Reflex seizures, traits, and epilepsies: from physiology to pathology

Child Neurology: Neurophysiologic and Anatomical Correlates in Startle Epilepsy: A Comprehensive SEEG Investigation for Successful Resective Surgery

Startle epilepsy, characterized by startle-provoked epileptic seizures, was historically recognized as one of the reflex epilepsies but currently lacks classification as a specific epileptic syndrome because of insufficient characterization. This study presents an institutional experience and review of relevant literature focusing on the neurophysiologic and anatomical aspects of startle epilepsy. We describe a pediatric patient with an underlying structural etiology of left frontal encephalomalacia who continued to experience disabling seizures despite multiple antiseizure medications and previous palliative surgery. A comprehensive presurgical evaluation using SEEG led to the resection of the left supplementary motor area and adjacent middle cingulate cortex, resulting in successful seizure remission. A literature review on the surgical treatment of startle epilepsy revealed consistent reports of successful seizure remission through neocortical resection of the supplementary motor area and/or cingulate region. This case study and literature review highlights startle epilepsy as a distinct form of epilepsy with identifiable neurophysiologic and anatomical characteristics. Our observations emphasize the potential of resective surgery as a viable treatment option for startle epilepsy and underscore the importance of neurophysiologic monitoring in guiding surgical interventions.

Clinical profiles and prognostic factors in reflex epilepsy: Insights from a Taiwanese cohort

PURPOSE

To investigate the clinical characteristics, treatment, and prognosis of patients with reflex epilepsies in Taiwan.

METHODS

Patients with reflex epilepsies (RE) induced by specific trigger factors from July 2000 to May 2024, were recruited at Chang Gung Memorial Hospital, Linkou, Taiwan. All patients had at least 12 months of follow-up. Demographic data, antiseizure medication (ASM) treatment, stimulus avoidance, and seizure outcome were analyzed. We further divided the patients into extrinsic and intrinsic RE groups based on the nature of stimuli. We also categorized them into ongoing seizure and seizure-free groups based on their seizure control. Fisher's exact test and Independent-Samples Mann-Whitney U Test were used to evaluate associations between clinical factors and prognosis. Multivariate logistic regression analysis was further carried out to determine the predictors of seizure outcomes.

RESULTS

In this study, 81 patients with reflex epilepsies (RE) were analyzed, focusing on those with extrinsic (photosensitive) and intrinsic (Mah-Jong-related) seizure triggers. Patients with extrinsic RE were significantly younger (mean age 40.4 years) than those with intrinsic RE (mean age 64.4 years, p < 0.001) and had a notably earlier onset of reflex seizures (21.9 years vs. 49.7 years, p < 0.001). A higher proportion of extrinsic RE patients experienced spontaneous seizures (98 %) compared to intrinsic RE (40 %). Abnormal EEG findings were more prevalent in the extrinsic group (94.1 %) than in the intrinsic group (66.7 %). Ninety-eight percent of patients with extrinsic RE were treated with antiseizure medications (ASMs), with an average of 2.2 ASMs per patient, compared to 73.3 % and 1.2 ASMs in patients with intrinsic RE. Furthermore, the rate of stimulus avoidance was significantly higher among those with intrinsic RE, at 43.3 % compared to 3.9 % in the extrinsic group (p < 0.001). Both groups achieved similar seizure-free outcomes (68.6 % in extrinsic vs. 63.3 % in intrinsic RE), but stimulus avoidance is independently associated with a reduced likelihood of ongoing seizures (p = 0.038), with an odds ratio (OR) of 0.110.

CONCLUSION

Intrinsic RE exhibited a later onset of spontaneous and reflex seizures than extrinsic RE. Avoidance of seizure triggers was more frequent in intrinsic RE and among seizure-free patients, suggesting that stimulus avoidance is crucial for better seizure control and prognosis. On the other hand, patients with extrinsic RE had a lower rate of trigger avoidance but were more likely to receive ASM treatment, suggesting ASM is crucial for managing seizures due to challenges in avoiding environmental triggers. Despite these differences, both groups achieved similar seizure-free outcomes, underscoring the necessity for tailored management strategies based on the type of reflex seizures.

Self-Induced Mania Methods and Motivations Reported in Online Forums: Observational Qualitative Study

BACKGROUND

In bipolar disorder (BD), mania may be self-induced by manipulation of specific precipitants, as reported in case studies. Another potential source of information on the self-induction of mania is the online postings of users with lived experience of mania.

OBJECTIVE

The primary aim of this study is to examine the range of methods used to self-induce mania or hypomania described by users of online forums with self-reported BD. Second, we summarize the motivations of users to engage in these behaviors.

METHODS

We conducted an observational study of online forum posts that discussed self-induction of mania or hypomania, either in the posters themselves or observed firsthand in others. Posts were identified using Google advanced search operators, then extracted and coded for content in NVivo (version 12 for Mac; QSR International). A total of 44 online forum threads were identified discussing self-induced mania (n=25) or hypomania (n=19). These forums contained 585 posts by 405 usernames, of which 126 usernames discussed methods for self-induction across 327 posts (number of methods per username: median 2, IQR 1-4; range 1-11).

RESULTS

In total, 36 methods were grouped by the authors. The most frequently reported were sleep reduction (n=50), caffeine (n=37), and cessation of medication (n=27). Twenty-six usernames reported their motivation to self-induce mania or hypomania; almost three-quarters (n=19) reported a desire to end a depressive episode. Almost a third of usernames (118/405) explicitly discouraged other forum users from self-inducing mania or hypomania.

CONCLUSIONS

Online forums provide an additional and valuable source of information about triggers for mania that may inform relapse prevention in BD. The online forum conversations investigated were generally responsible and included cautionary advice not to pursue these methods.

Interictal head-turning sign in patients with idiopathic generalized epilepsy during initial medical interview: A matched multicenter study

BACKGROUND

Utilizing interictal manifestations for the diagnosis of epilepsy is challenging. We investigated whether an interictal "head-turning sign," typically indicative of dependence on others observed in Alzheimer's disease, can act as a behavioral marker of idiopathic generalized epilepsy.

METHODS

This multicenter study examined 579 consecutive patients, with a mean age of 36.8 ± 20.4 years, who did not have an intellectual disability and had their first outpatient visit for epilepsy evaluation between 2019 and 2023. Patients were categorized into IGE, non-IGE epilepsy, non-epileptic, and psychiatric conditions based on their ultimate diagnostic outcomes to identify difference of the occurrence of the head-turning sign among them. Additionally, we extracted data from patients under the age of 40, specifically adolescents and young adults (AYA). Then we used propensity score matching to confirm the reproducibility of observed differences and to identify associated factors within the AYA age group.

RESULTS

The occurrence of the head-turning sign was significantly more prevalent in the IGE group compared to the non-IGE group (20.4 % vs. 2.2 %; P<0.0001) and non-epileptic group (20.4 % vs. 8.3 %; P=0.033). Following the matching, the head-turning sign was still evident in IGE relative to non-IGE patients (14.6 % vs. 4.5; P=0.004), yielding a 94 % specificity for IGE. IGE diagnosis (P<0.0001), myoclonic seizure (P<0.0001), being visited by a parent (P=0.017), and comorbidity with headache (P=0.021) were significantly associated with the head-turning sign. Multivariate analysis revealed that IGE (odds ratio: OR=2.80, P=0.028), attending with a parent (OR=2.92, P=0.029), and comorbidity with headache (OR=4.06, P=0.016) were independently associated with the head-turning sign.

CONCLUSIONS

We confirmed a substantial association between the interictal "head-turning sign" and IGE. This unique sign may reflect a tendency towards dependence on others in IGE, and may serve as a promising diagnostic auxiliary marker for identifying IGE in the AYA age group.

Disney to Pixar Transition Causing Epilepsy: A Case Report of Reflex Epilepsy

This case report describes a rare instance of reflex seizures in a 4-year-old boy with a complex medical history, including total anomalous pulmonary venous connection and developmental disabilities. The patient experienced seizures triggered exclusively by a specific visual stimulus: the transition scene from the Disney castle to the Pixar lamp in Disney-Pixar movies. Video electroencephalography (EEG) revealed biparasagittal rhythmic delta waves and diffuse slowing, suggesting parietal involvement and complex cortical processing. The findings highlight the individualized nature of reflex epilepsy and highlight the need for a nuanced understanding of specific seizure triggers. Effective management included avoiding the identified visual stimulus and adjusting medication based on the patient's response. This case emphasizes the intricate relationship between sensory processing and epileptogenic mechanisms, contributing to our knowledge of cortical excitability and guiding targeted treatment strategies for reflex seizures.

Timing Mechanisms for Circadian Seizures

For centuries, epileptic seizures have been noticed to recur with temporal regularity, suggesting that an underlying biological rhythm may play a crucial role in their timing. In this review, we propose to adopt the framework of chronobiology to study the circadian timing of seizures. We first review observations made on seizure timing in patients with epilepsy and animal models of the disorder. We then present the existing chronobiology paradigm to disentangle intertwined circadian and sleep-wake timing mechanisms. In the light of this framework, we review the existing evidence for specific timing mechanisms in specific epilepsy syndromes and highlight that current knowledge is far from sufficient. We propose that individual seizure chronotypes may result from an interplay between independent timing mechanisms. We conclude with a research agenda to help solve the urgency of ticking seizures.

Clinical Insights Into Eating-Induced Reflex Epilepsy: A Case Report of an Eight-Year-Old Girl

Eating epilepsy is a rare condition in children where seizures are triggered by the act of eating. An eight-year-old girl presented with seizures occurring primarily during mealtimes, characterized by a fixed gaze, jaw hypotonia, and impaired awareness. These seizures began at age seven, were initially uninvestigated, and progressively worsened over the year, reaching up to 20-30 episodes per meal. Diagnostic tests, including blood work, upper gastrointestinal endoscopy, psychiatric evaluation, and magnetic resonance imaging (MRI), were normal. The EEG showed generalized epileptiform activity, suggesting a seizure disorder, but the exact cause was unclear. After ruling out more common conditions with similar symptoms, such as gastroesophageal reflux disease, Sandifer syndrome, and psychogenic non-epileptic seizures, the diagnosis of reflex eating epilepsy was made in the end through a process of elimination, combining clinical features with EEG findings and through reviewing the literature. Treatment with oral sodium valproate monotherapy led to significant symptomatic improvement, reducing the frequency of seizures during meals.

Cold-Induced Reflex Epilepsy

This case report describes a woman cold-induced reflex seizures.

Long-term prognosis of patients with photosensitive idiopathic generalized epilepsy

OBJECTIVE

The long-term prognosis of photosensitive idiopathic generalized epilepsy (p-IGE) is generally considered favorable; however, its specific characteristics remain unclear. Our objective was to investigate the extended prognosis of p-IGE.

METHODS

We analyzed the demographics, clinical, and electroencephalographic (EEG) data of consecutive patients who were diagnosed as having p-IGE, who were under follow-up for a minimum of 10 years and exhibited a photoparoxysmal response (PPR) in their EEGs. Prognostic data, epilepsy course types, and electroclinical variables were compared using appropriate statistical methods.

RESULTS

The mean follow-up duration for 108 consecutive patients with p-IGE (74.1 % female) was 16.8 ± 6.5 years. The main syndromes within this cohort included juvenile myoclonic epilepsy (37 %), juvenile absence epilepsy (15.7 %), and epilepsy with eyelid myoclonia (EEM) (14.8 %). In terms of epilepsy course types, 27.8 % were in the relapse-remission group, and 13.9 % had never experienced remission. A low early remission rate (5.6 %) was evident, with the remaining half of the cohort categorized as the late remission group. Several significant poor prognostic factors were identified including self-induction, clinical symptoms accompanying PPR, asynchrony and focal findings in EEG discharges, a wide frequency range of PPR, the coexistence of three seizure types, the presence of accompanying focal seizure features, and a history of convulsive status epilepticus.

CONCLUSIONS

Our long-term follow-up study, conducted within a substantial p-IGE group, unveiled newly proposed course types within this epilepsy category and highlighted significant poor prognostic factors related to photosensitivity. These findings furnish valuable insights for precise prognosis counselling and effective management strategies for patients with p-IGE.

Video-electroencephalographic findings and clinical characteristics of bathing seizures in children

Objective

To explore the electroencephalogram (EEG) and clinical characteristics of childhood bathing epilepsy.

Methods

We conducted a prospective summary of the clinical data from 10 children with bathing epilepsy who were admitted to Hunan Children's Hospital from April 2019 to November 2023 and analyzed their EEGs and clinical characteristics.

Results

Our 10 patients included eight males and two females, with seizure-onset ages ranging from 4 months and 20 days to 14 months. Nine cases showed normal intellectual development, and one case manifested delayed development. The Video-EEG (VEEG) findings showed that nine cases exhibited normal background with no interictal epileptic discharge. The seizures were characterized by lip cyanosis, tachycardia or bradycardia, weakness, paleness, and loss of consciousness. Ictal EEG revealed rhythmic fast waves, spike waves, spike-slow waves, or slow and sharp-wave activity over the temporal region (eight cases) or the occipital and temporal regions (one case), finally evolving into a delta rhythm that lasted for 57-201 s. These children exhibited no seizures after discontinuing bathing and were not administered antiseizure medication. The interictal EEG of one case reflected mild slow background and focal interictal epileptic discharge; and her semiology was eyes gazing to right, with clonic movements of the right face and lips, lip cyanosis, bradycardia, and impaired consciousness. Ictal EEG showed spike-wave and spike-slow-wave rhythms over the left central, parietal, and temporal regions; these then spread to the left hemisphere, lasting for approximately 104 s. This patient did not exhibit bathing seizures after stopping her bathing but later experienced frequent spontaneous and drug-resistant seizures. The interictal EEG background slowed down, while focal epileptic discharge increased. Her intellectual development was significantly delayed, and a novel pathogenic mutation in the SMC1A gene, c.298+2T>C, was detected. She was diagnosed with developmental and epileptic encephalopathy.

Conclusion

A majority of children with bathing epilepsy in our study showed focal autonomic seizures accompanied by impaired consciousness. Stopping bathing could control the seizures and showed a good prognosis. A few infants manifested a poor prognosis, and we posit that bathing seizure rarely constitute the early manifestations of developmental and epileptic encephalopathy. VEEG findings and clinical features can also indicate the prognosis.

Idiopathic Generalized Epilepsy: Misunderstandings, Challenges, and Opportunities

The idiopathic generalized epilepsies (IGE) make up a fifth of all epilepsies, but <1% of epilepsy research. This skew reflects misperceptions: diagnosis is straightforward, pathophysiology is understood, seizures are easily controlled, epilepsy is outgrown, morbidity and mortality are low, and surgical interventions are impossible. Emerging evidence reveals that patients with IGE may go undiagnosed or misdiagnosed with focal epilepsy if EEG or semiology have asymmetric or focal features. Genetic, electrophysiologic, and neuroimaging studies provide insights into pathophysiology, including overlaps and differences from focal epilepsies. IGE can begin in adulthood and patients have chronic and drug-resistant seizures. Neuromodulatory interventions for drug-resistant IGE are emerging. Rates of psychiatric and other comorbidities, including sudden unexpected death in epilepsy, parallel those in focal epilepsy. IGE is an understudied spectrum for which our diagnostic sensitivity and specificity, scientific understanding, and therapies remain inadequate.

Intracortical functional connectivity dynamics induced by reflex seizures

Functional connectivity analysis is gaining more interest due to its promising clinical applications. To study network mechanisms underlying seizure termination and postictal depression, we explore dynamics of interhemispheric functional connectivity near the offset of focal and bilateral seizures in the experimental model of reflex audiogenic epilepsy. In the model, seizures and spreading depression are induced by sound stimulation of genetically predisposed rodents. We characterize temporal evolution of seizure-associated coupling dynamics in the frontoparietal cortex during late ictal, immediate postictal and interictal resting states, using two measures applied to local field potentials recorded in awake epileptic rats. Signals were analyzed with mean phase coherence index in delta (1-4 Hz), theta (4-10 Hz) beta (10-25 Hz) and gamma (25-50 Hz) frequency bands and mutual information function. The study shows that reflex seizures elicit highly dynamic changes in interhemispheric functional coupling with seizure-, region- and frequency-specific patterns of increased and decreased connectivity during late ictal and immediate postictal periods. Also, secondary generalization of recurrent seizures (kindling) is associated with pronounced alterations in resting-state functional connectivity - an early wideband decrease and a subsequent beta-gamma increase. The findings show that intracortical functional connectivity is dynamically modified in response to seizures on short and long timescales, suggesting the existence of activity-dependent plastic network alterations that may promote or prevent seizure propagation within the cortex and underlie postictal behavioral impairments.

A 6-Year-Old With Episodes of Hand-Waving and Loss of Attention

A 6-year-old girl was referred to pediatric neurology because of concerns about her behavior. Her mother had noticed episodes in which the girl would wave her hand in front of her face and lose awareness of her surroundings several times per day. These episodes usually occurred when she was outdoors and had caused the child to walk into objects and stop in traffic. The patient otherwise had no neurological deficits or cognitive impairment, and there was no family history of neuropsychiatric disorders. Although the patient was aware of her behavior, she could not explain why she performed these hand-waving motions. A neurological workup revealed that these behaviors were not complex stereotypies but rather a rare and unusual disorder. This case highlights the role of neurology in assessing complex motor behaviors and offers insight into when a practicing pediatrician should consider a neurological workup for complex stereotypies. [Pediatr Ann. 2023;52(8):e309-e312.].

Does seizure propagate within or across intrinsic brain networks? An intracranial EEG study

BACKGROUND

Understanding the spatiotemporal propagation profiles of seizures is crucial for the preoperative assessment of epilepsy patients. The present study aimed to investigate whether seizures exhibit propagation patterns that align with intrinsic networks (INs).

METHODS

A quantitative analysis was conducted to examine ictal fast activity (IFA). The Epileptogenicity Index (EI) was employed to assess the epileptogenicity, spectral features, and temporal characteristics of IFA. Intra-network and inter-network comparisons were made regarding the IFA-related metrics. Additionally, the metrics were correlated with Euclidean distance. Network connection maps were generated to visualize seizures originating from different INs, allowing for comparisons between distinct groups.

RESULTS

Data for 81 seizures in 43 subjects were captured using stereoelectroencephalography implantation. Three metrics were compared: EI, time involvement (TI), and energy ratio index (ERI). Intra-network channels exhibited higher EI, earlier involvement of IFA, and stronger high-frequency energy. These findings were further validated through subgroup analyses stratified by neuropathology, seizure type, and seizure origination lobe. Correlation analyses revealed a negative association between distance and both EI and ERI, while distance exhibited a positive correlation with TI. Seizures originating from different INs exhibited varying propagation characteristics.

CONCLUSIONS

The study findings highlight the dominant role of intra-network dynamics over inter-network during seizure propagation. These results contribute to our understanding of seizure dynamics and their relationship with INs.

Non-invasive sensory neuromodulation in epilepsy: Updates and future perspectives

Epilepsy, one of the most common neurological disorders, often is not well controlled by current pharmacological and surgical treatments. Sensory neuromodulation, including multi-sensory stimulation, auditory stimulation, olfactory stimulation, is a kind of novel noninvasive mind-body intervention and receives continued attention as complementary safe treatment of epilepsy. In this review, we summarize the recent advances of sensory neuromodulation, including enriched environment therapy, music therapy, olfactory therapy, other mind-body interventions, for the treatment of epilepsy based on the evidence from both clinical and preclinical studies. We also discuss their possible anti-epileptic mechanisms on neural circuit level and propose perspectives on possible research directions for future studies.

Telemedicine for Individuals with epilepsy: Recommendations from International League Against Epilepsy Telemedicine Task Force

Worldwide, People with Epilepsy (PWE) are confronted with several barriers to face-to-face consultations. These obstacles hamper appropriate clinical follow-up and also increase the treatment gap for Epilepsy. Telemedicine holds the potential to enhance management as follow-up visits for PWE are focused on more on clinical history and counselling rather than physical examination. Besides consultation, telemedicine can also be used for remote EEG diagnostics and tele-neuropsychology assessments. In this article, the Telemedicine Task Force of the International League Against Epilepsy (ILAE) outlines recommendations regarding optimal practice in utilizing in the management of individuals with epilepsy. We formulated recommendations for minimum technical requirements, preparing for the first tele-consultation and the specificities for follow-up consultations. Special considerations are necessary for specific populations, including paediatric patients, patients who are not conversant with tele-medicine and those with intellectual disability. Telemedicine for individuals with epilepsy should be vigorously promoted with the aim of improving the quality of care and ultimately reduce the wide clinician access related treatment gap across several regions of the globe.

Towel induced reflex seizures

Reflex epilepsies are a unique and heterogeneous group of epilepsies characterized by recurrent seizure activity evoked by a specific external sensory stimulus or internal cognitive process. Reflex seizures can be part of other epilepsy syndromes including focal and generalized syndromes and have a growing spectrum of presentations. We report a further subtype of reflex seizures associated with towel exposure. We give an account of a case of drug-refractory focal epilepsy admitted to the Epilepsy Monitoring Unit for presurgical assessment with 50% of seizures triggered in response to the touch, feel, smell and thoughts around towels. We reviewed the literature regarding the broad phenotype of reflex epilepsies and seizures.

Psychophysiological interaction analysis for the detection of stimulus-specific networks in reflex epilepsy

We report detailed functional MRI (fMRI) analyses in a patient with reflex seizures elicited by driving along a specific rural crossroad or by watching a video thereof. Semiology consisted of epigastric aura, followed by a sensory seizure of the left hand and sporadic automotor seizures. The right amygdala-region (rh-amygdala) was surgically and electroclinically confirmed as the epileptogenic zone. Presurgical task-fMRI was performed, during which videos of the driving along that specific crossroad (IC), of another crossroad (NC) or noise were presented. Independent component analysis was conducted, and one component was used to aid in selection of a seed region within the rh-amygdala for subsequent psychophysiological interaction analysis (PPI). Here, the following regions showed stronger connectivity with the rh-amygdala seed during the IC condition compared to NC: right > left visual cortex, bilateral insulae, and right secondary somatosensory cortex (S2), potentially explaining epigastric aura and left somatosensory seizure semiology. Contralateral analyses did not reproduce these results. Overall, the ictogenic stimulus elicited enhanced connectivity of the epileptogenic rh-amygdala with visual cortex and further regions of potential seizure spread (S2, insula) as a putative mechanism of ictogenesis. Our results highlight the potential of PPI in the analysis of stimulus-dependent networks in patients with reflex epilepsies to gain insight into seizure generation.

Respiratory alkalosis provokes spike-wave discharges in seizure-prone rats

Hyperventilation reliably provokes seizures in patients diagnosed with absence epilepsy. Despite this predictable patient response, the mechanisms that enable hyperventilation to powerfully activate absence seizure-generating circuits remain entirely unknown. By utilizing gas exchange manipulations and optogenetics in the WAG/Rij rat, an established rodent model of absence epilepsy, we demonstrate that absence seizures are highly sensitive to arterial carbon dioxide, suggesting that seizure-generating circuits are sensitive to pH. Moreover, hyperventilation consistently activated neurons within the intralaminar nuclei of the thalamus, a structure implicated in seizure generation. We show that intralaminar thalamus also contains pH-sensitive neurons. Collectively, these observations suggest that hyperventilation activates pH-sensitive neurons of the intralaminar nuclei to provoke absence seizures.

Minimum standards for inpatient long-term video-EEG monitoring: A clinical practice guideline of the international league against epilepsy and international federation of clinical neurophysiology

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long-term video-electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. We found limited high-level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events (see Table S1). For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long-term outcome effects of LTVEM and establish its clinical utility.

Minimum standards for inpatient long-term video-electroencephalographic monitoring: A clinical practice guideline of the International League Against Epilepsy and International Federation of Clinical Neurophysiology

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long-term video-electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) statement. We found limited high-level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events. For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long-term outcome effects of LTVEM and to establish its clinical utility.

Loss of glutamate transporter eaat2a leads to aberrant neuronal excitability, recurrent epileptic seizures, and basal hypoactivity

Astroglial excitatory amino acid transporter 2 (EAAT2, GLT‐1, and SLC1A2) regulates the duration and extent of neuronal excitation by removing glutamate from the synaptic cleft. Hence, an impairment in EAAT2 function could lead to an imbalanced brain network excitability. Here, we investigated the functional alterations of neuronal and astroglial networks associated with the loss of function in the astroglia predominant eaat2a gene in zebrafish. We observed that eaat2a^−/− mutant zebrafish larvae display recurrent spontaneous and light‐induced seizures in neurons and astroglia, which coincide with an abrupt increase in extracellular glutamate levels. In stark contrast to this hyperexcitability, basal neuronal and astroglial activity was surprisingly reduced in eaat2a^−/− mutant animals, which manifested in decreased overall locomotion. Our results reveal an essential and mechanistic contribution of EAAT2a in balancing brain excitability, and its direct link to epileptic seizures.

Pattern-sensitive patients with epilepsy use uncomfortable visual stimuli to self-induce seizures

Sensory stimuli can induce seizures in patients with epilepsy and predisposed subjects. Visual stimuli are the most common triggers, provoking seizures through an abnormal response to light or pattern. Sensitive patients may intentionally provoke their seizures through visual stimuli. Self-induction methods are widely described in photo-sensitive patients, while there are only a few reports of those who are pattern-sensitive. We analyzed 73 images of environmental visual triggers collected from 14 pattern-sensitive patients with self-induced seizures. The images were categorized according to their topics: 29 Objects (43%); 19 Patterns (28%); 15 External scenes (22%); 4 TV or computer screens (6%). Six photos were of poor quality and were excluded from analysis. Images were analyzed by an algorithm that calculated the degree to which the Fourier amplitude spectrum differed from that in images from nature. The algorithm has been shown to predict discomfort in healthy observers. The algorithm identified thirty-one images (46%) as "uncomfortable". There were significant differences between groups of images (ANOVA p = .0036; Chi2 p < .0279), with higher values of difference from nature in the images classified as "Objects" (mean 6,81E+11; SD 6,72E+11; n.17, 59%) and "Pattern" (mean 9,05E+11; SD 6,86E+11; n.14, 74%). During the semi-structured face-to-face interviews, all patients described the visual triggers as 'uncomfortable'; the appearance of enjoyable visual epileptic symptoms (especially multi-colored hallucinations) transformed uncomfortable images into pleasant stimuli. Patients considered self-induction as the simplest and most effective way to overcome stressful situations, suggesting that self-inducing pattern-sensitive patients often use uncomfortable visual stimuli to trigger their seizures. Among the reasons for the self-inducing behavior, the accidental discovery of pleasurable epileptic symptoms related to these "uncomfortable" visual stimuli should be considered.

Food intake precipitates seizures in temporal lobe epilepsy

Various factors have been considered as potential seizure precipitants. We here assessed the temporal association of food intake and seizure occurrence, and characteristics of seizures and epilepsy syndromes involved. 596 seizures from 100 consecutive patients undergoing long-term video-EEG monitoring were analyzed. Preictal periods of 60 min were assessed as to the occurrence of food intake, and latencies between food intake and seizure onset were analyzed. Seizures of temporal origin were highly significantly more frequently preceded by food intake compared to those of extratemporal origin; and were associated with shorter food intake-seizure latency. Seizure precipitation by food intake showed male predominance. Shorter food intake-seizure latency was associated with less severe seizures and less frequent contralateral spread of epileptic discharges. We here show for the first time that not only in specific rare reflex epilepsies but in the most frequent form of focal epilepsy, temporal lobe epilepsy, seizures are significantly precipitated by food intake. Seizure occurrence was increased over a period of up to one hour following food intake, and remained more localized in terms of both ictal EEG spread and as reflected by seizure severity. This finding supports the emerging concepts of ictogenesis, implying a continuum between reflex and spontaneous seizures-instead a dichotomy between them.

Reflex Epilepsy

Reflex seizures (RS) are epileptic events that are objectively and consistently elicited in response to a specific afferent stimulus or by an activity of the patient. The specific stimulus can be a variety of heterogenous intrinsic or extrinsic factors, ranging from the simple to the complex, such as flashing lights or reading a book. These seizures can take a variety of forms, comprising either general or focal onset, with or without secondary generalization. Reflex epilepsies (RE) are classified as a specific syndrome in which all epileptic seizures are precipitated by sensory stimuli. The few designated RE include idiopathic photosensitive occipital lobe epilepsy, other visual sensitive epilepsies, primary reading epilepsy, and startle epilepsy. RS that occurs within other focal or generalized epilepsy syndromes that are associated with distinct spontaneous seizures are classified by the overarching seizure type. Most patients experience spontaneous seizures along with their provoked events. RS originate from stimulation of functional anatomic networks normally functioning for physiological activities, that overlap or coincide with regions of cortical hyperexcitability. Generalized RS typically occur within the setting of IGEs and should be considered as focal seizures with quick secondary generalization via cortico-cortical or cortico-reticular pathways. In aggregate, activation of a critical neuronal mass, supported and sustained by cortico-subcortical and thalamocortical pathways eventually result in a seizure. Treatment includes antiseizure medication, commonly valproate or levetiracetam, along with lifestyle modifications, and when amenable, surgical intervention. High clinical suspicion and careful history taking must be employed in all epilepsy patients to identify reflex triggers.

Clinical and Genetic Features in Patients With Reflex Bathing Epilepsy

Objective

To describe the clinical and genetic findings in a cohort of individuals with bathing epilepsy, a rare form of reflex epilepsy.

Methods

We investigated by Sanger and targeted resequencing the SYN1 gene in 12 individuals from 10 different families presenting with seizures triggered primarily by bathing or showering. An additional 12 individuals with hot-water epilepsy were also screened.

Results

In all families with bathing epilepsy, we identified 8 distinct pathogenic or likely pathogenic variants and 2 variants of unknown significance in SYN1, 9 of which are novel. Conversely, none of the individuals with hot-water epilepsy displayed SYN1 variants. In mutated individuals, seizures were typically triggered by showering or bathing regardless of the water temperature. Additional triggers included fingernail clipping, haircutting, or watching someone take a shower. Unprovoked seizures and a variable degree of developmental delay were also common.

Conclusion

Bathing epilepsy is genetically distinct reflex epilepsy caused mainly by SYN1 mutations.

Rapidly spreading seizures arise from large-scale functional brain networks in focal epilepsy

It remains unclear whether epileptogenic networks in focal epilepsy develop on physiological networks. This work aimed to explore the association between the rapid spread of ictal fast activity (IFA), a proposed biomarker for epileptogenic networks, and the functional connectivity or networks of healthy subjects. We reviewed 45 patients with focal epilepsy who underwent electrocorticographic (ECoG) recordings to identify the patients showing the rapid spread of IFA. IFA power was quantified as normalized beta-gamma band power. Using published resting-state functional magnetic resonance imaging databases, we estimated resting-state functional connectivity of healthy subjects (RSFC-HS) and resting-state networks of healthy subjects (RSNs-HS) at the locations corresponding to the patients' electrodes. We predicted the IFA power of each electrode based on RSFC-HS between electrode locations (RSFC-HS-based prediction) using a recently developed method, termed activity flow mapping. RSNs-HS were identified using seed-based and atlas-based methods. We compared IFA power with RSFC-HS-based prediction or RSNs-HS using non-parametric correlation coefficients. RSFC and seed-based RSNs of each patient (RSFC-PT and seed-based RSNs-PT) were also estimated using interictal ECoG data and compared with IFA power in the same way as RSFC-HS and seed-based RSNs-HS. Spatial autocorrelation-preserving randomization tests were performed for significance testing. Nine patients met the inclusion criteria. None of the patients had reflex seizures. Six patients showed pathological evidence of a structural etiology. In total, we analyzed 49 seizures (2-13 seizures per patient). We observed significant correlations between IFA power and RSFC-HS-based prediction, seed-based RSNs-HS, or atlas-based RSNs-HS in 28 (57.1%), 21 (42.9%), and 28 (57.1%) seizures, respectively. Thirty-two (65.3%) seizures showed a significant correlation with either seed-based or atlas-based RSNs-HS, but this ratio varied across patients: 27 (93.1%) of 29 seizures in six patients correlated with either of them. Among atlas-based RSNs-HS, correlated RSNs-HS with IFA power included the default mode, control, dorsal attention, somatomotor, and temporal-parietal networks. We could not obtain RSFC-PT and RSNs-PT in one patient due to frequent interictal epileptiform discharges. In the remaining eight patients, most of the seizures showed significant correlations between IFA power and RSFC-PT-based prediction or seed-based RSNs-PT. Our study provides evidence that the rapid spread of IFA in focal epilepsy can arise from physiological RSNs. This finding suggests an overlap between epileptogenic and functional networks, which may explain why functional networks in patients with focal epilepsy frequently disrupt.

What's behind drawing for an artist with left temporal lobe epilepsy? A multimodal neurophysiological study

There are few studies in literature reporting drawing as a strong trigger of praxis-induced focal seizures. The aim of the present case report was describing a case of focal epilepsy with praxis induced EEG activation, due to a cavernoma, in the left middle anterior temporal lobe by using a multimodal approach. We combined video-EEG, showing that drawing increased a sustained monomorphic delta activity localized on left anterior temporal region (F7-T1a), diffusing to the vertex (Fz) and the fronto-polar electrodes (F3), with DTI data, showing that the left uncinate fasciculus, connecting the temporal pole to the orbitofrontal cortex, significantly differed from controls. fMRI confirmed that drawing increased activation in these areas. The congruence between findings supports the role of the left uncinated fasciculus linking the temporal lobe to the orbitofrontal cortex in the present focal epilepsy mainly facilitated by drawing.

Case Report: A Case of Eyelid Myoclonic Status With Tonic-Clonic Seizure and Literature Review

Eyelid myoclonus with or without absence epilepsy is a rare and usually misdiagnosed disease in the neurology department. It is an idiopathic general epileptic syndrome, the onset period is 6-8 years, and is more common in girls. It is characterized by rapid abnormal eye blinking, accompanied by upward rolling of the eye and slight backward movement of the head, with eye closure sensitivity and photosensitivity. The seizure is frequent and short, dozens or even hundreds of times a day; a small number of patients may have eyelid myoclonus status. We report a patient who visits the hospital for the first time with eyelid myoclonic problem; the patient continued to wink the eyes, eye rolled up, and backward movement of the head, accompanied by impairment of consciousness. Video electroencephalography (VEEG) suggests continued spike slow-wave, polyspike slow-wave. After the patient had 2, 4, 6, 8, 10, 12, and 14 Hz of intermittent photic stimulation (IPS), her seizures and epileptic discharges reduced or stopped. Seven min after giving stimulation at 20 Hz, the child developed an occipital-initiated tonic-clonic seizure, which demonstrated that after sufficient IPS stimulation, the occiput cortex became excited and initiated a brain network, leading to diffuse brain discharge and tonic-clonic seizures. At 1 h after onset, the child developed a nonconvulsive state, with impairment of consciousness despite no eyelid myoclonic movements, and VEEG suggested a large number of epileptic discharges. After 10 min of administrating midazolam, the patient's EEG immediately became normal, and the patient regained consciousness. Therefore, this paper presents an eyelid myoclonus status patient with occipital origin seizure, we recorded the whole course of the disease and the treatment effect, and reviewed the literature accordingly.

Is Covid-19 lockdown related to an increase of accesses for seizures in the emergency department? An observational analysis of a paediatric cohort in the Southern Italy

BACKGROUND

The World Health Organization (WHO) declared a global pandemic of Covid-19 on 11 March 2020. The lockdown caused a lifestyle changes: an increase in the use of mobile media devices (MMDs), sleep and psychiatric disorders, incorrect habits regarding food and physical activities. We investigate prevalence of admission for seizures at our emergency department (ED), during Italian lockdown, comparing with that of the same period of the previous year (2019), and the relationship with some lifestyle changes.

METHODS

In this observational study, patients (4-14 years) with seizures that accessed at our ED, during Italian lockdown, were eligible. Non-epileptic events and febrile seizures were excluded. We describe two groups: patients with new-onset seizures and not. Moreover, a questionnaire concerning use of MMDs and sleep habits was administered.

RESULTS

Fifty-seven patients were included; median age 8.03 years. Considering only paediatric medical emergencies, the prevalence of accesses for seizures was 2.6% (CI 95% 0.020-0.034), while the incidence was 0.94% (CI 95% 0.006-0.0149). There was a statistically significant difference with prevalence of previous years, χ² 102.21 (p = 0.0001). We also reported a difference in daily screen time (DST) (p = 0.001) and total sleep time (TST) (p = 0.045), in all population, between period pre- and during lockdown. A negative correlation between DST and seizures latency (Spearman's ρ -0.426, p = 0.038) was found. In the two groups, the results were partially overlapping.

CONCLUSIONS

During lockdown period, we assisted to an increase of accesses for seizures. It is conceivable that a sleep time change and/or higher MMD use could act as triggers for seizures.

Local Sleep Slow-Wave Activity Colocalizes With the Ictal Symptomatogenic Zone in a Patient With Reflex Epilepsy: A High-Density EEG Study

Background: Slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep reflects synaptic potentiation during preceding wakefulness. Epileptic activity may induce increases in state-dependent SWA in human brains, therefore, localization of SWA may prove useful in the presurgical workup of epileptic patients. We analyzed high-density electroencephalography (HDEEG) data across vigilance states from a reflex epilepsy patient with a clearly localizable ictal symptomatogenic zone to provide a proof-of-concept for the testability of this hypothesis.

Methods: Overnight HDEEG recordings were obtained in the patient during REM sleep, NREM sleep, wakefulness, and during a right facial motor seizure then compared to 10 controls. After preprocessing, SWA (i.e., delta power; 1–4 Hz) was calculated at each channel. Scalp level and source reconstruction analyses were computed. We assessed for statistical differences in maximum SWA between the patient and controls within REM sleep, NREM sleep, wakefulness, and seizure. Then, we completed an identical statistical comparison after first subtracting intrasubject REM sleep SWA from that of NREM sleep, wakefulness, and seizure SWA.

Results: The topographical analysis revealed greater left hemispheric SWA in the patient vs. controls in all vigilance states except REM sleep (which showed a right hemispheric maximum). Source space analysis revealed increased SWA in the left inferior frontal cortex during NREM sleep and wakefulness. Ictal data displayed poor source-space localization. Comparing each state to REM sleep enhanced localization accuracy; the most clearly localizing results were observed when subtracting REM sleep from wakefulness.

Conclusion: State-dependent SWA during NREM sleep and wakefulness may help to identify aspects of the potential epileptogenic zone. Future work in larger cohorts may assess the clinical value of sleep SWA to help presurgical planning.

Cortical-Subcortical morphometric signature of hot water epilepsy patients

BACKGROUND

Cortical and subcortical grey matter (GM) morphometric changes have been demonstrated Temporal Lobe Epilepsy (TLE) or Idiopathic Generalized Epilepsies (IGE). Hot Water Epilepsy (HWE) has not hitherto been studied in these perspectives.

PURPOSE

To investigate the cortical and subcortical grey matter in subjects with HWE in terms of thickness, volume, and surface area using Surface-Based Morphometry (SBM). To assess relationships of SBM-derived metrics with clinical variables.

MATERIALS AND METHODS

Ninety-nine people with HWE and 50 age-matched healthy controls underwent high resolution volumetric MRI brain. These were processed with FreeSurfer to obtain SBM parameters i:e cortical thickness, cortical volume, and Cortical surface area. Volumes of seven subcortical GM structures (hippocampus, globus pallidus, nucleus ambiguous(NA), caudate nucleus, putamen, thalamus, and amygdala) were computed. Intergroup morphometric differences and their correlation with epilepsy-specific clinical variables were calculated.

RESULTS

SBM revealed a global reduction in bihemispheric cortical thickness and left hemispheric cortical volume. Besides, a regional difference in the morphometric measures was noted in temporo-limbic, parietal, pre-cuneus, and the cingulate region. Reduced volume of thalami and left caudate alongside an increased volume of the bilateral amygdala, bilateral nucleus ambiguous (NA), right caudate, and putamen was the other cardinal observation.

CONCLUSION

HWE subjects show alterations in the morphometry of the cortical ribbon and the subcortical grey matter. The temporal semiology, 'reflex nature' pathophysiology correlates involvement of temporo-limbic structures/somatosensory cortex, while the involvement of structures like pre-cuneus, posterior cingulate, and frontal regions are in agreement with functional networks related loss of awareness. That bilateral amygdala swelling occurs in HWE is a novel observation and may signal that it could be a distinct variant of Mesial TLE.

How are results of EEG activation procedures associated with patient perception of seizure provocative factors? A single-center cross-sectional pilot study

PURPOSE

The purpose of this study was to examine the relationship between subjectively perceived seizure provocative factors or inhibitors and objectively recorded changes in epileptiform activity (EA) during EEG activation procedures.

MATERIAL AND METHODS

Consenting epilepsy patients (≥18 years old) were asked to complete a questionnaire by indicating whether items on a list provoke, inhibit or have no effect on their seizures. A scalp EEG was recorded afterwards to evaluate baseline epileptiform activity and its change (increase/decrease in frequency) during a set of activation procedures. These included hyperventilation, intermittent photic stimulation (IPS), eye-closing/eye-opening, tasks of reading aloud in a native and a foreign language, solving a Rubik's cube and crossing-out letters. We used correlation and multiple regression analysis to search for associations between the sum of self-reported provocative/inhibiting items and changes in EA.

RESULTS

Of the 90 patients recruited 75 (83.3%) indicated at least one seizure provocative factor. Sleep deprivation, emotional stress, negative emotions and alcohol use were most frequently selected as provoking seizures. Positive feelings, focused thinking, mental calculation and exercising were the most predominant seizure inhibitors. EEG data revealed a weak, but statistically significant correlation with the sum of items in distinct questionnaire groups (0.20 ≤ Spearman's ρ ≤ 0.39). Sensory stimuli (olfactory, gustatory, auditory and visual), cognitive phenomena (thoughts and feelings) and substance use were found to be significantly correlated with EEG results by being self-reported as both provoking and inhibiting seizures. A statistically significant relationship was also found between the increase in EA while reading aloud in a native language and the number of physiological states (sleep deprivation, stress etc.) indicated as provoking seizures (Spearman's ρ = 0.320, P = 0.005). A suitable stepwise multiple regression model was feasible for this finding (F(3, 71) = 7.396, P < 0.001, adjusted R squared = 0.206) with the additional inclusion of EA change during IPS and epilepsy type as explanatory variables.

CONCLUSION

Our pilot study indicates that there is a previously non-explored association between patients' self-perception of seizure provocative/inhibiting factors and objectively recorded changes in epileptiform activity during activation EEGs. Distinct EEG tests might be useful in activating ictogenic networks that are sensitive to indirect influence by hormonal, emotional or diurnally variable factors.

Location-specific reflex epilepsy: a novel reflex epilepsy phenotype

Reflex epilepsies are rare syndromes where seizures are triggered by particular stimuli or activities that may be motor, sensory or cognitive in nature. Triggers are diverse, may be extrinsic or intrinsic in nature and heterogeneous phenotypes have been described over the years. We give an account of a case of location-specific reflex epilepsy which we suggest is a novel reflex epilepsy phenotype relating to higher cortical function (HCF), and review the literature in relation to features of HCF reflex epilepsies described to date.

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Reflex seizures occur in a range of epilepsy syndromes.

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We describe a novel phenotype of location-specific reflex epilepsy associated with focal electrographic discharges.

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Higher cortical processes relating to being present in a particular location could serve as a trigger in reflex epilepsy.

Drug Treatment of Progressive Myoclonic Epilepsy

The progressive myoclonic epilepsies (PMEs) represent a rare but devastating group of syndromes characterized by epileptic myoclonus, typically action-induced seizures, neurological regression, medically refractory epilepsy, and a variety of other signs and symptoms depending on the specific syndrome. Most of the PMEs begin in children who are developing as expected, with the onset of the disorder heralded by myoclonic and other seizure types. The conditions are considerably heterogenous, but medical intractability to epilepsy, particularly myoclonic seizures, is a core feature. With the increasing use of molecular genetic techniques, mutations and their abnormal protein products are being delineated, providing a basis for disease-based therapy. However, genetic and enzyme replacement or substrate removal are in the nascent stage, and the primary therapy is through antiepileptic drugs. Epilepsy in children with progressive myoclonic seizures is notoriously difficult to treat. The disorder is rare, so few double-blinded, placebo-controlled trials have been conducted in PME, and drugs are chosen based on small open-label trials or extrapolation of data from drug trials of other syndromes with myoclonic seizures. This review discusses the major PME syndromes and their neurogenetic basis, pathophysiological underpinning, electroencephalographic features, and currently available treatments.

Reflex epileptic features in patients with focal epilepsy of unknown cause

OBJECTIVES

There is a gap of knowledge regarding reflex seizures in patients with focal epilepsy of unknown cause (FEUC). We aimed to evaluate the prevalence, demographic and clinical characteristics of reflex seizures in patients with FEUC to provide an insight to the underlying ictogenic mechanisms and to draw attention to this important but under-investigated topic.

PATIENTS AND METHODS

After carefully questioning for reflex triggers, 186 patients diagnosed according to ILAE criteria and followed-up for a minimum of 5 years were included. The demographic and clinical properties as well as electrophysiological and neuroimaging data of these patients were reevaluated and compared to the patients without reflex seizures.

RESULTS

The reflex seizure rate was 6.5 % in patients with FEUC. Patients with reflex features had lower monotherapy rates (p = 0.005) and higher major depression rates (p = 0.001) than patients without reflex features. The distribution of the patients according to their reflex triggers were as follows: hot-water induced (n = 3, 25 %), photosensitive (n = 2, 16.7 %), eating- induced (n = 2, 16.7 %), musicogenic (n = 2, 16.7 %), startle induced (n = 2, 16.7 %) and both musicogenic and startle type (n = 1, 8.3 %) respectively. The drug resistance rate of patients with reflex seizures was 25 % (n = 3). One patient with drug resistant reflex seizures showed benefit from epilepsy surgery and became seizure-free during last 3 years of follow-up.

CONCLUSION

A careful and thoroughly history taking specifically questioning and focusing on seizure inducing factors in patients with FEUC is needed to confirm the presence of reflex seizures in patients with FEUC, who had higher rates of polytherapy and major depression. Elaborative evaluation of reflex features in FEUC might contribute to effective seizure control, ensure new therapeutic approaches, enlighten the obscurity and the resulting anxiety of having a diagnosis of FEUC in epilepsy patients.

A rat model of somatosensory-evoked reflex seizures induced by peripheral stimulation

OBJECTIVE

We introduce a novel animal model of somatosensory stimulation-induced reflex seizures which generates focal seizures without causing damage to the brain.

METHODS

Specifically, we electrically stimulated digits or forepaws of adult rats sedated with dexmedetomidine while imaging cerebral blood volume and recording neurophysiological activity in cortical area S1FL. For the recordings, we either inserted a linear probe into the D3 digit representation or we performed surface electrocorticography (ECoG) recordings.

RESULTS

Peripheral stimulation of a digit or the forepaw elicited seizures that were followed by a refractory period with decreased neuronal activity, or another seizure or normal response. LFP amplitudes in response to electrical pulses during the seizures (0.28 ± 0.03 mV) were higher than during normal evoked responses (0.25 ± 0.05 mV) and refractory periods (0.2 ± 0.08 mV). Seizures generated during the stimulation period showed prolonged after-discharges that were sustained for 20.9 ± 1.9 s following the cessation of the stimulus. High-frequency oscillations were observed prior to and during the seizures, with amplitudes higher than those associated with normal evoked responses. The seizures were initially focal. Optical imaging of the cerebral blood volume response showed that they propagated from the onset zone to adjacent cortical areas, beyond the S1FL representation of the stimulated digit or forepaw. The spatial extent during seizures was on average 1.74 times larger during the stimulation and 4.1 times following its cessation relative to normal evoked responses. Seizures were recorded not only by probes inserted into cortex but also with ECoG arrays (24.1 ± 5.8 seizures per rat) placed over the dura matter, indicating that the seizures were not induced by damage caused by inserting the probes to the cortex. Stimulation of the forepaw elicited more seizures (18.8 ± 8.5 seizures per rat) than stimulation of a digit (1.7 ± 0.7). Unlike rats sedated with dexmedetomidine, rats anesthetized with urethane showed no seizures, indicating that the seizures may depend on the use of the mild sedative dexmedetomidine.

SIGNIFICANCE

Our proposed animal model generates seizures induced by electrical sensory stimulation free of artifacts and brain damage. It can be used for studying the mechanisms underlying the generation and propagation of reflex seizures and for evaluating antiepileptic drugs.

Affect-induced reflex seizures (AIRS): A case series based on a systematic literature review

Seizures are commonly thought to occur in a spontaneous, unpredictable manner. However, it is well-established that a subset of patients with epilepsy can experience reflex seizures that are consistently elicited by a specific stimulus. While various forms of reflex epilepsy have been documented in the literature, acute affective states have not been commonly described as a potential reflex seizure trigger. We performed a systematic literature review to determine if acute emotional states can trigger reflex seizures. We included any case in which reflex seizures repeatedly occurred in response to a patient-specific stimulus that was reported as emotionally relevant by the authors. This yielded our case series of ten patients who have been described to have reflex seizures in response to emotional stimuli. We characterized features of these cases including the following: age, gender, developmental and psychiatric history, seizure semiology and duration, emotional triggers, other reflex triggers, relationship between reflex triggers and seizures, investigations, localization, final diagnosis, treatment, and outcome. Considerable variability was found between cases. A trend toward limbic seizure semiology with psychic aura originating in networks involved in emotional processing was noted, with temporal lobe epilepsy being the most common, although without clear laterality or gender predominance. In addition, the report of a significant life stressor occurring at epilepsy onset in three of ten patients as well as the initial suspicion that reflex epileptic seizures were psychogenic in three cases both emphasize the role of electroencephalography in assessment of such presentations to avoid missing a diagnosis of epilepsy. Findings from these ten cases suggest that a patient-specific affective stimulus may trigger reflex seizures in a subset of patients, and that this could be underrecognized or mislabeled as nonepileptic. We encourage future studies with larger numbers to further characterize this phenomenon. Insights gained may enhance our understanding of seizure localization and bear potential treatment implications.

Outgrowing seizures in Childhood Absence Epilepsy: time delays and bistability

We formulate a conductance-based model for a 3-neuron motif associated with Childhood Absence Epilepsy (CAE). The motif consists of neurons from the thalamic relay (TC) and reticular nuclei (RT) and the cortex (CT). We focus on a genetic defect common to the mouse homolog of CAE which is associated with loss of GABA_A receptors on the TC neuron, and the fact that myelination of axons as children age can increase the conduction velocity between neurons. We show the combination of low GABA_A mediated inhibition of TC neurons and the long corticothalamic loop delay gives rise to a variety of complex dynamics in the motif, including bistability. This bistability disappears as the corticothalamic conduction delay shortens even though GABA_A activity remains impaired. Thus the combination of deficient GABA_A activity and changing axonal myelination in the corticothalamic loop may be sufficient to account for the clinical course of CAE.

Influence of hippocampal low-frequency stimulation on GABAA R α1, ICER and BNDF expression level in brain tissues of amygdala-kindled drug-resistant temporal lobe epileptic rats

This study investigated the therapeutic effect of hippocampal low-frequency stimulation (Hip-LFS) and its influence on the type A γ-aminobutyric acid receptor α1 subunit (GABA_A R α1 subunit), inducible cAMP early repressor (ICER) and brain-derived neurotrophic factors (BNDF). The model of epilepsy was induced by chronic electrical stimulation in amygdala. Drug-resistant and drug-sensitive epileptic rats were selected by testing their seizure response to phenytoin and phenobarbital. The changes of GABA_A R α1 subunit, ICER and BDNF expression were detected via immunohistochemistry and western blot. The expression levels of ICER and BDNF were increased remarkably but the GABA_A R α1 subunit decreased significantly in the drug-resistant epileptic rats. However, the expression levels of ICER, BDNF were decreased and the expression of the GABA_A R α1 subunit increased significantly in the drug-resistant epileptic rats after two weeks of Hip-LFS. Meanwhile, the seizure degree was reduced and the electroencephalograms were improved. The present study demonstrated thatincreased ICER and BDNF might be associated with the development of drug-resistance. The effect of Hip-LFS in the treatment of drug-resistant epileptic rats might be associated with increasing the levels of the ICER and the BDNF.