Do reflex seizures and spontaneous seizures form a continuum? - triggering factors and possible common mechanisms

Influence of weather regime and local geomagnetic activity on the occurrence of epileptic seizures

Epilepsy is a common neurologic disease and presents a major public health problem. Patients with epilepsy have unexpected occurrence of seizures with many triggered by existing triggering factors such as alcohol, stress etc. Other potential triggers include certain weather or atmospheric parameters and local geomagnetic activity. We have analyzed the impact of atmospheric parameters grouped in 6 grouped weather types or weather regimes and the local geomagnetic activity through the K - index. In the prospective study, we analyzed a total of 431 seizures over a 17-month period. In the results obtained, we found that the most severely common weather regime grouped type of weather was radiation and then precipitation regime. It was also found that grouped weather types of weather regimes had more impact on generalized than focal epileptic seizures. Local geomagnetic activity had no direct effect on the occurrence of epileptic seizures. Those results confirm the thesis how the impact of certain external factors is complex and that the further study is required in that respect.

Reflex seizures induced by micturition: a case report

Background

Reflex seizures (RS) induced by micturition are extremely rare, and the clinical and electroencephalogram features of RS are not widely known among clinicians. In particular, the origin of the epileptic area is still unclear.

Case presentation

An 8-year-old girl who had generalized tonic-clonic seizures was diagnosed with RS induced by micturition based on the clinical manifestation and EEG recordings. We also reviewed the clinical and EEG characteristics of RS induced by micturition in literature by searching the databases of PubMed and MEDLINE using keywords “micturition reflex seizure”, “reflex seizure induced by micturition”, and “micturition induced seizure” by January 2022. We speculate that the mechanism of micturition-induced RS may involve excessive neuronal excitation in regions that participate in micturition.

Conclusions

The RS in this patient was considered to be induced by micturition. Awareness should be raised to this rare form of RS among practitioners.

Where words are powerless to express: Use of music in paediatric neurology

Music is an art form that strongly affects people and can elicit many different emotions at the same time, including happiness, anxiety, sadness, and even ecstasy. What is it about music that causes such a strong reaction from each of us? Music engages many senses, which in turn can produce a multiplicity of responses and help create more extensive neuronal connections, as well as influence behaviour through structural and functional changes in the brain. Music-based interventions as a therapeutic tool in rehabilitation are becoming more common. It is said that the impact of music on the human body is positive. However, what impact does music have on the young nervous system, especially the affected one? This review presents the advantages and disadvantages of the use of music in paediatric neurology to treat dyslexia, cerebral palsy, and stroke, among others. Potential negative impacts such as musicogenic epilepsy and hallucinations will be discussed.

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.

Symptomatic eating epilepsy: two novel pediatric patients and review of literature

Eating epilepsy (EE) is a form of reflex epilepsy in which seizures are triggered by eating. It is a rare condition but a high prevalence has been reported in Sri Lanka. In EE, the ictal semiology includes focal seizures with or without secondary generalization or generalized seizures. Some cases are idiopathic while focal structural changes on imaging, if present, are often confined to the temporal lobe or perisylvian region. On the other hand, some cases support the hypothesis of a genetic aetiology. The prognosis of EE is extremely variable due to the different nature of the underlying disorder. We describe two patients with symptomatic eating epilepsy, a 13-year-old boy with a bilateral perisylvian polymicrogyria and a 2-year-old boy with a genetic cause. The presence of structural lesions or the dysfunction of specific cortical regions in the context of a germline genetic alteration might lead to a hyperexcitation fostering the epileptogenesis. We review the available literature to clarify the aetiopathogenesis and the mechanisms underlying EE to improve the diagnosis and the management of these rare conditions.

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.

Seizures triggered by eating - A rare form of reflex epilepsy: A systematic review

Eating epilepsy is a rare disorder, characterised by reflex seizures induced by food intake. It is highly heterogenous, with clinical signs and EEG findings varying between patients. However, common features do emerge from the reported literature. The aim of this systematic review was to bring together this information to facilitate understanding and recognition. We therefore searched electronic databases (PubMed, Scopus, Medline) for relevant studies using keywords 'epilepsy', 'seizure' and 'eating' in March 2020. Human studies, written in English, that reported on cohorts of patients with eating epilepsy were included. Fifty-two unique papers were consequently identified, describing seizure characteristics and diagnostic features in 378 patients. Eating seizures began in the second decade of life, with a higher incidence in males. They were typically focal-onset, and most commonly of the focal impaired awareness type. Pharmacological therapy with one or multiple agents was noted in 80 % of cases, with poor control reported in approximately 25 % of patients. While this retrospective work highlights key features, it is important that future studies implicate video EEG to fully evaluate this highly unique and interesting disorder.

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.

Role of Adenosine in Epilepsy and Seizures

Adenosine is an endogenous anticonvulsant and neuroprotectant of the brain. Seizure activity produces large quantities of adenosine, and it is this seizure-induced adenosine surge that normally stops a seizure. However, within the context of epilepsy, adenosine plays a wide spectrum of different roles. It not only controls seizures (ictogenesis), but also plays a major role in processes that turn a normal brain into an epileptic brain (epileptogenesis). It is involved in the control of abnormal synaptic plasticity and neurodegeneration and plays a major role in the expression of comorbid symptoms and complications of epilepsy, such as sudden unexpected death in epilepsy (SUDEP). Given the important role of adenosine in epilepsy, therapeutic strategies are in development with the goal to utilize adenosine augmentation not only for the suppression of seizures but also for disease modification and epilepsy prevention, as well as strategies to block adenosine A_2A receptor overfunction associated with neurodegeneration. This review provides a comprehensive overview of the role of adenosine in epilepsy.

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.

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.

Seizure-precipitating factors in dogs with idiopathic epilepsy

Background

Stress, sleep deprivation, and infectious diseases are important seizure‐precipitating factors in human epilepsy patients. However, these factors have not been thoroughly studied in epileptic dogs.

Objective

Seizure‐precipitating factors are common in dogs with idiopathic epilepsy and the occurrence of these factors associate with the dogs' signalment, personality, and epilepsy‐related factors.

Animals

Fifty dogs with diagnosed idiopathic epilepsy from the hospital populations of University Veterinary Teaching Hospital of University of Helsinki and Referral Animal Hospital Aisti.

Methods

In a retrospective cross‐sectional observational study, owners were interviewed about their dogs' possible seizure‐precipitating factors according to a predefined questionnaire. The dogs were identified and selected by searching the medical records of the participating animal hospitals.

Results

The prevalence of seizure‐precipitating factors in the study population was 74% (37/50). The most frequently reported factors included stress‐related situations, sleep deprivation, weather, and hormonal factors. In dogs with focal onset seizures, the number of precipitating factors was 1.9 (95% CI 1.1‐3.4) times higher compared to dogs with generalized seizures.

Conclusions and Clinical Importance

Seizure‐precipitating factors are common in dogs with idiopathic epilepsy, and the nature of these factors is consistent with those of human patients. Aside from antiepileptic medication, acknowledging and avoiding seizure‐precipitating factors could help veterinarians achieve better treatment outcomes.

Audiogenic kindling and secondary subcortico-cortical epileptogenesis: Behavioral correlates and electrographic features

Human epilepsy is usually considered to result from cortical pathology, but animal studies show that the cortex may be secondarily involved in epileptogenesis, and cortical seizures may be triggered by extracortical mechanisms. In the audiogenic kindling model, recurrent subcortical (brainstem-driven) seizures induce secondary epileptic activation of the cortex. The present review focuses on behavioral and electrographic features of the subcortico-cortical epileptogenesis: (1) behavioral expressions of traditional and mild paradigms of audiogenic kindling produced by full-blown (generalized) and minimal (focal) audiogenic seizures, respectively; (2) electrographic manifestations of secondary epileptic activation of the cortex - cortical epileptic discharge and cortical spreading depression; and (3) persistent individual asymmetry of minimal audiogenic seizures and secondary cortical events produced by their repetition. The characteristics of audiogenic kindling suggest that this model represents a unique experimental approach to studying cortical epileptogenesis and network aspects of epilepsy. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Weather as a risk factor for epileptic seizures: A case-crossover study

OBJECTIVE

Most epileptic seizures occur unexpectedly and independently of known risk factors. We aimed to evaluate the clinical significance of patients' perception that weather is a risk factor for epileptic seizures.

METHODS

Using a hospital-based, bidirectional case-crossover study, 604 adult patients admitted to a large university hospital in Central Germany for an unprovoked epileptic seizure between 2003 and 2010 were recruited. The effect of atmospheric pressure, relative air humidity, and ambient temperature on the onset of epileptic seizures under temperate climate conditions was estimated.

RESULTS

We found a close-to-linear negative correlation between atmospheric pressure and seizure risk. For every 10.7 hPa lower atmospheric pressure, seizure risk increased in the entire study population by 14% (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.01-1.28). In patients with less severe epilepsy treated with one antiepileptic medication, seizure risk increased by 36% (1.36, 1.09-1.67). A high relative air humidity of >80% increased seizure risk in the entire study population by up to 48% (OR 1.48, 95% CI 1.11-1.96) 3 days after exposure in a J-shaped association. High ambient temperatures of >20°C decreased seizure risk by 46% in the overall study population (OR 0.54, 95% CI 0.32-0.90) and in subgroups, with the greatest effects observed in male patients (OR 0.33, 95% CI 0.14-0.74).

SIGNIFICANCE

Low atmospheric pressure and high relative air humidity are associated with an increased risk for epileptic seizures, whereas high ambient temperatures seem to decrease seizure risk. Weather-dependent seizure risk may be accentuated in patients with less severe epilepsy. Our results require further replication across different climate regions and cohorts before reliable clinical recommendations can be made.

Ecstatic Epileptic Seizures: A Glimpse into the Multiple Roles of the Insula

Ecstatic epileptic seizures are a rare but compelling epileptic entity. During the first seconds of these seizures, ecstatic auras provoke feelings of well-being, intense serenity, bliss, and "enhanced self-awareness." They are associated with the impression of time dilation, and can be described as a mystic experience by some patients. The functional neuroanatomy of ecstatic seizures is still debated. During recent years several patients presenting with ecstatic auras have been reported by others and us (in total n = 52); a few of them in the setting of presurgical evaluation including electrical brain stimulation. According to the recently recognized functions of the insula, and the results of nuclear brain imaging and electrical stimulation, the ecstatic symptoms in these patients seem to localize to a functional network centered around the anterior insular cortex, where we thus propose to locate this rare ictal phenomenon. Here we summarize the role of the multiple sensory, autonomic, affective, and cognitive functions of the insular cortex, which are integrated into the creation of self-awareness, and we suggest how this system may become dysfunctional on several levels during ecstatic aura.

Clinical characteristics and prognosis of mah-jong-induced epilepsy: A cohort review of 56 patients

OBJECTIVE

The objective of this study was to investigate the clinical characteristics of reflex epilepsy elicited by playing mah-jong in Western China.

METHODS

Consecutive patients with reflex epilepsy triggered by mah-jong from Jan 2011 to April 2014 were recruited at West China Hospital. Each patient underwent EEG recording and brain MRI scan. All clinical data were reviewed. Each patient had at least 12 months of follow-up.

RESULTS

Fifty-six patients were included, with majority of them being male (52/56, 92.9%). Mean age was 43.9 ± 10.0 years. Mean age at seizure onset was 35.1 ± 16.3 years. Mean duration of reflex epilepsy was 4.0 ± 2.2 years. The mean follow-up time was 32.0 ± 13.2 months. Seventeen patients (30.4%) took antiepileptic drugs. Regardless of the medication, all 14 patients who avoided playing mah-jong reached seizure freedom, and 22 of the 42 patients (52.4%) who still played mah-jong continued to have seizures (p<0.05).

CONCLUSIONS

Reflex epilepsy induced by mah-jong is a unique type of epilepsy in the Chinese population and usually occurs in adults after a long time lag of playing mah-jong. Avoiding the triggers is the most effective treatment for epilepsy.

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

Epileptic seizures are generally unpredictable and arise spontaneously. Patients often report non-specific triggers such as stress or sleep deprivation, but only rarely do seizures occur as a reflex event, in which they are objectively and consistently modulated, precipitated, or inhibited by external sensory stimuli or specific cognitive processes. The seizures triggered by such stimuli and processes in susceptible individuals can have different latencies. Once seizure-suppressing mechanisms fail and a critical mass (the so-called tipping point) of cortical activation is reached, reflex seizures stereotypically manifest with common motor features independent of the physiological network involved. The complexity of stimuli increases from simple sensory to complex cognitive-emotional with increasing age of onset. The topography of physiological networks involved follows the posterior-to-anterior trajectory of brain development, reflecting age-related changes in brain excitability. Reflex seizures and traits probably represent the extremes of a continuum, and understanding of their underlying mechanisms might help to elucidate the transition of normal physiological function to paroxysmal epileptic activity.