Familial mesial temporal lobe epilepsy and the borderland of déjà vu

Familial mesial temporal lobe epilepsy phenotype is associated with novel LGI1 variants: A report of two families

OBJECTIVE

To expand the clinical phenotype and mutation spectrum of familial mesial temporal lobe epilepsy (FMTLE) and provide a new perspective for exploring the pathological mechanisms of epilepsy caused by leucine-rich glioma inactivated 1 (LGI1) variants.

METHODS

We reported clinical data from two families with FMTLE and screened patients for variants in the LGI1 gene using Whole-exome sequencing and Sanger sequencing. The clinical features of FMTLE were analysed. The pathogenicity of the causative loci was assessed according to the American College of Medical Genetics and Genomics guidelines, and potential pathogenic mechanisms were predicted through multiple bioinformatics and molecular dynamics software.

RESULTS

We identified two novel LGI1 truncating variants within two large families with FMTLE: LGI1 (c.1174C>T, p.Q392X) and LGI1 (c.703C>T, p.Q235X). Compared to previous reports, we found that focal to bilateral tonic-clonic seizures are a common type of seizure in FMTLE. The clinical phenotypes of patients with FMTLE caused by LGI1 variants were relatively mild, and all patients responded well to valproic acid. Bioinformatics analyses and molecular dynamics simulations showed that protein structure and interactions were considerably weakened or damaged as a result of both variants.

CONCLUSION

This study presents the first report identifying LGI1 as a potential novel pathogenic gene within FMTLE families, thereby broadening the mutation spectrum associated with FMTLE. The findings of this study offer novel insights and avenues for understanding the intricate molecular mechanisms underlying LGI1 variants and their correlations with patient phenotypes. This study proposes the possibility of familial focal epilepsy syndromes overlapping.

Non-ictal, interictal and ictal déjà vu: a systematic review and meta-analysis

Background

Déjà vu, French for "already seen," is a phenomenon most people will experience at least once in their lifetime. Emerging evidence suggests that déjà vu occurs in healthy individuals (as "non-ictal déjà vu") and in epilepsy patients during seizures (as "ictal déjà vu") and between seizures (as "interictal déjà vu"). Although the ILAE has recognized déjà vu as a feature of epileptic seizures, it is notably absent from the ICD-11. A lack of evidence-based research may account for this omission. To our knowledge, this study represents the first systematic review and meta-analysis on déjà vu experiences. Through detailed examinations of non-ictal, interictal and ictal déjà vu, we seek to highlight possible clinical implications. Rethinking the status quo of ictal déjà vu could potentially lead to earlier interventions and improve outcomes for epilepsy patients.

Methods

This study was registered in PROSPERO (ID: CRD42023394239) on 5 February 2023. Systematic searches were conducted across four databases: EMBASE, MEDLINE, PsycINFO, and PubMed, from inception to 1 February 2023, limited to English language and human participants. Studies were included/excluded based on predefined criteria. Data was extracted according to the PICO framework and synthesized through a thematic approach. Meta-analyses were performed to estimate prevalence's of the phenomena. Study quality, heterogeneity, and publication bias were assessed.

Results

Database searching identified 1,677 records, of which 46 studies were included. Meta-analyses of prevalence showed that non-ictal déjà vu was experienced by 0.74 (95% CI [0.67, 0.79], p < 0.001) of healthy individuals, whereas interictal déjà vu was experienced by 0.62 (95% CI [0.48, 0.75], p = 0.099) and ictal déjà vu by 0.22 (95% CI [0.15, 0.32], p = 0.001) of epilepsy patients. Examinations of phenomenological (sex, age, frequency, duration, emotional valence, and dissociative symptoms) and neuroscientific (brain structures and functions) data revealed significant variations between non-ictal, interictal and ictal déjà vu on several domains.

Conclusion

This systematic review and meta-analysis do not support the notion that non-ictal, interictal and ictal déjà vu are homogenous experiences. Instead, it provides insight into ictal déjà vu as a symptom of epilepsy that should be considered included in future revisions of the ICD-11.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=394239, CRD42023394239.

Towards a conflict account of déjà vu: The role of memory errors and memory expectation conflict in the experience of déjà vu

Déjà vu can be defined as conflict between a subjective evaluation of familiarity and a concurrent evaluation of novelty. Accounts of the déjà vu experience have not explicitly referred to a "conflict account of déjà vu" despite the acceptance of conflict-based definitions of déjà vu and relatively recent neuroimaging work that has implicated brain areas associated with conflict as underpinning the experience. Conflict monitoring functioning follows a similar age-related trajectory to déjà vu with a peak in young adulthood and a subsequent age-related decline. In this narrative review of the literature to date, we consider how déjà vu is defined and how this has influenced the understanding of déjà vu. We also review how déjà vu can be understood within theories of recognition memory and cognitive control. Finally, we summarise the conflict account of déjà vu and propose that this account of the experience may provide a coherent explanation as to why déjà vu experiences tend to decrease with age in the non-clinical population.

Familial Mesial Temporal Lobe Epilepsy: Clinical Spectrum and Genetic Evidence for a Polygenic Architecture

OBJECTIVE

Familial mesial temporal lobe epilepsy (FMTLE) is an important focal epilepsy syndrome; its molecular genetic basis is unknown. Clinical descriptions of FMTLE vary between a mild syndrome with prominent déjà vu to a more severe phenotype with febrile seizures and hippocampal sclerosis. We aimed to refine the phenotype of FMTLE by analyzing a large cohort of patients and asked whether common risk variants for focal epilepsy and/or febrile seizures, measured by polygenic risk scores (PRS), are enriched in individuals with FMTLE.

METHODS

We studied 134 families with ≥ 2 first or second-degree relatives with temporal lobe epilepsy, with clear mesial ictal semiology required in at least one individual. PRS were calculated for 227 FMTLE cases, 124 unaffected relatives, and 16,077 population controls.

RESULTS

The age of patients with FMTLE onset ranged from 2.5 to 70 years (median = 18, interquartile range = 13-28 years). The most common focal seizure symptom was déjà vu (62% of cases), followed by epigastric rising sensation (34%), and fear or anxiety (22%). The clinical spectrum included rare cases with drug-resistance and/or hippocampal sclerosis. FMTLE cases had a higher mean focal epilepsy PRS than population controls (odds ratio = 1.24, 95% confidence interval = 1.06, 1.46, p = 0.007); in contrast, no enrichment for the febrile seizure PRS was observed.

INTERPRETATION

FMTLE is a generally mild drug-responsive syndrome with déjà vu being the commonest symptom. In contrast to dominant monogenic focal epilepsy syndromes, our molecular data support a polygenic basis for FMTLE. Furthermore, the PRS data suggest that sub-genome-wide significant focal epilepsy genome-wide association study single nucleotide polymorphisms are important risk variants for FMTLE. ANN NEUROL 2023;94:825-835.

Association of Deja Vu with Cardiovascular Diseases

Recent studies have suggested a link between déjà vu and cardiovascular diseases. While the mechanism for this association is not fully understood, one theory suggests that déjà vu may be a result of a disruption in the temporal lobe, which is also responsible for regulating blood pressure and heart rate. Another theory suggests that there may be a shared genetic factor between the two conditions, with certain individuals being predisposed to experiencing both. The APOE (Apolipoprotein E) gene, in particular, has been associated with memory processing, Alzheimer's disease, and an increased risk of cardiovascular disease. The protein encoded by this gene is involved in the metabolism of lipoproteins, including cholesterol and triglycerides, and is also involved in the development of atherosclerosis, which is a key risk factor for cardiovascular disease. Several hypotheses have been proposed to explain how the APOE4 isoform contributes to CVD, including impairing the clearance of lipoproteins, promoting inflammation, and causing endothelial dysfunction. Psychological factors such as stress may also contribute to the development of cardiovascular disease, and déjà vu may be associated with emotional arousal and stress. Further research is needed to fully understand the link between déjà vu and cardiovascular diseases and to explore potential treatment options for individuals who experience both conditions.

Gene expression profile suggests different mechanisms underlying sporadic and familial mesial temporal lobe epilepsy

Most patients with pharmacoresistant mesial temporal lobe epilepsy (MTLE) have hippocampal sclerosis on the postoperative histopathological examination. Although most patients with MTLE do not refer to a family history of the disease, familial forms of MTLE have been reported. We studied surgical specimens from patients with MTLE who had epilepsy surgery for medically intractable seizures. We assessed and compared gene expression profiles of the tissue lesion found in patients with familial MTLE (n = 3) and sporadic MTLE (n = 5). In addition, we used data from control hippocampi obtained from a public database (n = 7). We obtained expression profiles using the Human Genome U133 Plus 2.0 (Affymetrix) microarray platform. Overall, the molecular profile identified in familial MTLE differed from that in sporadic MTLE. In the tissue of patients with familial MTLE, we found an over-representation of the biological pathways related to protein response, mRNA processing, and synaptic plasticity and function. In sporadic MTLE, the gene expression profile suggests that the inflammatory response is highly activated. In addition, we found enrichment of gene sets involved in inflammatory cytokines and mediators and chemokine receptor pathways in both groups. However, in sporadic MTLE, we also found enrichment of epidermal growth factor signaling, prostaglandin synthesis and regulation, and microglia pathogen phagocytosis pathways. Furthermore, based on the gene expression signatures, we identified different potential compounds to treat patients with familial and sporadic MTLE. To our knowledge, this is the first study assessing the mRNA profile in surgical tissue obtained from patients with familial MTLE and comparing it with sporadic MTLE. Our results clearly show that, despite phenotypic similarities, both forms of MTLE present distinct molecular signatures, thus suggesting different underlying molecular mechanisms that may require distinct therapeutic approaches.

Treatment gaps in epilepsy

Over 50 million people around the world have epilepsy, and yet, epilepsy recognition and access to care are ongoing issues. Nearly 80% of people with epilepsy live in low-and middle-income countries and face the greatest barriers to quality care. However, there are substantial disparities in care within different communities in high-income countries as well. Across the world, under-recognition of seizures continues to be an issue, leading to diagnostic and treatment delays. This stems from issues surrounding stigma, public education, basic access to care, as well as healthcare worker education. In different regions, people may face language barriers, economic barriers, and technological barriers to timely diagnosis and treatment. Even once diagnosed, people with epilepsy often face gaps in optimal seizure control with the use of antiseizure medications. Additionally, nearly one-third of people with epilepsy may be candidates for epilepsy surgery, and many either do not have access to surgical centers or are not referred for surgical evaluation. Even those who do often experience delays in care. The purpose of this review is to highlight barriers to care for people with epilepsy, including issues surrounding seizure recognition, diagnosis of epilepsy, and the initiation and optimization of treatment.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset at a variable age: position statement by the ILAE Task Force on Nosology and Definitions

The goal of this paper is to provide updated diagnostic criteria for the epilepsy syndromes that have a variable age of onset, based on expert consensus of the International League Against Epilepsy Nosology and Definitions Taskforce (2017-2021). We use language consistent with current accepted epilepsy and seizure classifications and incorporate knowledge from advances in genetics, electroencephalography, and imaging. Our aim in delineating the epilepsy syndromes that present at a variable age is to aid diagnosis and to guide investigations for etiology and treatments for these patients.

Subjective distinguishability of seizure and non-seizure Déjà Vu: A case report, brief literature review, and research prospects

Roughly two-thirds of all people report having experienced déjà vu-the odd feeling that a current experience is both novel and a repeat or replay of a previous, unrecalled experience. Reports of an association between déjà vu and seizure aura symptomatology have accumulated for over a century, and frequent déjà vu is also now known to be associated with focal seizures, particularly those of a medial temporal lobe (MTL) origin. A longstanding question is whether seizure-related déjà vu has the same basis and is the same subjective experience as non-seizure déjà vu. Survey research suggests that people who experience both seizure-related and non-seizure déjà vu can often subjectively distinguish between the two. We present a case of a person with a history of focal MTL seizures who reports having experienced both seizure-related and non-seizure common déjà vu, though the non-seizure type was more frequent during this person's youth than it is currently. The patient was studied with a virtual tour paradigm that has previously been shown to elicit déjà vu among non-clinical, young adult participants. The patient reported experiencing déjà vu of the common non-seizure type during the virtual tour paradigm, without associated abnormalities of the intracranial EEG. We situate this work in the context of broader ongoing projects examining the subjective correlates of seizures. The importance for memory research of virtual scenes, spatial tasks, virtual reality (VR), and this paradigm for isolating familiarity in the context of recall failure are discussed.

Female preponderance in genetic generalized epilepsies

INTRODUCTION

Epilepsy is more prevalent in men but Genetic Generalized Epilepsies (GGE) seem to be more common in women. A predominant maternal inheritance has been previously described in GGE. Our objective was to determine sex and inheritance patterns in a GGE population compared to mesial temporal lobe epilepsy with hippocampal sclerosis (MTLEHS).

METHODS

We performed a prospective observational study including adult GGE and MTLEHS patients followed up at a tertiary epilepsy center from January 2016 to December 2019. Patients' familial history was obtained by a detailed questionnaire. Clinical and demographic data was retrieved from clinical notes.

RESULTS

A cohort of 641 patients, 403 with GGE and 238 with MTLEHS, was analyzed. GGE was more common in women than MTLEHS (58.8% vs 44.5%, OR=1.63, p = 0.004). Compared to MTLEHS patients, more GGE patients had familial history of epilepsy (45.4% vs 25.2%; p<0.001). The GGE group had a higher percentage of female relatives with epilepsy (55% vs 37%; p = 0.006). The prevalence of maternal inheritance was not different between GGE and MTLEHS groups (62.9% vs 57.7%; p = 0.596). Photosensitivity was more common in females than in males (44.7% vs 34.3%, p = 0.036).

CONCLUSION

There is a female preponderance in GGE when compared to MTLEHS, as both GGE patients and their affected relatives are more frequently women. The prevalence of maternal inheritance was not higher in GGE than in MTLEHS.

A PIK3R2 Mutation in Familial Temporal Lobe Epilepsy as a Possible Pathogenic Variant

Temporal lobe epilepsy (TLE), the most common form of medically refractory focal epilepsy in adults, often requires surgery to alleviate seizures. By using next-generation sequencing, we identified a PIK3R2 mutation (NM_005027.4: c.265C > T; NP_005018.2: p.Arg89Cys) in a family with mesial temporal lobe epilepsy. PIK3R2 encodes p85β, the regulatory subunit of Class IA phosphoinositide 3-kinase (PI3K) and the mutation we identified in PIK3R2 seems to function unexpectedly as a possible pathogenic variant. The mutation is predicted to be potentially pathogenic by multiple bioinformatics tools. Through a functional assay, we verified that the mutation enhances the function of PI3K in induced pluripotent stem cells (iPSCs) derived from peripheral blood mononuclear cells (PBMCs) of the proband. Finally, pathological testing of the resected temporal lobe cortex showed that the expression of PIK3R2 was significantly higher in patients with refractory temporal lobe epilepsy than in those of non-epileptic diseases as a control group. It can be inferred that PIK3R2 might play an important role in the development of TLE.

The Genetics of Epilepsy

Epilepsy encompasses a group of heterogeneous brain diseases that affect more than 50 million people worldwide. Epilepsy may have discernible structural, infectious, metabolic, and immune etiologies; however, in most people with epilepsy, no obvious cause is identifiable. Based initially on family studies and later on advances in gene sequencing technologies and computational approaches, as well as the establishment of large collaborative initiatives, we now know that genetics plays a much greater role in epilepsy than was previously appreciated. Here, we review the progress in the field of epilepsy genetics and highlight molecular discoveries in the most important epilepsy groups, including those that have been long considered to have a nongenetic cause. We discuss where the field of epilepsy genetics is moving as it enters a new era in which the genetic architecture of common epilepsies is starting to be unraveled.

Epilepsy in adults

Epilepsy is one of the most common serious brain conditions, affecting over 70 million people worldwide. Its incidence has a bimodal distribution with the highest risk in infants and older age groups. Progress in genomic technology is exposing the complex genetic architecture of the common types of epilepsy, and is driving a paradigm shift. Epilepsy is a symptom complex with multiple risk factors and a strong genetic predisposition rather than a condition with a single expression and cause. These advances have resulted in the new classification of epileptic seizures and epilepsies. A detailed clinical history and a reliable eyewitness account of a seizure are the cornerstones of the diagnosis. Ancillary investigations can help to determine cause and prognosis. Advances in brain imaging are helping to identify the structural and functional causes and consequences of the epilepsies. Comorbidities are increasingly recognised as important aetiological and prognostic markers. Antiseizure medication might suppress seizures in up to two-thirds of all individuals but do not alter long-term prognosis. Epilepsy surgery is the most effective way to achieve long-term seizure freedom in selected individuals with drug-resistant focal epilepsy, but it is probably not used enough. With improved understanding of the gradual development of epilepsy, epigenetic determinants, and pharmacogenomics comes the hope for better, disease-modifying, or even curative, pharmacological and non-pharmacological treatment strategies. Other developments are clinical implementation of seizure detection devices and new neuromodulation techniques, including responsive neural stimulation.

Déjà vu experiences in anxiety

Déjà vu occurs when a novel event is experienced with an erroneous sense of familiarity. Memory researchers theorise that this arises due to an error in the processes underlying the recognition memory system. Research has indicated that there may be a link between high levels of anxiety and increased frequency and intensity of déjà vu, however, there has been a comparatively little characterisation of déjà vu as experienced by individuals with clinical anxiety. We used an online questionnaire to collect data from individuals self-reporting a clinical diagnosis of anxiety, as well as from age-matched controls. The Anxiety Group reported a significantly higher frequency of déjà vu episodes over the previous month than controls. They also reported experiencing déjà vu more frequently and with higher intensity during periods of high anxiety. In addition, the Anxiety Group reported finding déjà vu episodes significantly more distressing than the Control Group. The findings indicate that there are differences in déjà vu experienced by people reporting high levels of anxiety compared to healthy controls without an anxiety diagnosis. We discuss structural and neural mechanisms thought to underpin déjà vu in relation to these results.

Genetics of Focal Epilepsies: What Do We Know and Where Are We Heading?

This article is based on a lecture delivered at the 2017 American Epilepsy Society Annual Meeting and provides an overview of the growing evidence supporting the strong genetic contribution to focal epilepsies. This also discusses how advances in the molecular genetics of focal epilepsies are rapidly translating to routine clinical care.

Insight into epileptic and physiological déjà vu: from a multicentric cohort study

BACKGROUND AND PURPOSE

The presence of a continuum between physiological déjà vu (DV) and epileptic DV is still not known as well as epidemiological data in the Italian population. The aim was to identify the epidemiological distribution of DV in Italy, and secondly to look for specific features of DV able to discriminate between epileptic and non-epileptic DV.

METHODS

In all, 1000 individuals, 543 healthy controls (C) (313 women; age 40 ± 15 years) and 457 patients with epilepsy (E) (260 women; age 39 ± 14 years), were prospectively recruited from 10 outpatient neurological clinics throughout Italy. All populations were screened using the Italian Inventory for Déjà Vu Experiences Assessment (I-IDEA) test and E and pairwise C underwent a comprehensive epilepsy interview.

RESULTS

Of E, 69% stated that they experienced 'recognition' and 13.2% reported that this feeling occurred from a few times a month to at least weekly (versus 7.7% of the control group). Furthermore, a greater percentage of E (6.8% vs. 2.2%) reported that from a few times a month to at least weekly they felt that it seemed as though everything around was not real. In E, the feeling of recognition raised fright (22.3% vs. 13.2%) and a sense of oppression (19.4% vs. 9.4%). A fifth of E felt recognition during epileptic seizures.

CONCLUSION

Only E regardless of aetiology firmly answered that they had the feeling of recognition during an epileptic seizure; thus question 14 of the I-IDEA test part 2 discriminated E from C. Paranormal activity, remembering dreams and travel frequency were mostly correlated to DV in E suggesting that the visual-memory network might be involved in epileptic DV.

Phenotypic spectrum in families with mesial temporal lobe epilepsy probands

PURPOSE

The traditional perception of mesial temporal lobe epilepsy (MTLE) as a predominantly acquired disorder is challenged due to emerging evidence of familial aggregation. In this study, we ascertained the extent of familial occurrence of epilepsy in MTLE patients, as well as phenotypic heterogeneity in affected relatives.

METHODS

We identified and reevaluated patients with MTLE, treated at Epilepsy Department for a period of two years. All eligible putatively affected relatives were asked to participate in the study. In addition to comprehensive epilepsy interview, they underwent EEG and MRI studies.

RESULTS

52 patients with MTLE were included; nine of them (17%) had at least one family member with epilepsy. Subsequently, we analyzed nine probands with MTLE and a total of 15 relatives with seizures. Among affected relatives, spectrums of clinical manifestations were observed. Typical MTL seizures were described in five individuals, while other types of focal or generalized tonic-clonic seizures were reported in other ten relatives. A total of seven individuals had febrile seizures. Hippocampal sclerosis was found in three probands and none of the relatives. Two of affected family members had a traumatic brain injury in addition to febrile seizures, prior to the occurrence of their epilepsy.

CONCLUSION

We demonstrate that familiar occurrence of epilepsy and subsequently putative genetic background, accounts for a substantial proportion MTLE patients. In addition, we foreground the remarkable intra- and interfamilial phenotypic heterogeneity than usually described, displaying the complexity of the genotype-phenotype correlations.

Familial temporal lobe epilepsy in the 19th century

PURPOSE

To draw attention to a publication showing that familial temporal lobe epilepsy had been described in 1895, considerably earlier than 1994, usually thought to be the date of the original account of the disorder METHODS: Examination of the contents of Sir James Crichton-Browne's Cavendish lecture on 'Dreamy mental states' that was published in the Lancet in mid-1895 RESULTS: At a time when the clinical phenomena that later became associated with the idea of temporal lobe epilepsy were beginning to become known, Creighton-Browne described the presence of this disorder in members of four consecutive generations of a British family throughout the course of the 19th Century CONCLUSIONS: There is evidence that the genetic abnormality responsible for familial temporal epilepsy had probably appeared considerably earlier than hitherto thought.