme, and miscellaneous marker studies. Functional MRI studies have shown PNES is hyperlinked with dissociation and emotional dysregulation centers in the brain, although conflicting findings are seen across studies and none used psychiatric comparators. Heart rate variability suggests increased vagal tone in PNES when compared to ES. Prolactin is elevated in ES but not PNES, although shows low diagnostic sensitivity. Postictal cortisol and creatine kinase are nonspecific. Other miscellaneous biomarkers (neuron specific enolase, brain derived neurotropic factor, ghrelin, leptin, leukocytosis) showed no conclusive evidence of utility. Many studies are limited by lack of psychiatric comparators, size, and other methodological issues.

CONCLUSION

No single biomarker successfully differentiates PNES from ES; in fact, PNES is only diagnosed via the negation of ES. Clinical assessment and rigorous investigation of psychosocial variables specific to PNES remain critical, and subtyping of PNES is warranted. Future investigational and clinical imperatives are discussed.

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

Psychogenic nonepileptic seizures (PNES) are relatively common occurrences in epilepsy centers. Pathophysiology of PNES is still poorly understood. In this paper, the evidence for a neurobiological origin of PNES will be reviewed. Recent evidence suggests altered functional and structural brain connectivity as an underlying pathophysiological mechanism in patients with PNES. Pursuing the concept of connectome in patients with PNES and comparing the findings with healthy individuals may result in a breakthrough in identifying the exact neurobiological origin of PNES. Finding the neurobiological bases and identification of biomarkers of PNES will potentially have important clinical implications in formulating better diagnostic and therapeutic approaches for affected patients.

Uncinate fasciculus connectivity in patients with psychogenic nonepileptic seizures: A preliminary diffusion tensor tractography study

The amygdala, hippocampus, and medial prefrontal cortex are limbic brain regions connected by the uncinate fasciculus (UF) and implicated in emotion regulation. The aim of this study was to assess the connectivity characteristics of the UF in patients with psychogenic nonepileptic seizures (PNES) and matched healthy controls. We hypothesized that white matter connectivity of the UF in patients with PNES would differ from that in healthy controls. Eight patients with PNES and eight age- and sex-matched healthy controls underwent 3T MRI and 32-direction diffusion tensor imaging (DTI). Computation of DTI indices including fractional anisotropy (FA) and diffusion tensor tractography was performed. Two regions of interest were defined to manually trace the UF in each hemisphere for each subject. Fractional anisotropy and the number of reconstructed streamlines for the left and right hemispheres of the UF and the degree of asymmetry for each measure were compared between groups. Correlations between UF measures and clinical variables were also performed. Patients with PNES exhibited a significantly greater number of UF streamlines in the right hemisphere tract than in the left hemisphere (p=0.031), with such difference not observed in controls (p=0.81). This was reflected in a significant group difference in the asymmetry index (AI) for the number of streamlines, with more rightward asymmetry in patients with PNES (p=0.021). Average FA of the UF was similar between groups and between hemispheres for each group (all p>0.05). Age at illness onset was correlated with the AI for FA (r=-0.87; p=0.0045). Previously observed differences in emotion processing between controls and patients with PNES may be related to the differences in the rightward asymmetry in the number of UF streamlines in patients with PNES. Age at PNES onset appears to also have a role in the FA asymmetry of the UF. This is the first study to investigate the structural connectivity in these regions involved in emotional regulation in patients with PNES; further research is necessary to clarify the complex relationships between clinical measures and DTI characteristics.

Physiologic and cortical response to acute psychosocial stress in left temporal lobe epilepsy - a pilot cross-sectional fMRI study

Stress is commonly reported as a seizure precipitant in individuals with poorly controlled seizures including temporal lobe epilepsy. The aim of the study was to assess the neural and physiologic correlates of psychosocial stress response during functional magnetic resonance imaging (fMRI) and their relationship with seizure occurrence in patients with left temporal lobe epilepsy (LTLE). We enrolled 23 patients with LTLE and 23 age- and sex-matched healthy controls (HCs); all underwent fMRI with control math task (CMT) and stress math task (SMT) and pre-/post-fMRI salivary cortisol analysis (acute stress reactivity calculated as % reduction from post-stress to recovery baseline; dCORT). The Beck Depression Inventory-II (BDI-II) and Perceived Stress Scale (PSS-10) were administered. T-tests of performance and cortisol variables were performed. Processing and single-subject modeling of fMRI response to CMT positive feedback and SMT negative feedback, group comparisons, and whole-brain correlation of seizure occurrence and fMRI response in patients with poorly controlled LTLE were performed. Patients with LTLE and healthy controls were similar in demographics, math performance, heart rate, and PSS-10 scores (all p>0.05). Patients with LTLE exhibited greater dCORT (p=0.048) and lower BDI-II scores (p=0.016) compared with HCs. Patients with poorly controlled LTLE showed a positive association between seizure frequency and dCORT (r=0.73, p=0.016). Functional MRI activation to feedback was similar between groups, including midfrontal, temporal, parietal, and occipital regions. Regression analyses revealed no group differences to positive feedback, but, compared with HCs, patients with LTLE showed decreased activation to negative feedback in the left cerebellum/middle occipital/fusiform gyri, left hippocampus/parahippocampus, bilateral medial frontal/cingulate/superior frontal gyri, right postcentral gyrus/inferior parietal lobule, and right insula/postcentral gyrus (p<0.05, corrected). Patients with poorly controlled LTLE showed negative association between seizure frequency and activation in the bilateral subgenual anterior cingulate (p<0.05, corrected). This study is the first to characterize the cortical and physiologic responses to acute psychosocial stress and to show a significant relationship between seizure control in LTLE and both the hypothalamic-pituitary-adrenal axis and fMRI signal reactivity to acute psychosocial stress. These findings extend our understanding of the complex interplay between stress, physiologic stress markers, and seizures/epilepsy.