Postictal behavioural impairments are due to a severe prolonged hypoperfusion/hypoxia event that is COX-2 dependent

Postictal psychiatric symptoms: A neurophysiological study

OBJECTIVE

Postictal psychiatric symptoms (PPS) are a relatively common but understudied phenomenon in epilepsy. The mechanisms by which seizures contribute to worsening in psychiatric symptoms are unclear. We aimed to identify PPS prospectively during and after admission to the epilepsy monitoring unit (EMU) in order to characterize the postictal physiologic changes leading to PPS.

METHODS

We prospectively enrolled patients admitted to the EMU and administered repeat psychometric questionnaires during and after their hospital stay in order to assess for postictal exacerbations in four symptom complexes: anger/hostility, anxiety, depression, and paranoia. Electroclinical and electrographic seizures were identified from the EEG recordings, and seizure durations were measured. The severity of postictal slowing was calculated as the proportion of postictal theta/delta activity in the postictal EEG relative to the preictal EEG using the Hilbert transform.

RESULTS

Among 33 participants, 8 demonstrated significant increases in at least one of the four symptoms (the PPS+ group) within three days following the first seizure. The most common PPS was anger/hostility, experienced by 7/8 participants with PPS. Among the 8 PPS+ participants, four experienced more than one PPS. As compared to those without PPS (the PPS- group), the PPS+ group demonstrated a greater degree of postictal EEG slowing at 10 min (p = 0.022) and 20 min (p = 0.05) following seizure termination. They also experienced significantly more seizures during the study period (p = 0.005). There was no difference in seizure duration between groups.

SIGNIFICANCE

Postictal psychiatric symptoms including anger/hostility, anxiety, depression, and paranoia may be more common than recognized. In particular, postictal increases in anger and irritability may be particularly common. We provide physiological evidence of a biological mechanism as well as a demonstration of the use of quantitative electroencephalography toward a better understanding of postictal neurophysiology.

Ocular hemodynamics in epileptic children treated with antiepileptic drugs

PURPOSE

To evaluate the quantitative measurements obtained for vessel density (VD) of the optic nerve head, macula, peripapillary retinal nerve fibre layer (p-RNFL) and total retinal thicknesses (Trt) by optical coherence tomography angiography (OCT-A) and the choroidal vascular structure using an image binarization method in children with epilepsy using three different antiepileptic drugs (AEDs) and to compare these measurements with healthy participants.

METHODS

This observational, cross-sectional study included 124 patients divided into 4 groups: Group-1: patients receiving carbamazepine(n = 30), group-2: patients receiving levetiracetam (n = 31), group-3: patients receiving valproic acid (n = 32), and group 4: healthy controls (n = 31).A fully automated microstructural analysis of the VD of the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and the choriocapillaris (CC) layers and radial peripapillary capillary, and Trt, p-RNFL thickness were analyzed by using OCT-A. Enhanced depth imaging (EDI)-OCT scans of the macula were obtained and the images were binarized using the ImageJ software.

RESULTS

The mean age, gender distribution and the duration of epilepsy were similar in all groups. Evaluation of the p-RNFL thickness and perifoveal Trt between the groups showed a statistically significant difference in all quadrants.The p-RNFL thickness was lower in patients receiving carbamazepine and valproic acid. The lowest values of the luminal area and choroidal vascular index (CVI) were found in patients receiving valproic acid; comparison with matched healthy controls showed statistically significant differences.

CONCLUSION

Valproic acid and carbamazepine are associated with thinning of the p-RNFL in epilepsy patients, but the macular and radial peripapillary VD were not affected.However, a reduction of choroidal vascular blood flow was found in epilepsy patients taking valproic acid.

Association between retinal thickness and disease characteristics in adult epilepsy: A cross-sectional OCT evaluation

OBJECTIVE

Thinning of the peripapillary retinal nerve fiber layer (p-RNFL), as measured by optical coherence tomography (OCT), was recently introduced as a promising marker for cerebral neuronal loss in people with epilepsy (PwE). However, its clinical implication remains to be elucidated. We thus aimed to (1) systematically characterize the extent of the retinal neuroaxonal loss in a broad spectrum of unselected PwE and (2) to evaluate the main clinical determinants.

METHODS

In this prospective study, a spectral-domain OCT evaluation was performed on 98 well-characterized PwE and 85 healthy controls (HCs) (18-55 years of age). All inner retinal layers and the total macula volume were assessed. Group comparisons and linear regression analyses with stepwise backward selection were performed to identify relevant clinical and demographic modulators of the retinal neuroaxonal integrity.

RESULTS

PwE (age: 33.7 ± 10.6 years; 58.2% female) revealed a significant neuroaxonal loss across all assessed retinal layers (global pRNFL, P = 0.001, Δ = 4.24 μm; macular RNFL, P < 0.001, Δ = 0.05 mm3 ; ganglion cell inner plexiform layer, P < 0.001, Δ = 0.11 mm3 ; inner nuclear layer, INL, P = 0.03, Δ = 0.02 mm3 ) as well as significantly reduced total macula volumes (TMV, P < 0.001, Δ = 0.18 mm3 ) compared to HCs (age: 31.2 ± 9.0 years; 57.6% female). The extent of retinal neuroaxonal loss was associated with the occurrence and frequency of tonic-clonic seizures and the number of antiseizure medications, and was most pronounced in male patients.

SIGNIFICANCE

PwE presented an extensive retinal neuroaxonal loss, affecting not only the peripapillary but also macular structures. The noninvasive and economic measurement via OCT bears the potential to establish as a practical tool to inform patient management, as the extent of the retinal neuroaxonal loss reflects aspects of disease severity and sex-specific vulnerability.

PLAIN LANGUAGE SUMMARY

The retina is an extension of the brain and closely connected to it. Thus, cerebral alterations like atrophy reflect also on the retinal level. This is advantageous, as the retina is easily accessible and measureable with help of the optical coherence tomography. Here we report that adults with epilepsy have a significantly thinner retina than healthy persons. Especially people with many big seizures and a lot of medications have a thinner retina. We propose that measurement of the retina can be useful as a marker of disease severity and to inform patient management.

The "Curious Case of Postictal Oxygen Dissipation": Could ROS Be the Culprit?

Postictal Hypoxia Involves Reactive Oxygen Species and Is Ameliorated by Chronic Mitochondrial Uncoupling Villa BR, George AG, Shutt TE, Sullivan PG, Rho JM, Teskey GC. Neuropharmacology . 2023;238:109653. doi:10.1016/j.neuropharm.2023.109653 Prolonged severe hypoxia follows brief seizures and represents a mechanism underlying several negative postictal manifestations without interventions. Approximately 50% of the postictal hypoxia phenomenon can be accounted for by arteriole vasoconstriction. What accounts for the rest of the drop in unbound oxygen is unclear. Here, we determined the effect of pharmacological modulation of mitochondrial function on tissue oxygenation in the hippocampus of rats after repeatedly evoked seizures. Rats were treated with mitochondrial uncoupler 2,4 dinitrophenol (DNP) or antioxidants. Oxygen profiles were recorded using a chronically implanted oxygen-sensing probe, before, during, and after seizure induction. Mitochondrial function and redox tone were measured using in vitro mitochondrial assays and immunohistochemistry. Postictal cognitive impairment was assessed using the novel object recognition task. Mild mitochondrial uncoupling by DNP raised hippocampal oxygen tension and ameliorated postictal hypoxia. Chronic DNP also lowered mitochondrial oxygen-derived reactive species and oxidative stress in the hippocampus during postictal hypoxia. Uncoupling the mitochondria exerts therapeutic benefits on postictal cognitive dysfunction. Finally, antioxidants do not affect postictal hypoxia, but protect the brain from associated cognitive deficits. We provided evidence for a metabolic component of the prolonged oxygen deprivation that follow seizures and its pathological sequelae. Furthermore, we identified a molecular underpinning of this metabolic component, which involves excessive oxygen conversion into reactive species. Mild mitochondrial uncoupling may be a potential therapeutic strategy to treat the postictal state where seizure control is absent or poor.

Changes in postictal cerebral perfusion are related to the duration of electroconvulsive therapy-induced seizures

OBJECTIVE

Postictal symptoms may result from cerebral hypoperfusion, which is possibly a consequence of seizure-induced vasoconstriction. Longer seizures have previously been shown to cause more severe postictal hypoperfusion in rats and epilepsy patients. We studied cerebral perfusion after generalized seizures elicited by electroconvulsive therapy (ECT) and its relation to seizure duration.

METHODS

Patients with a major depressive episode who underwent ECT were included. During treatment, 21-channel continuous electroencephalogram (EEG) was recorded. Arterial spin labeling magnetic resonance imaging scans were acquired before the ECT course (baseline) and approximately 1 h after an ECT-induced seizure (postictal) to quantify global and regional gray matter cerebral blood flow (CBF). Seizure duration was assessed from the period of epileptiform discharges on the EEG. Healthy controls were scanned twice to assess test-retest variability. We performed hypothesis-driven Bayesian analyses to study the relation between global and regional perfusion changes and seizure duration.

RESULTS

Twenty-four patients and 27 healthy controls were included. Changes in postictal global and regional CBF were correlated with seizure duration. In patients with longer seizure durations, global decrease in CBF reached values up to 28 mL/100 g/min. Regional reductions in CBF were most prominent in the inferior frontal gyrus, cingulate gyrus, and insula (up to 35 mL/100 g/min). In patients with shorter seizures, global and regional perfusion increased (up to 20 mL/100 g/min). These perfusion changes were larger than changes observed in healthy controls, with a maximum median global CBF increase of 12 mL/100 g/min and a maximum median global CBF decrease of 20 mL/100 g/min.

SIGNIFICANCE

Seizure duration is a key factor determining postictal perfusion changes. In future studies, seizure duration needs to be considered as a confounding factor due to its opposite effect on postictal perfusion.

The Postictal Phase in Canine Idiopathic Epilepsy: Semiology, Management, and Impact on the Quality of Life from the Owners' Perspective

BACKGROUND

Dogs with idiopathic epilepsy experience not only the preictal and ictal seizure phases but also the postictal phase. To date, research has primarily focused on the preictal and ictal semiology and therapeutic control of ictal events. Research into the postictal phase's pathophysiology, as a therapeutic target and how it impacts the quality of life, is sparse across different species. Interestingly, even if anecdotally, owners report the postictal period being an impactful negative factor on their quality of life as well as their dog's quality of life.

HYPOTHESIS/OBJECTIVES

We aimed to assess the semiology and the impact of postictal signs on the quality of life of owners and dogs.

METHOD

This observational study was carried out using surveys of owners of dogs with seizure disorders.

RESULTS

The questionnaire was filled out by 432 dog owners, 292 of whom provided complete responses that could be analysed. More than nine out of ten owners (97%) reported the presence of various postictal clinical signs. The dog's and the owner's quality of life was mainly affected by specific postictal signs, i.e., disorientation (dog: 31%; owner: 20%), compulsive walking (dog: 17%; owner: 22%), ataxia (dog: 12%; owner: 6%), and blindness (dog: 17%; owner: 10%). Nearly 61% of the owners felt that the severity of postictal signs was moderate or severe. Rescue antiseizure medications did not have an effect on controlling the postictal signs based on 71% of the responders. In contrast, 77% of the respondents reported that other measures such as rest, physical closeness, and a quiet and dark environment had a positive impact on the postictal phase.

CONCLUSIONS AND CLINICAL IMPORTANCE

Overall, this survey shows that specific postictal signs are common and have a notable impact on the perceived quality of life of both dogs and their owners. According to the respondents, antiseizure medication might have no influence on the postictal phase in most cases, in contrast to other nonpharmacological measures. Further research on the management of the postictal phase is vital for improving the quality of life of dogs with seizure disorders and their owners.

Repeated episodes of postictal hypoxia are a mechanism for interictal cognitive impairments

Comorbidities during the period between seizures present a significant challenge for individuals with epilepsy. Despite their clinical relevance, the pathophysiology of the interictal symptomatology is largely unknown. Postictal severe hypoxia (PIH) in those brain regions participating in the seizure has been indicated as a mechanism underlying several negative postictal manifestations. It is unknown how repeated episodes of PIH affect interictal symptoms in epilepsy. Using a rat model, we observed that repeated seizures consistently induced episodes of PIH that become increasingly severe with each seizure occurrence. Additionally, recurrent seizure activity led to decreased levels of oxygen in the hippocampus during the interictal period. However, these reductions were prevented when we repeatedly blocked PIH using either the COX-inhibitor acetaminophen or the L-type calcium channel antagonist nifedipine. Moreover, we found that interictal cognitive deficits caused by seizures were completely alleviated by repeated attenuation of PIH events. Lastly, mitochondrial dysfunction may contribute to the observed pathological outcomes during the interictal period. These findings provide evidence that seizure-induced hypoxia may play a crucial role in several aspects of epilepsy. Consequently, developing and implementing treatments that specifically target and prevent PIH could potentially offer significant benefits for individuals with refractory epilepsy.

A case of temporary occlusion of donor artery after secondary generalized seizure in a patient with superficial temporal artery-middle cerebral artery bypass

Background

To prevent stroke recurrence, a superficial temporal artery-middle cerebral artery (STA-MCA) bypass for atherosclerotic cerebrovascular occlusive disease is performed. Post stroke epilepsy is known as serious sequelae of stroke. Herein, we present a case of a 60-year-old man who underwent STA-MCA bypass for the prevention of stroke recurrence; however, the donor artery was deemed to be temporally occluded secondary to generalized seizure.

Case Description

A 60-year-old man was referred to our hospital with a diagnosis of the left cervical internal carotid artery occlusion presenting with mild aphasia and right hemiparesis. He underwent STA-MCA bypass to prevent the recurrence of stroke 1 month after the onset of symptoms. On postoperative day 7, patency of the donor artery was confirmed on magnetic resonance imaging (MRI), and no complications were noted. However, on postoperative day 14, he presented with a secondary generalized seizure. MRI was immediately performed and the donor artery was not patent with no new lesions. Several hours thereafter, the blood flow of the donor artery was confirmed using pulse Doppler; however, during mouth opening, the flow of the donor artery decreased. Computed tomography-angiography confirmed donor artery patency. An encephalogram was conducted and revealed a focal epilepsy which was compatible with stroke on MRI.

Conclusion

Post stroke epilepsy caused an unintended and forced mouth opening which led to a temporary occlusion of the donor artery after STA-MCA bypass. Thus, this complication should be recognized, and seizures should be prevented through the administration of prophylactic anti-seizure medication based on risk stratification assessment of post stroke epilepsy.

SUDEP: A Local Low Pressure [pO2] System Makes It Hard to Breathe

Sudden Unexpected Death in Epilepsy Is Prevented by Blocking Postictal Hypoxia George AG, Farrell JS, Colangeli R, Wall AK, Gom RC, Kesler MT, Rodriguez de la Hoz C, Villa BR, Perera T, Rho JM, Kurrasch D, Teskey GC. Neuropharmacology . 2023;231:109513. doi:10.1016/j.neuropharm.2023.109513 . PMID: 36948357 Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments. Based on the observation that discrete seizures lead to local and postictal vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain we reasoned those similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of seizure-induced premature mortality, ibuprofen and nicardipine extended life while systemic drug levels remained high enough to be effective. We also examined the potential role of spreading depolarization in the acute model of seizure-induced premature mortality. These data provide a proof-of-principle for the neurovascular hypothesis of SUDEP rather than spreading depolarization and the use of currently available drugs to prevent it.

Caffeine exacerbates seizure-induced death via postictal hypoxia

Sudden unexpected death in epilepsy (SUDEP) is the leading epilepsy-related cause of premature mortality in people with intractable epilepsy, who are 27 times more likely to die than the general population. Impairment of the central control of breathing following a seizure has been identified as a putative cause of death, but the mechanisms underlying this seizure-induced breathing failure are largely unknown. Our laboratory has advanced a vascular theory of postictal behavioural dysfunction, including SUDEP. We have recently reported that seizure-induced death occurs after seizures invade brainstem breathing centres which then leads to local hypoxia causing breathing failure and death. Here we investigated the effects of caffeine and two adenosine receptors in two models of seizure-induced death. We recorded local oxygen levels in brainstem breathing centres as well as time to cessation of breathing and cardiac activity relative to seizure activity. The administration of the non-selective A1/A2A antagonist caffeine or the selective A1 agonist N6-cyclopentyladenosine reveals a detrimental effect on postictal hypoxia, providing support for caffeine modulating cerebral vasculature leading to brainstem hypoxia and cessation of breathing. Conversely, A2A activation with CGS-21680 was found to increase the lifespan of mice in both our models of seizure-induced death.

Technical feasibility of multimodal imaging in neonatal hypoxic-ischemic encephalopathy from an ovine model to a human case series

Hypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia occurs when the brain does not receive enough oxygen and blood. A surrogate marker for "intact survival" is necessary for the successful management of HIE. The severity of HIE can be classified based on clinical presentation, including the presence of seizures, using a clinical classification scale called Sarnat staging; however, Sarnat staging is subjective, and the score changes over time. Furthermore, seizures are difficult to detect clinically and are associated with a poor prognosis. Therefore, a tool for continuous monitoring on the cot side is necessary, for example, an electroencephalogram (EEG) that noninvasively measures the electrical activity of the brain from the scalp. Then, multimodal brain imaging, when combined with functional near-infrared spectroscopy (fNIRS), can capture the neurovascular coupling (NVC) status. In this study, we first tested the feasibility of a low-cost EEG-fNIRS imaging system to differentiate between normal, hypoxic, and ictal states in a perinatal ovine hypoxia model. Here, the objective was to evaluate a portable cot-side device and perform autoregressive with extra input (ARX) modeling to capture the perinatal ovine brain states during a simulated HIE injury. So, ARX parameters were tested with a linear classifier using a single differential channel EEG, with varying states of tissue oxygenation detected using fNIRS, to label simulated HIE states in the ovine model. Then, we showed the technical feasibility of the low-cost EEG-fNIRS device and ARX modeling with support vector machine classification for a human HIE case series with and without sepsis. The classifier trained with the ovine hypoxia data labeled ten severe HIE human cases (with and without sepsis) as the "hypoxia" group and the four moderate HIE human cases as the "control" group. Furthermore, we showed the feasibility of experimental modal analysis (EMA) based on the ARX model to investigate the NVC dynamics using EEG-fNIRS joint-imaging data that differentiated six severe HIE human cases without sepsis from four severe HIE human cases with sepsis. In conclusion, our study showed the technical feasibility of EEG-fNIRS imaging, ARX modeling of NVC for HIE classification, and EMA that may provide a biomarker of sepsis effects on the NVC in HIE.

Seizure-induced neutrophil adhesion in brain capillaries leads to a decrease in postictal cerebral blood flow

Cerebral hypoperfusion has been proposed as a potential cause of postictal neurological dysfunction in epilepsy, but its underlying mechanism is still unclear. We show that a 30% reduction in postictal cerebral blood flow (CBF) has two contributing factors: the early hypoperfusion up to ∼30 min post-seizure was mainly induced by arteriolar constriction, while the hypoperfusion that persisted for over an hour was due to increased capillary stalling induced by neutrophil adhesion to brain capillaries, decreased red blood cell (RBC) flow accompanied by constriction of capillaries and venules, and elevated intercellular adhesion molecule-1 (ICAM-1) expression. Administration of antibodies against the neutrophil marker Ly6G and against LFA-1, which mediates adhesive interactions with ICAM-1, prevented neutrophil adhesion and recovered the prolonged CBF reductions to control levels. Our findings provide evidence that seizure-induced neutrophil adhesion to cerebral microvessels via ICAM-1 leads to prolonged postictal hypoperfusion, which may underlie neurological dysfunction in epilepsy.

Ocular Perfusion Characteristics of Children with Newly Diagnosed Epilepsy

BACKGROUND

To investigate the vascular changes of the optic nerve head(ONH) and macula by using optical coherence tomography angiography(OCT-A), and also the choroidal vascular structure by using an image binarization tool in children with newly diagnosed epilepsy and to then compare these parameters with healthy subjects.

METHODS

Forty-one epilepsy children and 36 healthy controls were included in this prospective and cross-sectional study.The radial peripapillary capillary(RPC) vessel density(VD) and macular foveal,parafoveal,perifoveal of superficial capillary plexus(SCP),deep capillary plexus(DCP) and choriocapillaris(CC) VD, and CC flow area were analyzed.Enhanced depth imaging(EDI) OCT scans of the macula were obtained and the images were binarized using the ImageJ software (National Institutes of Health, Bethesda, MD, USA).The subfoveal choroidal thickness(SFCT),the area of choroidal, luminal, and interstitial and the percentage of luminal area in the choroid(Choroidal vascular index (CVI)) were analyzed.We also evaluated the thickness of the peripapillary retinal nerve fiber layer(RNFL),the macular ganglion cell layer(GCL), and the inner plexiform layer(IPL).

RESULTS

There was a significant decrease in the VD of the CC and the CC flow area in children with epilepsy compared to healthy subjects(p<0.05).However, the VD of the RPC, and of the SCP and DCP of the macula were similar between the two groups(p>0.05).The SFCT,choroidal area,luminal area, and CVI were statistically significant lower in children with newly diagnosed epilepsy compared to healthy subjects.

CONCLUSION

This study has demonstrated that the choroidal perfusion from the microcirculation is lower in children with newly diagnosed epilepsy.The pathophysiology of epilepsy and neurodegenerative processes may also include this vascular dysfunction as one of the factors.

Seizure duration predicts postictal electroencephalographic recovery after electroconvulsive therapy-induced seizures

OBJECTIVE

We aim to provide a quantitative description of the relation between seizure duration and the postictal state using features extracted from the postictal electroencephalogram (EEG).

METHODS

Thirty patients with major depressive disorder treated with electroconvulsive therapy (ECT) were studied with continuous EEG before, during, and after ECT-induced seizures. EEG recovery was quantified as the spectral difference between postictal and baseline EEG using the temporal brain symmetry index (BSI). The postictal temporal EEG evolution was modeled with a single exponential. The parameters of the model, including the time constant τ, describe the change and speed of postictal EEG recovery. The change from baseline EEG at t = 60 minutes post-seizure (ΔBSI) was calculated from the exponential fit. Postictal clinical reorientation time (ROT) was clinically established. A multivariate generalized multi-level Bayesian model was estimated with seizure duration and ROT as predictors of τ and ΔBSI.

RESULTS

EEG features of 290 seizures and postictal states were used for analyses. The model faithfully described the dynamics of the postictal EEG in nearly all patients. Seizure duration was associated with the recovery time constant, τ, and ΔBSI. ROT was associated with τ, but not with ΔBSI.

CONCLUSIONS

Longer seizures are associated with slower postictal EEG recovery and more enduring EEG changes compared to baseline.

SIGNIFICANCE

Quantitative EEG allows objective assessment of the postictal state.

Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia

Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments. Based on the observation that discrete seizures lead to local and postictal vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain we reasoned those similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of seizure-induced premature mortality, ibuprofen and nicardipine extended life while systemic drug levels remained high enough to be effective. We also examined the potential role of spreading depolarization in the acute model of seizure-induced premature mortality. These data provide a proof-of-principle for the neurovascular hypothesis of SUDEP rather than spreading depolarization and the use of currently available drugs to prevent it.

Focality in Febrile Seizures: A Retrospective Assessment Using Arterial Spin Labeling MRI

PURPOSE

 Defining focality of febrile seizures (FS) in clinical practice remains controversial. We investigated focality issues in FS with a postictal arterial spin labeling (ASL) sequence.

METHODS

 We retrospectively reviewed 77 children (median: 19.0 months, range: 15.0-33.0 months) who consecutively visited our emergency room for FS and underwent brain magnetic resonance imaging (MRI), including the ASL sequence, within 24 hours of seizure onset. ASL data were visually analyzed to assess perfusion changes. Factors related to the perfusion changes were investigated.

RESULTS

 The mean time to ASL acquisition was 7.0 (interquartile range: 4.0-11.0) hours. The most common seizure classification was unknown-onset seizures (n = 37, 48%), followed by focal-onset (n = 26, 34%) and generalized-onset seizures (n = 14, 18%). Perfusion changes were observed in 43 (57%) patients: most were hypoperfusion (n = 35, 83%). The temporal regions were the most common location of perfusion changes (n = 26, 60%); the majority of these were distributed in the unilateral hemisphere. Perfusion changes were independently associated with seizure classification (focal-onset seizures, adjusted odds ratio [aOR]: 9.6, p = 0.01; unknown-onset seizures aOR: 10.4, p < 0.01), and prolonged seizures (aOR: 3.1, p = 0.04), but not with other factors (age, sex, time to MRI acquisition, previous FS, repeated FS within 24 hour, family history of FS, structural abnormality on MRI, and developmental delay). The focality scale of seizure semiology positively correlated with perfusion changes (R = 0.334, p < 0.01).

CONCLUSION

 Focality in FS may be common, and its primary origin might be the temporal regions. ASL can be useful for assessing focality in FS, particularly when seizure onset is unknown.

Large-scale transient peri-ictal perfusion magnetic resonance imaging abnormalities detected by quantitative image analysis

Epileptic seizures require a rapid and safe diagnosis to minimize the time from onset to adequate treatment. Some epileptic seizures can be diagnosed clinically with the respective expertise. For more subtle seizures, imaging is mandatory to rule out treatable structural lesions and potentially life-threatening conditions. MRI perfusion abnormalities associated with epileptic seizures have been reported in CT and MRI studies. However, the interpretation of transient peri-ictal MRI abnormalities is routinely based on qualitative visual analysis and therefore reader dependent. In this retrospective study, we investigated the diagnostic yield of visual analysis of perfusion MRI during ictal and postictal states based on comparative expert ratings in 51 patients. We further propose an automated semi-quantitative method for perfusion analysis to determine perfusion abnormalities observed during ictal and postictal MRI using dynamic susceptibility contrast MRI, which we validated on a subcohort of 27 patients. The semi-quantitative method provides a parcellation of 3D T₁-weighted images into 32 standardized cortical regions of interests and subcortical grey matter structures based on a recently proposed method, direct cortical thickness estimation using deep learning-based anatomy segmentation and cortex parcellation for brain anatomy segmentation. Standard perfusion maps from a Food and Drug Administration-approved image analysis tool (Olea Sphere 3.0) were co-registered and investigated for region-wise differences between ictal and postictal states. These results were compared against the visual analysis of two readers experienced in functional image analysis in epilepsy. In the ictal group, cortical hyperperfusion was present in 17/18 patients (94% sensitivity), whereas in the postictal cohort, cortical hypoperfusion was present only in 9/33 (27%) patients while 24/33 (73%) showed normal perfusion. The (semi-)quantitative dynamic susceptibility contrast MRI perfusion analysis indicated increased thalamic perfusion in the ictal cohort and hypoperfusion in the postictal cohort. Visual ratings between expert readers performed well on the patient level, but visual rating agreement was low for analysis of subregions of the brain. The asymmetry of the automated image analysis correlated significantly with the visual consensus ratings of both readers. We conclude that expert analysis of dynamic susceptibility contrast MRI effectively discriminates ictal versus postictal perfusion patterns. Automated perfusion evaluation revealed favourable interpretability and correlated well with the classification of the visual ratings. It may therefore be employed for high-throughput, large-scale perfusion analysis in extended cohorts, especially for research questions with limited expert rater capacity.

Medication preventing postictal hypoperfusion and cognitive side-effects in electroconvulsive therapy: A retrospective cohort study

BACKGROUND

Electroconvulsive therapy (ECT) is associated with postictal confusion and cognitive side-effects. In rats, acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs) and calcium antagonists decreased postictal cerebral hypoperfusion along with reduction in postictal symptoms. In this study, in ECT-patients, we explore associations between use of these potentially protective medications and occurrence of postictal confusion and cognitive outcome.

MATERIALS AND METHODS

In this retrospective, naturalistic cohort study, patient-, treatment-, and ECT-characteristics, were collected from medical files of patients treated with ECT for major depressive disorder (MDD) or bipolar depressive episode. To test for associations of use of these medications with occurrence of postictal confusion, 295 patients could be included. Cognitive outcome data were available in a subset of 109 patients. Univariate analyses and multivariate censored regression models were used to test for associations.

RESULTS

Occurrence of severe postictal confusion was not associated with use of acetaminophen, NSAIDs or calcium antagonists (n = 295). Regarding the cognitive outcome measure (n = 109), use of calcium antagonists was associated with higher post-ECT cognitive scores (i.e., better cognitive outcome; β = 2.23; p = 0.047), adjusted for age (β = -0.02; p = 0.23), sex (β = -0.21; p = 0.73), pre-ECT cognitive score (β = 0.47; p < 0.0001), and post-ECT depression score (β = -0.02; p = 0.62), but use of acetaminophen (β = -1.55; p = 0.07) as well as NSAIDs (β = -1.02; p = 0.23) showed no associations.

CONCLUSION

This retrospective study does not find arguments for protective effects of acetaminophen, NSAIDs or calcium antagonists against severe postictal confusion in ECT. As a preliminary finding, the use of calcium antagonists was associated with improved cognitive outcome after ECT in this cohort. Prospective controlled studies are necessary.

Cerebral blood flow abnormalities with central sparing on arterial spin labeling in mild encephalopathy associated with excitotoxicity: a case report

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) and mild encephalopathy associated with excitotoxicity (MEEX) are the most frequent acute encephalopathies in pediatric patients in Japan. AESD typically presents with biphasic seizures and delayed reduced diffusion in the subcortical area, called bright tree appearance (BTA), on radiological examination. In patients with AESD, arterial spin labeling (ASL) shows decreased cerebral blood flow (CBF) in the hyperacute stage and increased CBF in the acute stage, suggesting the usefulness of ASL for the early diagnosis of AESD. Additionally, proton magnetic resonance spectroscopy (MRS) shows elevated glutamate (Glu) and glutamine (Gln) in AESD. MEEX is a group of mild encephalopathies with transient elevation of Gln on MRS similar to that in AESD; however, MEEX does not include any clinical biphasic course or abnormalities, including BTA on diffusion-weighted imaging. Although the usefulness of ASL for AESD has been reported, there are no reports for patients with MEEX. In this study, we report our experience with a 4-year-old girl diagnosed with MEEX who showed unique findings on ASL.

CASE PRESENTATION

The patient was a 4-year-old girl admitted to the emergency room with febrile status epilepticus. Considering the possibility of AESD, vitamin therapy was initiated. ASL-MR imaging (MRI) of the brain performed on the second day showed increased blood flow in the frontal, temporal, and occipital regions with spared central sulcus, which indicated AESD with central sparing. The patient was diagnosed with AESD, and the treatment included pulse steroid therapy and immunoglobulin therapy from day 3. The patient remained mildly unconscious but gradually became conscious by day 7 with no seizures. Brain MRI performed on day 8 did not show any characteristic AESD findings, such as BTA. Furthermore, MRS showed elevated Gln, which, along with the clinical course, led to the diagnosis of MEEX. The patient was discharged on day 16 without obvious sequelae.

CONCLUSIONS

ASL may be useful in the early diagnosis of MEEX as well as AESD, facilitating early intervention.

Brain tissue oxygen dynamics while mimicking the functional deficiency of interneurons

The dynamic interaction between excitatory and inhibitory activity in the brain is known as excitatory-inhibitory balance (EIB). A significant shift in EIB toward excitation has been observed in numerous pathological states and diseases, such as autism or epilepsy, where interneurons may be dysfunctional. The consequences of this on neurovascular interactions remains to be elucidated. Specifically, it is not known if there is an elevated metabolic consumption of oxygen due to increased excitatory activity. To investigate this, we administered microinjections of picrotoxin, a gamma aminobutyric acid (GABA) antagonist, to the rabbit cortex in the awake state to mimic the functional deficiency of GABAergic interneurons. This caused an observable shift in EIB toward excitation without the induction of seizures. We used chronically implanted electrodes to measure both neuronal activity and brain tissue oxygen concentrations (PO₂) simultaneously and in the same location. Using a high-frequency recording rate for PO₂, we were able to detect two important phenomena, (1) the shift in EIB led to a change in the power spectra of PO₂ fluctuations, such that higher frequencies (8-15 cycles per minute) were suppressed and (2) there were brief periods (dips with a duration of less than 100 ms associated with neuronal bursts) when PO₂ dropped below 10 mmHg, which we defined as the threshold for hypoxia. The dips were followed by an overshoot, which indicates either a rapid vascular response or decrease in oxygen consumption. Our results point to the essential role of interneurons in brain tissue oxygen regulation in the resting state.

Electrographic seizures and brain hyperoxia may be key etiological factors for post-concussive deficits

Repetitive mild traumatic brain injuries (RmTBIs) are increasingly recognized to have long-term neurological sequelae in a significant proportion of patients. Individuals that have had RmTBIs exhibit a variety of sensory, cognitive, or behavioral consequences that can negatively impact quality of life. Brain tissue oxygen levels (PO2) are normally maintained through exquisite regulation of blood supply to stay within the normoxic zone (18–30 mmHg in the rat hippocampus). However, during neurological events in which brain tissue oxygen levels leave the normoxic zone, neuronal dysfunction and behavioral deficits have been observed, and are frequently related to poorer prognoses. The oxygenation response in the brain after RmTBIs/repeated concussions has been poorly characterized, with most preliminary research limited to the neocortex. Furthermore, the mechanisms by which RmTBIs impact changes to brain oxygenation and vice versa remain to be determined. In the current study, we demonstrate that upon receiving RmTBIs, rats exhibit posttraumatic, electrographic seizures in the hippocampus, without behavioral (clinical) seizures, that are accompanied by a long-lasting period of hyperoxygenation. These electrographic seizures and the ensuing hyperoxic episodes are associated with deficits in working memory and motor coordination that were reversible through attenuation of the posttraumatic and postictal (postseizure) hyperoxia, via administration of a vasoconstricting agent, the calcium channel agonist Bay K8644. We propose that the posttraumatic period characterized by brain oxygenation levels well above the normoxic zone, may be the basis for some of the common symptoms associated with RmTBIs.

NEW & NOTEWORTHY We monitor oxygenation and electrographic activity in the hippocampus, immediately before and after mild traumatic brain injury. We demonstrate that as the number of injuries increases from 1 to 3, the proportion of rats that exhibit electrographic seizures and hyperoxia increases. Moreover, the presence of electrographic seizures and hyperoxia are associated with postinjury behavioral impairments, and if the hyperoxia is blocked with Bay K8644, the behavioral deficits are eliminated.

Sepsis modulates cortical excitability and alters the local and systemic hemodynamic response to seizures

Non-convulsive seizures and status epilepticus are frequent and associated with increased mortality in septic patients. However, the mechanism through which seizures impact outcome in these patients is unclear. As previous studies yielded an alteration of neurovascular coupling (NVC) during sepsis, we hypothesized that non-convulsive seizures, might further impair NVC, leading to brain tissue hypoxia. We used a previously developed ovine model of sepsis. Animals were allocated to sham procedure or sepsis; septic animals were studied either during the hyperdynamic phase (sepsis group) or after septic shock occurrence (septic shock group). After allocation, seizures were induced by cortical application of penicillin. We recorded a greater seizure-induced increase in the EEG gamma power in the sepsis group than in sham. Using a neural mass model, we also found that the theoretical activity of the modeled inhibitory interneurons, thought to be important to reproduce gamma oscillations, were relatively greater in the sepsis group. However, the NVC was impaired in sepsis animals, despite a normal brain tissue oxygenation. In septic shock animals, it was not possible to induce seizures. Cortical activity declined in case of septic shock, but it did not differ between sham or sepsis animals. As the alteration in NVC preceded cortical activity reduction, we suggest that, during sepsis progression, the NVC inefficiency could be partially responsible for the alteration of brain function, which might prevent seizure occurrence during septic shock. Moreover, we showed that cardiac output decreased during seizures in sepsis animals instead of increasing as in shams. The alteration of the seizure-induced systemic hemodynamic variations in sepsis might further affect cerebrovascular response to neuronal activation. Our findings support the hypothesis that anomalies in the cerebral blood flow regulation may contribute to the sepsis-associated encephalopathy and that seizures might be dangerous in such a vulnerable setting.

Ophthalmoparesis and Bilateral Ptosis as a Rare Manifestation of Todd's Phenomenon: Case Report and Review

Todd's paresis or phenomenon (TP) is a focal weakness in a part of the body after a seizure. Seizure is an abrupt change in behavior caused by the cerebral cortex's electrical hyper-synchronization of neuronal networks. After the seizure, there is usually a transition period from the ictal state to the pre-seizure baseline level of awareness and function, referred to as the postictal period. Postictal symptoms include many systems, including sensory, motor, and psychosis. This phenomenon is named after Robert Bentley Todd, who first described it. Todd's paresis can be confused with other conditions, most commonly a stroke. Postictal ocular manifestation may be accompanied by aphasia or hemiplegia, but isolated gaze palsy is rarely reported. We are reporting a rare and first known isolated ophthalmoparesis and ptosis as postictal findings with no structural abnormalities present in imaging studies and complete resolution over three weeks on its own as an atypical postictal phenomenon. Patients with an underlying structural abnormality of the brain are more susceptible to Todd's phenomenon. Unusual manifestations of Todd's phenomenon are rare but clinically relevant and are decisive in therapeutic decision-making. Our patient presents a rare manifestation of Todd's phenomenon as ptosis and ophthalmoparesis in an elderly male with no underlying structural brain abnormalities that resolved within three weeks. Further research into the causes is needed to distinguish it from a stroke

A fluorescent sensor for spatiotemporally resolved imaging of endocannabinoid dynamics in vivo

Endocannabinoids (eCBs) are retrograde neuromodulators with important functions in a wide range of physiological processes, but their in vivo dynamics remain largely uncharacterized. Here we developed a genetically encoded eCB sensor called GRAB_eCB2.0. GRAB_eCB2.0 consists of a circular-permutated EGFP and the human CB1 cannabinoid receptor, providing cell membrane trafficking, second-resolution kinetics with high specificity for eCBs, and shows a robust fluorescence response at physiological eCB concentrations. Using GRAB_eCB2.0, we monitored evoked and spontaneous changes in eCB dynamics in cultured neurons and acute brain slices. We observed spontaneous compartmentalized eCB transients in cultured neurons and eCB transients from single axonal boutons in acute brain slices, suggesting constrained, localized eCB signaling. When GRAB_eCB2.0 was expressed in the mouse brain, we observed foot shock-elicited and running-triggered eCB signaling in the basolateral amygdala and hippocampus, respectively. In a mouse model of epilepsy, we observed a spreading wave of eCB release that followed a Ca²⁺ wave through the hippocampus. GRAB_eCB2.0 is a robust probe for eCB release in vivo.

Study of effect of nimodipine and acetaminophen on postictal symptoms in depressed patients after electroconvulsive therapy (SYNAPSE)

Background

Postictal phenomena as delirium, headache, nausea, myalgia, and anterograde and retrograde amnesia are common manifestations after seizures induced by electroconvulsive therapy (ECT). Comparable postictal phenomena also contribute to the burden of patients with epilepsy. The pathophysiology of postictal phenomena is poorly understood and effective treatments are not available. Recently, seizure-induced cyclooxygenase (COX)-mediated postictal vasoconstriction, accompanied by cerebral hypoperfusion and hypoxia, has been identified as a candidate mechanism in experimentally induced seizures in rats. Vasodilatory treatment with acetaminophen or calcium antagonists reduced postictal hypoxia and postictal symptoms. The aim of this clinical trial is to study the effects of acetaminophen and nimodipine on postictal phenomena after ECT-induced seizures in patients suffering major depressive disorder. We hypothesize that (1) acetaminophen and nimodipine will reduce postictal electroencephalographic (EEG) phenomena, (2) acetaminophen and nimodipine will reduce magnetic resonance imaging (MRI) measures of postictal cerebral hypoperfusion, (3) acetaminophen and nimodipine will reduce clinical postictal phenomena, and (4) postictal phenomena will correlate with measures of postictal hypoperfusion.

Methods

We propose a prospective, three-condition cross-over design trial with randomized condition allocation, open-label treatment, and blinded end-point evaluation (PROBE design). Thirty-three patients (age > 17 years) suffering from a depressive episode treated with ECT will be included. Randomly and alternately, single doses of nimodipine (60 mg), acetaminophen (1000 mg), or water will be given two hours prior to each ECT session with a maximum of twelve sessions per patient. The primary outcome measure is ‘postictal EEG recovery time’, expressed and quantified as an adapted version of the temporal brain symmetry index, yielding a time constant for the duration of the postictal state on EEG. Secondary outcome measures include postictal cerebral perfusion, measured by arterial spin labelling MRI, and the postictal clinical ‘time to orientation’.

Discussion

With this clinical trial, we will systematically study postictal EEG, MRI and clinical phenomena after ECT-induced seizures and will test the effects of vasodilatory treatment intending to reduce postictal symptoms. If an effect is established, this will provide a novel treatment of postictal symptoms in ECT patients. Ultimately, these findings may be generalized to patients with epilepsy.

Trial registration

Inclusion in SYNAPSE started in December 2019. Prospective trial registration number is NCT04028596 on the international clinical trial register on July 22, 2019.

Sulforaphane Ameliorates Metabolic Changes Associated With Status Epilepticus in Immature Rats

Status epilepticus (SE) is a common paediatric emergency with the highest incidence in the neonatal period and is a well-known epileptogenic insult. As previously established in various experimental and human studies, SE induces long-term alterations to brain metabolism, alterations that directly contribute to the development of epilepsy. To influence these changes, organic isothiocyanate compound sulforaphane (SFN) has been used in the present study for its known effect of enhancing antioxidative, cytoprotective, and metabolic cellular properties via the Nrf2 pathway. We have explored the effect of SFN in a model of acquired epilepsy induced by Li-Cl pilocarpine in immature rats (12 days old). Energy metabolites PCr, ATP, glucose, glycogen, and lactate were determined by enzymatic fluorimetric methods during the acute phase of SE. Protein expression was evaluated by Western blot (WB) analysis. Neuronal death was scored on the FluoroJadeB stained brain sections harvested 24 h after SE. To assess the effect of SFN on glucose metabolism we have performed a series of 18F-DG μCT/PET recordings 1 h, 1 day, and 3 weeks after the induction of SE. Responses of cerebral blood flow (CBF) to electrical stimulation and their influence by SFN were evaluated by laser Doppler flowmetry (LDF). We have demonstrated that the Nrf2 pathway is upregulated in the CNS of immature rats after SFN treatment. In the animals that had undergone SE, SFN was responsible for lowering glucose uptake in most regions 1 h after the induction of SE. Moreover, SFN partially reversed hypometabolism observed after 24 h and achieved full reversal at approximately 3 weeks after SE. Since no difference in cell death was observed in SFN treated group, these changes cannot be attributed to differences in neurodegeneration. SFN per se did not affect the glucose uptake at any given time point suggesting that SFN improves endogenous CNS ability to adapt to the epileptogenic insult. Furthermore, we had discovered that SFN improves blood flow and accelerates CBF response to electrical stimulation. Our findings suggest that SFN improves metabolic changes induced by SE which have been identified during epileptogenesis in various animal models of acquired epilepsy.

Growth and differentiation factor-15 as a potential prognostic biomarker for status-epilepticus-associated-with-fever: A pilot study

OBJECTIVE

Biomarkers predicting poor outcomes of status-epilepticus-associated-with-fever (SEF) at an early stage may contribute to treatment guidance. However, none have been reported thus far. We investigated the dynamics of serum growth and differentiation factor (GDF)-15 after seizure onset in patients with SEF and determined whether GDF-15 can predict poor outcomes, particularly in the first 6 h after seizure onset.

METHODS

We enrolled 37 pediatric patients with SEF and eight patients with simple febrile seizures (SFS) and collected their blood samples within 24 h of seizure onset and eight febrile control patients between March 1, 2017 and September 30, 2020. All patients were aged ≤15 years.

RESULTS

In the SEF group, the median post-seizure serum GDF-15 values were 1,065 (<6h), 2,720 (6-12 h), and 2,411 (12-24 h) pg/mL. The median serum GDF-15 in the first 6 h was measured in patients with SEF without a significant past medical history (n = 21) and was found to be statistically significantly higher (1,587 pg/mL) than in the febrile control (551 pg/mL) and SFS (411 pg/mL) groups. The median serum GDF-15 was statistically significantly higher in patients with SEF with sequelae (n = 5) and patients with acute encephalopathy with biphasic seizures/reduced diffusion/hemorrhagic shock and encephalopathy syndrome (n = 6) than in patients with SEF without sequelae (n = 16) (15,898 vs 756 pg/mL) and patients with prolonged FS (n = 15) (9,448 vs 796 pg/mL).

CONCLUSIONS

This study demonstrates the dynamics of serum GDF-15 in patients with SEF and indicates the potential of GDF-15 as an early predictor of poor outcomes.

Brief neuronal afterdischarges in the rat hippocampus lead to transient changes in oscillatory activity and to a very long-lasting decline in BOLD signals without inducing a hypoxic state

The effects of hippocampal neuronal afterdischarges (nAD) on hemodynamic parameters, such as blood-oxygen-level-dependent (BOLD) signals) and local cerebral blood volume (CBV) changes, as well as neuronal activity and metabolic parameters in the dentate gyrus, was investigated in rats by combining in vivo electrophysiology with functional magnetic resonance imaging (fMRI) or ¹H-nuclear magnetic resonance spectroscopy (¹H-NMRS). Brief electrical high-frequency pulse-burst stimulation of the right perforant pathway triggered nAD, a seizure-like activity, in the right dentate gyrus with a high incidence, a phenomenon that in turn caused a sustained decrease in BOLD signals for more than 30 min. The decrease was associated with a reduction in CBV but not with signs of hypoxic metabolism. nAD also triggered transient changes mainly in the low gamma frequency band that recovered within 20 min, so that the longer-lasting altered hemodynamics reflected a switch in blood supply rather than transient changes in ongoing neuronal activity. Even in the presence of reduced baseline BOLD signals, neurovascular coupling mechanisms remained intact, making long-lasting vasospasm unlikely. Subsequently generated nAD did not further alter the baseline BOLD signals. Similarly, nAD did not alter baseline BOLD signals when acetaminophen was previously administered, because acetaminophen alone had already caused a similar decrease in baseline BOLD signals as observed after the first nAD. Thus, at least two different blood supply states exist for the hippocampus, one low and one high, with both states allowing similar neuronal activity. Both acetaminophen and nAD switch from the high to the low blood supply state. As a result, the hemodynamic response function to an identical stimulus differed after nAD or acetaminophen, although the triggered neuronal activity was similar.

Seizures induced in electroconvulsive therapy as a human epilepsy model: A comparative case study

OBJECTIVE

Standardized investigation of epileptic seizures and the postictal state may contribute to a better understanding of ictal and postictal phenomena. This comparative case study aims to assess whether electrically induced seizures in electroconvulsive therapy (ECT) show sufficient similarities with spontaneous seizures to serve as a human epilepsy model.

METHODS

We compared six EEG recordings, three ECT-induced seizures and three generalized tonic-clonic seizures, using quantitative electroencephalography (EEG) analyses. EEG recordings during and after ECT sessions (under general anesthesia and muscle paralysis) were collected prospectively, whereas epilepsy data were selected retrospectively. Time-frequency representations, dominant ictal frequencies, and postictal alpha-delta ratios were calculated.

RESULTS

In all EEG recordings, a decrease in dominant ictal frequency was observed, as well as postictal suppression. Postictal alpha-delta ratio indicated the same trend for all: a gradual increase from predominantly delta to alpha frequencies on timescales of hours after the seizure. Postictal spectral representation was similar. Muscle artifacts were absent in ECT-induced seizures and present in spontaneous seizures. Ictal amplitude was higher in epileptic than in ECT-induced seizures. Temporospectral ictal dynamics varied slightly between groups.

SIGNIFICANCE

We show that ictal and postictal characteristics in ECT and patients with generalized tonic-clonic seizures are essentially similar. ECT-induced seizures may be used to investigate aspects of ictal and postictal states in a highly predictable manner and well-controlled environment. This suggests that clinical and electrophysiological observations during ECT may be extrapolated to epilepsy with generalized tonic-clonic seizures.

Microvascular changes associated with epilepsy: A narrative review

The blood-brain barrier (BBB) is dysfunctional in temporal lobe epilepsy (TLE). In this regard, microvascular changes are likely present. The aim of this review is to provide an overview of the current knowledge on microvascular changes in epilepsy, and includes clinical and preclinical evidence of seizure induced angiogenesis, barriergenesis and microcirculatory alterations. Anatomical studies show increased microvascular density in the hippocampus, amygdala, and neocortex accompanied by BBB leakage in various rodent epilepsy models. In human TLE, a decrease in afferent vessels, morphologically abnormal vessels, and an increase in endothelial basement membranes have been observed. Both clinical and experimental evidence suggests that basement membrane changes, such as string vessels and protrusions, indicate and visualize a misbalance between endothelial cell proliferation and barriergenesis. Vascular endothelial growth factor (VEGF) appears to play a crucial role. Following an altered vascular anatomy, its physiological functioning is affected as expressed by neurovascular decoupling that subsequently leads to hypoperfusion, disrupted parenchymal homeostasis and potentially to seizures". Thus, epilepsy might be a condition characterized by disturbed cerebral microvasculature in which VEGF plays a pivotal role. Additional physiological data from patients is however required to validate findings from models and histological studies on patient biopsies.

Headache in people with epilepsy

Epidemiological estimates indicate that individuals with epilepsy are more likely to experience headaches, including migraine, than individuals without epilepsy. Headaches can be temporally unrelated to seizures, or can occur before, during or after an episode; seizures and migraine attacks are mostly not temporally linked. The pathophysiological links between headaches (including migraine) and epilepsy are complex and have not yet been fully elucidated. Correct diagnoses and appropriate treatment of headaches in individuals with epilepsy is essential, as headaches can contribute substantially to disease burden. Here, we review the insights that have been made into the associations between headache and epilepsy over the past 5 years, including information on the pathophysiological mechanisms and genetic variants that link the two disorders. We also discuss the current best practice for the management of headaches co-occurring with epilepsy and highlight future challenges for this area of research.

In vivo endocannabinoid dynamics at the timescale of physiological and pathological neural activity

The brain's endocannabinoid system is a powerful controller of neurotransmitter release, shaping synaptic communication under physiological and pathological conditions. However, our understanding of endocannabinoid signaling in vivo is limited by the inability to measure their changes at timescales commensurate with the high lability of lipid signals, leaving fundamental questions of whether, how, and which endocannabinoids fluctuate with neural activity unresolved. Using novel imaging approaches in awake behaving mice, we now demonstrate that the endocannabinoid 2-arachidonoylglycerol, not anandamide, is dynamically coupled to hippocampal neural activity with high spatiotemporal specificity. Furthermore, we show that seizures amplify the physiological endocannabinoid increase by orders of magnitude and drive the downstream synthesis of vasoactive prostaglandins that culminate in a prolonged stroke-like event. These results shed new light on normal and pathological endocannabinoid signaling in vivo.

The Good, the Bad, and the Deadly: Adenosinergic Mechanisms Underlying Sudden Unexpected Death in Epilepsy

Adenosine is an inhibitory modulator of neuronal excitability. Neuronal activity results in increased adenosine release, thereby constraining excessive excitation. The exceptionally high neuronal activity of a seizure results in a surge in extracellular adenosine to concentrations many-fold higher than would be observed under normal conditions. In this review, we discuss the multifarious effects of adenosine signaling in the context of epilepsy, with emphasis on sudden unexpected death in epilepsy (SUDEP). We describe and categorize the beneficial, detrimental, and potentially deadly aspects of adenosine signaling. The good or beneficial characteristics of adenosine signaling in the context of seizures include: (1) its direct effect on seizure termination and the prevention of status epilepticus; (2) the vasodilatory effect of adenosine, potentially counteracting postictal vasoconstriction; (3) its neuroprotective effects under hypoxic conditions; and (4) its disease modifying antiepileptogenic effect. The bad or detrimental effects of adenosine signaling include: (1) its capacity to suppress breathing and contribute to peri-ictal respiratory dysfunction; (2) its contribution to postictal generalized EEG suppression (PGES); (3) the prolonged increase in extracellular adenosine following spreading depolarization waves may contribute to postictal neuronal dysfunction; (4) the excitatory effects of A2A receptor activation is thought to exacerbate seizures in some instances; and (5) its potential contributions to sleep alterations in epilepsy. Finally, the adverse effects of adenosine signaling may potentiate a deadly outcome in the form of SUDEP by suppressing breathing and arousal in the postictal period. Evidence from animal models suggests that excessive postictal adenosine signaling contributes to the pathophysiology of SUDEP. The goal of this review is to discuss the beneficial, harmful, and potentially deadly roles that adenosine plays in the context of epilepsy and to identify crucial gaps in knowledge where further investigation is necessary. By better understanding adenosine dynamics, we may gain insights into the treatment of epilepsy and the prevention of SUDEP.

Diagnostic Accuracy of Arterial Spin-Labeling MR Imaging in Detecting the Epileptogenic Zone: Systematic Review and Meta-analysis

BACKGROUND

A noninvasive, safe, and economic imaging technique is required to identify epileptogenic lesions in the brain.

PURPOSE

Our aim was to perform a meta-analysis evaluating the accuracy of arterial spin-labeling in localizing the epileptic focus in the brain and the changes in the blood perfusion in these regions.

DATA SOURCES

Our sources were the PubMed and EMBASE data bases.

STUDY SELECTION

English language studies that assessed the diagnostic accuracy of arterial spin-labeling for detecting the epileptogenic zone up to July 2019 were included.

DATA ANALYSIS

The symptomatogenic foci of seizures in the brain were determined and used as the references. The relevant studies were evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The outcomes were evaluated using the pooled sensitivity, pooled specificity, pooled accuracy, diagnostic odds ratio, area under the summary receiver operating characteristic curve, and likelihood ratio.

DATA SYNTHESIS

Six studies that included 174 patients qualified for this meta-analysis. The pooled sensitivity, pooled specificity, and area under the summary receiver operating characteristic curve were 0.74 (95% CI, 0.65-0.82), 0.35 (95% CI, 0.03-0.90), and 0.73 (95% CI, 0.69-0.76), respectively. The accuracy of arterial spin-labeling for localizing the epileptic focus was 0.88 (accuracy in arterial spin-labeling/all perfusion changes in arterial spin-labeling) in cases of a positive arterial spin-labeling result. The epileptogenic zone exhibited hyperperfusion or hypoperfusion.

LIMITATIONS

Only a few studies were enrolled due to the strict inclusion criteria.

CONCLUSIONS

Arterial spin-labeling can be used for assessing, monitoring, and reviewing, postoperatively, patients with epilepsy. Blood perfusion changes in the brain may be closely related to the seizure time and pattern.

An interictal measurement of cerebral oxygen extraction fraction in MRI-negative refractory epilepsy using quantitative susceptibility mapping

PURPOSE

Oxygen extraction fraction (OEF) can be a factor to identify brain tissue's disability in epileptic patients. This study aimed to assess the OEF's level measurement in refractory epileptic patients (REPs) using a quantitative susceptibility mapping (QSM) method and to determine whether the OEF parameters change.

METHODS

QSM-OEF maps of 26 REPs and 16 healthy subjects were acquired using 3T MRI with a 64-channel coil. Eighteen regions-of-interest (ROIs) were chosen around the cortex in one appropriate slice of the brain and the mean QSM-OEF for each ROI was obtained. The correlations of QSM-OEF among different clinical characteristics of the disease, as well as between the patients and normal subjects, were also investigated.

RESULTS

QSM-OEF was shown to be significantly higher in REPs (44.9 ± 5.8) than that in HS (41.9 ± 6.2) (p < 0.05). Mean QSM-OEF was statistically lower in the ipsilateral side (44.5 ± 6.6) compared to the contralateral side (46.4 ± 6.8) (P < 0.01). QSM-OEF was illustrated to have a strong positive correlation with the attack duration (r = 0.6), and a moderate negative correlation with the attack frequency (r = -0.3). Using an optimized support vector machine algorithm, we could predict the disease in subjects having abnormal OEF values in the brain-selected-ROIs with sensitivity, specificity, AUC, and the precision of 0.96, 1, 0.98, and 1, respectively.

CONCLUSIONS

The results of this study revealed that QSM-OEF of the REPs' brain is higher than that of HS, which indicates that QSM-OEF is associated with disease activity.

Differential contribution of excitatory and inhibitory neurons in shaping neurovascular coupling in different epileptic neural states

Understanding the neurovascular coupling (NVC) underlying hemodynamic changes in epilepsy is crucial to properly interpreting functional brain imaging signals associated with epileptic events. However, how excitatory and inhibitory neurons affect vascular responses in different epileptic states remains unknown. We conducted real-time in vivo measurements of cerebral blood flow (CBF), vessel diameter, and excitatory and inhibitory neuronal calcium signals during recurrent focal seizures. During preictal states, decreases in CBF and arteriole diameter were closely related to decreased γ-band local field potential (LFP) power, which was linked to relatively elevated excitatory and reduced inhibitory neuronal activity levels. Notably, this preictal condition was followed by a strengthened ictal event. In particular, the preictal inhibitory activity level was positively correlated with coherent oscillating activity specific to inhibitory neurons. In contrast, ictal states were characterized by elevated synchrony in excitatory neurons. Given these findings, we suggest that excitatory and inhibitory neurons differentially contribute to shaping the ictal and preictal neural states, respectively. Moreover, the preictal vascular activity, alongside with the γ-band, may reflect the relative levels of excitatory and inhibitory neuronal activity, and upcoming ictal activity. Our findings provide useful insights into how perfusion signals of different epileptic states are related in terms of NVC.

The ketogenic diet raises brain oxygen levels, attenuates postictal hypoxia, and protects against learning impairments

OBJECTIVES

A prolonged vasoconstriction/hypoperfusion/hypoxic event follows self-terminating focal seizures. The ketogenic diet (KD) has demonstrated efficacy as a metabolic treatment for intractable epilepsy and other disorders but its effect on local brain oxygen levels is completely unknown. This study investigated the effects of the KD on tissue oxygenation in the hippocampus before and after electrically elicited (kindled) seizures and whether it could protect against a seizure-induced learning impairment. We also examined the effects of the ketone β-hydroxybutyrate (BHB) as a potential underlying mechanism.

METHODS

Male and female rats were given access to one of three diet protocols 2 weeks prior to the initiation of seizures: KD, caloric restricted standard chow, and ad libitum standard chow. Dorsal hippocampal oxygen levels were measured prior to initiation of diets as well as before and after a 10-day kindling paradigm. Male rats were then tested on a novel object recognition task to assess postictal learning impairments. In a separate cohort, BHB was administered 30 min prior to seizure elicitation to determine whether it influenced oxygen dynamics.

RESULTS

The KD increased dorsal hippocampal oxygen levels, ameliorated postictal hypoxia, and prevented postictal learning impairments. Acute BHB administration did not alter oxygen levels before or after seizures.

INTERPRETATION

The ketogenic diet raised brain oxygen levels and attenuated severe postictal hypoxia likely through a mechanism independent of ketosis and shows promise as a non-pharmacological treatment to prevent the postictal state.

Noninvasive transcranial focal stimulation affects the convulsive seizure-induced P-glycoprotein expression and function in rats

Transcranial focal stimulation (TFS) is a noninvasive neuromodulation strategy that reduces seizure activity in different experimental models. Nevertheless, there is no information about the effects of TFS in the drug-resistant phenotype associated with P-glycoprotein (Pgp) overexpression. The present study focused on determining the effects of TFS on Pgp expression after an acute seizure induced by 3-mercaptopropionic acid (MPA). P-glycoprotein expression was analyzed by western blot in the cerebral cortex and hippocampus of rats receiving 5 min of TFS (300 Hz, 50 mA, 200 μs, biphasic charge-balanced squared pulses) using a tripolar concentric ring electrode (TCRE) prior to administration of a single dose of MPA. An acute administration of MPA induced Pgp overexpression in cortex (68 ± 13.4%, p < 0.05 vs the control group) and hippocampus (48.5 ± 14%, p < 0.05, vs the control group). This effect was avoided when TFS was applied prior to MPA. We also investigated if TFS augments the effects of phenytoin in an experimental model of drug-resistant seizures induced by repetitive MPA administration. Animals with MPA-induced drug-resistant seizures received TFS alone or associated with phenytoin (75 mg/kg, i.p.). TFS alone did not modify the expression of the drug-resistant seizures. However, TFS combined with phenytoin reduced seizure intensity, an effect associated with a lower prevalence of major seizures (50%, p = 0.03 vs phenytoin alone). Our experiments demonstrated that TFS avoids the Pgp overexpression induced after an acute convulsive seizure. In addition, TFS augments the phenytoin effects in an experimental model of drug-resistant seizures. According with these results, it is indicated that TFS may represent a new neuromodulatory strategy to revert the drug-resistant phenotype.

Visualizing prolonged hyperperfusion in post-stroke epilepsy using postictal subtraction SPECT

Diagnosis of post-stroke epilepsy is often challenging because of a low incidence of epileptiform abnormalities on electroencephalography (EEG). Hence, this study evaluated whether postictal subtraction single-photon emission computed tomography (SPECT) could visualize epileptic activity and act as a diagnostic modality in post-stroke epilepsy. Fifty post-stroke epilepsy patients, who had undergone Tc-99m-ECD SPECT twice (postictal and interictal), were enrolled. The postictal hyperperfusion area was identified by subtraction (postictal-interictal) SPECT and classified into two distribution types: superficial or deep-seated. Laterality and distribution of postictal hyperperfusion on subtraction SPECT were compared with stroke lesions, seizure symptoms, and epileptiform EEG findings. Forty-three of the 50 patients (86%) had hyperperfusion on subtraction SPECT and 26 (52%) had epileptiform EEG findings. Subtraction SPECT showed prolonged postictal hyperperfusion despite the relatively long interval between seizure end and postictal SPECT (median: 19.1 h, range: 2.2-112.5 h). The laterality of the hyperperfusion area had a high concordance rate with the laterality of stroke lesions (97.7%), seizure symptoms (91.9%), and epileptiform EEG findings (100%). Scalp EEG identified epileptiform activity more frequently in superficial type of SPECT, but less frequently in deep-seated type (both, P = 0.03). Postictal SPECT can be complementary to scalp EEG in endorsing the diagnosis and location of post-stroke epilepsy.

Seizures elevate gliovascular unit Ca2+ and cause sustained vasoconstriction

Seizures can result in a severe hypoperfusion/hypoxic attack that causes postictal memory and behavioral impairments. However, neither postictal changes to microvasculature nor Ca²⁺ changes in key cell types controlling blood perfusion have been visualized in vivo, leaving essential components of the underlying cellular mechanisms unclear. Here, we use 2-photon microvascular and Ca²⁺ imaging in awake mice to show that seizures result in a robust vasoconstriction of cortical penetrating arterioles, which temporally mirrors the prolonged postictal hypoxia. The vascular effect was dependent on cyclooxygenase 2, as pretreatment with ibuprofen prevented postictal vasoconstriction. Moreover, seizures caused a rapid elevation in astrocyte endfoot Ca²⁺ that was confined to the seizure period, and vascular smooth muscle cells displayed a significant increase in Ca²⁺ both during and following seizures, lasting up to 75 minutes. Our data show enduring postictal vasoconstriction and temporal activities of 2 cell types within the neurovascular unit that are associated with seizure-induced hypoperfusion/hypoxia. These findings support prevention of this event may be a novel and tractable treatment strategy in patients with epilepsy who experience extended postseizure impairments.

Seizures cause enduring microvascular constriction via long lasting calcium elevations in vascular smooth muscle cells.

In vivo assessment of mechanisms underlying the neurovascular basis of postictal amnesia

Long-lasting confusion and memory difficulties during the postictal state remain a major unmet problem in epilepsy that lacks pathophysiological explanation and treatment. We previously identified that long-lasting periods of severe postictal hypoperfusion/hypoxia, not seizures per se, are associated with memory impairment after temporal lobe seizures. While this observation suggests a key pathophysiological role for insufficient energy delivery, it is unclear how the networks that underlie episodic memory respond to vascular constraints that ultimately give rise to amnesia. Here, we focused on cellular/network level analyses in the CA1 of hippocampus in vivo to determine if neural activity, network oscillations, synaptic transmission, and/or synaptic plasticity are impaired following kindled seizures. Importantly, the induction of severe postictal hypoperfusion/hypoxia was prevented in animals treated by a COX-2 inhibitor, which experimentally separated seizures from their vascular consequences. We observed complete activation of CA1 pyramidal neurons during brief seizures, followed by a short period of reduced activity and flattening of the local field potential that resolved within minutes. During the postictal state, constituting tens of minutes to hours, we observed no changes in neural activity, network oscillations, and synaptic transmission. However, long-term potentiation of the temporoammonic pathway to CA1 was impaired in the postictal period, but only when severe local hypoxia occurred. Lastly, we tested the ability of rats to perform object-context discrimination, which has been proposed to require temporoammonic input to differentiate between sensory experience and the stored representation of the expected object-context pairing. Deficits in this task following seizures were reversed by COX-2 inhibition, which prevented severe postictal hypoxia. These results support a key role for hypoperfusion/hypoxia in postictal memory impairments and identify that many aspects of hippocampal network function are resilient during severe hypoxia except for long-term synaptic plasticity.

Quantitative T2 MRI is predictive of neurodegeneration following organophosphate exposure in a rat model

Organophosphorus compounds, such as chemical warfare nerve agents and pesticides, are known to cause neurological damage. This study measured nerve agent-related neuropathology and determined whether quantitative T₂ MRI could be used as a biomarker of neurodegeneration. Quantitative T₂ MRI was performed using a 9.4 T MRI on rats prior to and following soman exposure. T₂ images were taken at least 24 h prior, 1 h and 18-24 h after soman exposure. Rats were pre- and post-treated with HI-6 dimethanesulfonate and atropine methyl nitrate. A multicomponent T₂ acquisition and analysis was performed. Brains were stained with Fluoro-Jade C to assess neurodegeneration. Rats exposed to soman developed behavioral expression of electrographic seizures. At 18-24 h after soman exposure, significant increases in T₂, a possible marker of edema, were found in multiple regions. The largest changes were in the piriform cortex (before: 47.7 ± 1.4 ms; 18-24 h: 82.3 ± 13.4 ms). Fluoro-Jade C staining showed significant neurodegeneration 18-24 h post exposure. The piriform cortex had the strongest correlation between the change in relaxation rate and percent neurodegeneration (r = 0.96, p < 0.001). These findings indicate there is regionally specific neurodegeneration 24 h after exposure to soman. The high correlation between T₂ relaxivity and histopathology supports the use of T₂ as a marker of injury.

Postictal brainstem hypoperfusion and risk factors for sudden unexpected death in epilepsy

OBJECTIVE

Since the strongest risk factor for sudden unexpected death in epilepsy (SUDEP) is frequent bilateral tonic-clonic seizures (BTCS), our aim was to determine whether postictal hypoperfusion in brainstem respiratory centers (BRCs) is more common following tonic-clonic seizures.

METHODS

We studied 21 patients with focal epilepsies who underwent perfusion imaging with arterial spin labeling MRI. Subtraction maps of cerebral blood flow were obtained from the postictal and baseline scans. We identified 6 regions of interest in the brainstem that contain key BRCs. Patients were considered to have postictal BRC hypoperfusion if any of the 6 regions of interest were significantly hypoperfused.

RESULTS

All 6 patients who experienced BTCS during the study had significant clusters of postictal hypoperfusion in BRCs compared to 7 who had focal impaired awareness seizures (7/15). The association between seizure type studied and the presence of BRC hypoperfusion was significant. Duration of epilepsy and frequency of BTCS were not associated with postictal brainstem hypoperfusion despite also being associated with risk for SUDEP.

CONCLUSION

Postictal hypoperfusion in brainstem respiratory centers occurs more often following BTCS than other seizure types, providing a possible explanation for the increased risk of SUDEP in patients who regularly experience BTCS.

The lncRNA H19 binding to let-7b promotes hippocampal glial cell activation and epileptic seizures by targeting Stat3 in a rat model of temporal lobe epilepsy

Objectives

Glial cell activation contributes to the inflammatory response and occurrence of epilepsy. Our preliminary study demonstrated that the long non‐coding RNA, H19, promotes hippocampal glial cell activation during epileptogenesis. However, the precise mechanisms underlying this effect remain unclear.

Materials and methods

H19 and let‐7b were overexpressed or silenced using an adeno‐associated viral vector in vivo. Their expression in a kainic acid‐induced epilepsy model was evaluated by real‐time quantitative PCR, fluorescence in situ hybridization, and cytoplasmic and nuclear RNA isolation. A dual‐luciferase reporter assay was used to evaluate the direct binding of let‐7b to its target genes and H19. Western blot, video camera monitoring and Morris water maze were performed to confirm the role of H19 and let7b on epileptogenesis.

Results

H19 was increased in rat hippocampus neurons after status epilepticus, which might be due to epileptic seizure‐induced hypoxia. Increased H19 aggravated the epileptic seizures, memory impairment and mossy fibre sprouting of the epileptic rats. H19 could competitively bind to let‐7b to suppress its expression. Overexpression of let‐7b inhibited hippocampal glial cell activation, inflammatory response and epileptic seizures by targeting Stat3. Moreover, overexpressed H19 reversed the inhibitory effect of let‐7b on glial cell activation.

Conclusions

LncRNA H19 could competitively bind to let‐7b to promote hippocampal glial cell activation and epileptic seizures by targeting Stat3 in a rat model of temporal lobe epilepsy.

Dynamic oxygen changes during status epilepticus and subsequent endogenous kindling

OBJECTIVE

Brain tissue oxygen (partial oxygen pressure [pO2 ]) levels are tightly regulated to stay within the normoxic zone, with deviations on either side resulting in impaired brain function. Whereas pathological events such as ischemic attacks and brief seizures have previously been shown to result in pO2 levels well below the normoxic zone, oxygen levels during prolonged status epilepticus (SE) and the subsequent endogenous kindling period are unknown.

METHODS

We utilized two models of acquired temporal lobe epilepsy in rats: intrahippocampal kainic acid infusion and prolonged perforant pathway stimulation. Local tissue oxygen was measured in the dorsal hippocampus using an optode during and for several weeks following SE.

RESULTS

We observed hyperoxia in the hippocampus during induced SE in both models. Following termination of SE, 88% of rats initiated focal self-generated spiking activity in the hippocampus within the first 7 days, which was associated with dynamic oxygen changes. Self-generated and recurring epileptiform activity subsequently organized into higher-frequency bursts that became progressively longer and were ultimately associated with behavioral seizures that became more severe with time and led to postictal hypoxia.

SIGNIFICANCE

Induced SE and self-generated recurrent epileptiform activity can have profound and opposing effects on brain tissue oxygenation that may serve as a biomarker for ongoing pathological activity in the brain.

Anandamide Signaling Augmentation Rescues Amygdala Synaptic Function and Comorbid Emotional Alterations in a Model of Epilepsy

Epilepsy is often associated with emotional disturbances and the endocannabinoid (eCB) system tunes synaptic transmission in brain regions regulating emotional behavior. Thus, persistent alteration of eCB signaling after repeated seizures may contribute to the development of epilepsy-related emotional disorders. Here we report that repeatedly eliciting seizures (kindling) in the amygdala caused a long-term increase in anxiety and impaired fear memory retention, which was paralleled by an imbalance in GABA/glutamate presynaptic activity and alteration of synaptic plasticity in the basolateral amygdala (BLA), in male rats. Anandamide (AEA) content was downregulated after repeated seizures, and pharmacological enhancement of AEA signaling rescued seizure-induced anxiety by restoring the tonic control of the eCB signaling over glutamatergic transmission. Moreover, AEA signaling augmentation also rescued the seizure-induced alterations of fear memory by restoring the phasic control of eCB signaling over GABAergic activity and plasticity in the BLA. These results indicate that modulation of AEA signaling represents a potential and promising target for the treatment of comorbid emotional dysfunction associated with epilepsy.SIGNIFICANCE STATEMENT Epilepsy is a heterogeneous neurologic disorder commonly associated with comorbid emotional alterations. However, the management of epilepsy is usually restricted to the control of seizures. The endocannabinoid (eCB) system, particularly anandamide (AEA) signaling, controls neuronal excitability and seizure expression and regulates emotional behavior. We found that repeated seizures cause an allostatic maladaptation of AEA signaling in the amygdala that drives emotional alterations. Boosting AEA signaling through inhibition of its degradative enzyme, fatty acid amide hydrolase (FAAH), restored both synaptic and behavioral alterations. FAAH inhibitors dampen seizure activity in animal models and are used in clinical studies to treat the negative consequences associated with stress. Thereby, they are accessible and can be clinically evaluated to treat both seizures and comorbid conditions associated with epilepsy.