PIEZO1 expression at the glio-vascular unit adjusts to neuroinflammation in seizure conditions.

Mechanosensors are emerging players responding to hemodynamic and physical inputs. Their significance in the central nervous system remains relatively uncharted. Using human-derived brain specimens or cells and a pre-clinical model of mesio-temporal lobe epilepsy (MTLE), we examined how the mRNA levels of the mechanosensitive channel PIEZO1 adjust to disease-associated pro-inflammatory trajectories. In brain tissue micro-punches obtained from 18 drug-resistant MTLE patients, PIEZO1 expression positively correlated with pro-inflammatory biomarkers TNFα, IL-1ß, and NF-kB in the epileptogenic hippocampus compared to the adjacent amygdala and temporal cortex tissues. In an experimental MTLE model, hippocampal Piezo1 and cytokine expression levels were increased post-status epilepticus (SE) and during epileptogenesis. Piezo1 expression positively correlated with Tnfα, Il1ß, and Nf-kb in the hippocampal foci. Next, by combining RNAscope with immunohistochemistry, we identified Piezo1 in glio-vascular cells. Post-SE and during epileptogenesis, ameboid IBA1 microglia, hypertrophic GFAP astrocytes, and damaged NG2DsRed pericytes exhibited time-dependent patterns of increased Piezo1 expression. Digital droplet PCR analysis confirmed the Piezo1 trajectory in isolated hippocampal microvessels in the ipsi and contralateral hippocampi. The combined examinations performed in this model showed Piezo1 expression returning towards basal levels after the epileptogenesis-associated peak inflammation. From these associations, we next asked whether pro-inflammatory players directly regulate PIEZO1 expression. We used human-derived brain cells and confirmed that endothelium, astrocytes, and pericytes expressed PIEZO1. Exposure to human recombinant TNFα or IL1ß upregulated NF-kB in all cells. Furthermore, TNFα induced PIEZO1 expression in a dose and time-dependent manner, primarily in astrocytes. This exploratory study describes a spatiotemporal dialogue between PIEZO1 brain cell-mechanobiology and neuro-inflammatory cell remodeling. The precise functional mechanisms regulating this interplay in disease conditions warrant further investigation.

In vivo γ-aminobutyric acid increase as a biomarker of the epileptogenic zone: An unbiased metabolomics approach.

OBJECTIVE: Following surgery, focal seizures relapse in 20% to 50% of cases due to the difficulty of delimiting the epileptogenic zone (EZ) by current imaging or electrophysiological techniques. Here, we evaluate an unbiased metabolomics approach based on ex vivo and in vivo nuclear magnetic resonance spectroscopy (MRS) methods to discriminate the EZ in a mouse model of mesiotemporal lobe epilepsy (MTLE). METHODS: Four weeks after unilateral injection of kainic acid (KA) into the dorsal hippocampus of mice (KA-MTLE model), we analyzed hippocampal and cortical samples with high-resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS). Using advanced multivariate statistics, we identified the metabolites that best discriminate the injected dorsal hippocampus (EZ) and developed an in vivo MEGAPRESS MRS method to focus on the detection of these metabolites in the same mouse model. RESULTS: Multivariate analysis of HRMAS data provided evidence that γ-aminobutyric acid (GABA) is largely increased in the EZ of KA-MTLE mice and is the metabolite that best discriminates the EZ when compared to sham and, more importantly, when compared to adjacent brain regions. These results were confirmed by capillary electrophoresis analysis and were not reversed by a chronic exposition to an antiepileptic drug (carbamazepine). Then, using in vivo noninvasive GABA-edited MRS, we confirmed that a high GABA increase is specific to the injected hippocampus of KA-MTLE mice. SIGNIFICANCE: Our strategy using ex vivo MRS-based untargeted metabolomics to select the most discriminant metabolite(s), followed by in vivo MRS-based targeted metabolomics, is an unbiased approach to accurately define the EZ in a mouse model of focal epilepsy. Results suggest that GABA is a specific biomarker of the EZ in MTLE.

Epilepsy diagnostic and treatment needs identified with a collaborative database involving tertiary centers in France.

OBJECTIVE: To obtain perspective on epilepsy in patients referred to tertiary centers in France, and describe etiology, epilepsy syndromes, and identify factors of drug resistance and comorbidities. METHODS: We performed a cross-sectional analysis of the characteristics of 5,794 pediatric and adult patients with epilepsy included in a collaborative database in France between 2007 and 2013. Comparisons between groups used Student's t-test or Fisher's exact test for binary or categorical variables. Factors associated with drug resistance and intellectual disability were evaluated in multi-adjusted logistic regression models. RESULTS: Mean age at inclusion was 17.9 years; children accounted for 67%. Epilepsy was unclassified in 20% of patients, and etiology was unknown in 65%, including those with idiopathic epilepsies. Etiologies differed significantly in adult- when compared to pediatric-onset epilepsy; however, among focal structural epilepsies, mesial temporal lobe epilepsy with hippocampal sclerosis began as often in the pediatric as in adult age range. Drug resistance concerned 53% of 4,210 patients evaluable for seizure control and was highest in progressive myoclonic epilepsy (89%), metabolic diseases (84%), focal cortical dysplasia (70%), other cortical malformations (69%), and mesial temporal lobe epilepsy with hippocampal sclerosis (67%). Fifty-nine percent of patients with focal structural epilepsy and 69% with epileptic encephalopathies were drug resistant; however, 40-50% of patients with West syndrome and epileptic encephalopathy with continuous spike-and-waves during sleep were seizure-free. Ages at onset in infancy and in young adults shared the highest risk of drug resistance. Epilepsy onset in infancy comprised the highest risk of intellectual disability, whereas specific cognitive impairment affected 36% of children with idiopathic focal epilepsy. SIGNIFICANCE: Our study provides a snapshot on epilepsy in patients referred to tertiary centers and discloses needs for diagnosis and treatment. Large databases help identify patients with rare conditions that could benefit from specific prospective studies.

Long-term modifications of epileptogenesis and hippocampal rhythms after prolonged hyperthermic seizures in the mouse.

Complex febrile seizures are often reported in the history of patients with mesio-temporal lobe epilepsy (MTLE) but their role in its physiopathology remains controversial. We postulated that prolonged hyperthermic seizures might, as a "single-hit", modify the hippocampal rhythms, facilitate epileptogenesis and influence subsequent epilepsy when a second-hit already exists or subsequently occurs. To test this hypothesis, we examined the effects of hyperthermic seizures (30min at 40-41°C) at postnatal day 10 on hippocampal activity in C57BL/6J mice in comparison to their littermates in sham conditions (22°C), with or without another insult. Using local field potential, we observed an asymmetry in the hippocampal susceptibility to seize in hyperthermic conditions. When these mice were adult, an asymmetrical increase of low frequency power was also recorded in the hippocampus when compared to sham animals. Using two different "two-hit" protocols, no increase in seizures or hippocampal discharge frequency or duration was observed, either in mice with a genetic CA3 dysplasia (Dcx knockout), or in mice injected with kainate into the dorsal hippocampus at P60. However, in the latter condition, which is reminiscent of MTLE, the hyperthermic seizures accelerated epileptogenesis and decreased the power in the high frequency gamma band, as well as decreasing the coherence between hippocampi and the involvement of the contralateral hippocampus during hippocampal paroxysmal discharges. Our data suggest that a single episode of prolonged hyperthermic seizures does not induce per se, but accelerates epileptogenesis and could lead to an asymmetrical dysfunction in the hippocampal rhythmicity in both physiological and pathological conditions.

A simple febrile seizure with focal onset.

Simple febrile seizures last for less than 10 minutes and resolve spontaneously, in the context of a febrile illness, without focal features or recurrence during the subsequent 24 hours. We report the case of fortuitous video-EEG recording of a FS, clinically classified as "simple", which demonstrated a focal, temporal onset. This clinical finding is in agreement with animal model studies demonstrating focal onset.

Low-frequency photoparoxysmal response in adults: an early clue to diagnosis.

Intermittent photic stimulation is performed during an EEG to evoke photoparoxysmal response. When they appear triggered by low-frequency stimulation in children, they are suggestive of rare diagnosis, that is, neuronal ceroid lipofuscinosis. Among adults, their significance is less well understood. Low-frequency (<5 Hz) intermittent photic stimulation was performed over a period of 5 years during adult standard EEG. This retrospective study included all patients exhibiting low-frequency photoparoxysmal response. Five cases were identified. Three of them presented with active epilepsy (two progressive myoclonus epilepsy, one unclassifiable), two had visual deficiency, and three had dementia. The etiologies were MELAS (two), Creutzfeldt-Jakob disease (one), Kufs disease (one), and remained undetermined for one patient. In all patients, low-frequency photoparoxysmal response was observed years or months before the final diagnoses have been reached. Low-frequency photoparoxysmal response, classically associated with childhood progressive myoclonus epilepsy, seems to have a wider etiological spectrum in adult population. Moreover, this neurophysiological feature could be present before the final diagnosis in most cases. Systematically testing low frequencies during intermittent photic stimulation even during adult EEG seems warranted, particularly in a context of severe progressive neurologic deterioration.

Dentate gyrus and hilus transection blocks seizure propagation and granule cell dispersion in a mouse model for mesial temporal lobe epilepsy.

Epilepsy-associated changes of the anatomical organization of the dentate gyrus and hilus may play a critical role in the initiation and propagation of seizures in mesial temporal lobe epilepsy (MTLE). This study evaluated the role of longitudinal projections in the propagation of hippocampal paroxysmal discharges (HPD) in dorsal hippocampus by performing a selective transection in a mouse model for MTLE obtained by a single unilateral intrahippocampal injection of kainic acid (KA). Full transections of the dentate gyrus and hilus were performed in the transverse axis at 22 days after KA injection when spontaneous HPD were fully developed. They: (i) significantly reduced the occurrence of HPD; (ii) increased their duration at the KA injection site; (iii) abolished their spread along the longitudinal axis of the hippocampal formation and; (iv) limited granule cell dispersion (GCD) of the dentate gyrus posterior to the transection. These data suggest that: (i) longitudinal projections through the dentate gyrus and hilus are involved in HPD spread; (ii) distant hippocampal circuits participate in the generation and cessation of HPD and; (iii) GCD requires continuous HPD to develop, even when seizures are established. Our data reveal a critical role for longitudinal projections in the generation and spread of hippocampal seizures.

Fatigue in epilepsy: a prospective inter-ictal and post-ictal survey.

PURPOSE: Fatigue represents a frequent complaint in epileptic patients (EP). This study attempted to evaluate fatigue in both conditions (inter-ictally and post-ictally) and to investigate the relative contribution of depression, sleepiness and epilepsy characteristics. METHODS: Consecutive EP were enrolled prospectively during a 3-month period, providing they were aged over 15 and able to fill auto-questionnaires. Age, gender, co-morbidities, seizure frequency, treatment, epilepsy syndrome, seizure lateralization and localization and last seizure occurrence were collected. Fatigue, depression and sleepiness were evaluated in both groups using the Fatigue Impact Scale (FIS), the Beck Depression Inventory (BDI), and the Epworth Sleepiness Scale (ESS). Furthermore, FIS was prospectively scored by patients post-ictally (within 24h after an incident seizure). RESULTS: 122 EP filled inclusion criteria (65 women, mean age 39±15). Among them, 82% presented with non-idiopathic partial epilepsy and 18% idiopathic generalized epilepsy. EP exhibit high chronic fatigue scores (62/160) irrespective of the type of epilepsy, seizure frequency, and number of antiepileptic drugs. FIS score was higher in post-ictally (79/160) than inter-ictally. FIS positively correlated with BDI and ESS. DISCUSSION: Chronic inter-ictal and post-ictal fatigue could represent a further complication of epilepsy, associated with depression. The impact of fatigue should be considered with the aim of improving quality of life and care of patients with epilepsy.

De novo epileptic confusion in the elderly: a 1-year prospective study.

PURPOSE: Nonconvulsive status epilepticus (NCSE) is clinically difficult to diagnose, especially in old patients without epilepsy, and requires electroencephalography (EEG) for diagnosis. Its incidence among elderly patients with confusion of unknown origin (CUO) remains undetermined. METHODS: A 1-year prospective study was conducted in patients aged 60 years or older, for whom EEG was requested because of confusion considered to be of unknown origin after initial clinical, biologic, and imaging investigations. Diagnosis criteria included a validated clinical assessment scale to confirm confusion. RESULTS: Of 44 patients with confirmed CUO, 7 presented with de novo NCSE. NCSE population had a mean age of 76 years (range, 60-97 years). No statistically significant differences were found between NCSE patients and others for age, drugs, presence of myoclonia, eyelid myoclonia, tachycardia, or agitation. In contrast, an acute onset (<24 h), gender (100% female among NCSE patients), and lack of clinical response to simple commands were significantly associated with NCSE. No differences between the two groups were evidenced for mortality and morbidity (length of hospitalization, social outcome, and so on). DISCUSSION: Almost 16% of patients aged 60 or older with confusion of unknown origin had NCSE, according to this first prospective study. Female patients with rapid onset (<24 h) of symptoms and lack of response to simple commands were at a higher risk of presenting with NCSE.

Late onset hyperekplexia.

We report on the case of an 86-year-old woman who rapidly became unable to stand and walk because of jerky movements, suggesting a clinical diagnosis of myoclonus. It was observed that both unexpected and expected stimuli (audiogenic, tactile, or visual) triggered the myoclonic jerks. Electrophysiological exploration, including a coupled EEG-EMG study, showed the occurrence of a patterned motor response to each stimulation (whatever the modality), consisting of eye blinking, head flexion, abduction of the upper arms, movement of the trunk, and bending of the knees. Given the absence of any relevant past history and lack of biological or neurological abnormalities including on CT scan brain imaging, the diagnosis of late-onset hyperekplexia was suggested. Substantial abatement of the clinical symptomatology was obtained after introduction of low-dose clonazepam.