Neuroinflammation in Pathogenesis of Audiogenic Epilepsy: Altered Proinflammatory Cytokine Levels in the Rats of Krushinsky-Molodkina Seizure-Prone Strain.

Neuroinflammation plays an important role in epileptogenesis, however, most studies are performed using pharmacological models of epilepsy, while there are only few data available for non-invasive, including genetic, models. The levels of a number of pro-inflammatory cytokines were examined in the Krushinsky-Molodkina (KM) rat strain with high audiogenic epilepsy (AE) proneness (intense tonic seizure fit in response to loud sound) and in the control strain "0" (not predisposed to AE) using multiplex immunofluorescence magnetic assay (MILLIPLEX map Kit). Cytokine levels were determined in the dorsal striatum tissue and in the brain stem. Background levels of IL-1ß, IL-6, and TNF-α in the dorsal striatum of the KM rats were significantly lower than in the rats "0" (by 32.31, 27.84, and 38.87%, respectively, p < 0.05, 0.05, and 0.01), whereas no inter-strain differences in the levels of these metabolites were detected in the brain stem in the "background" state. Four hours after sound exposure, the TNF-α level in the dorsal striatum of the KM rats was significantly lower (by 38.34%, p < 0.01) than in the "0" rats. In the KM rats, the dorsal striatal levels of IL-1ß and IL-6 were significantly higher after the sound exposure and subsequent seizure fit, compared to the background (35.29 and 50.21% increase, p < 0.05, 0.01, respectively). In the background state the IL-2 level in the KM rats was not detected, whereas after audiogenic seizures its level was 14.01 pg/ml (significant difference, p < 0.01). In the KM rats the brain stem levels of IL-1ß and TNF-α after audiogenic seizures were significantly lower than in the background (13.23 and 23.44% decrease, respectively, p < 0.05). In the rats of the "0" strain, the levels of cytokines in the dorsal striatum after the action of sound (which did not induce AE seizures) were not different from those of the background, while in the brain stem of the "0" strain the levels of IL-1ß were lower than in the background (40.28%, p < 0.01). Thus, the differences between the background levels of cytokines and those after the action of sound were different in the rats with different proneness to AE. These data suggest involvement of the analyzed cytokines in pathophysiology of the seizure state, namely in AE seizures.

Focal cortical dysplasia links to sleep-related epilepsy in symptomatic focal epilepsy.

OBJECTIVE: In sleep-related epilepsy (SRE), epileptic seizures predominantly occur during sleep, but the clinical characteristics of SRE remain elusive. We aimed to identify the clinical features associated with the occurrence of SRE in a large cohort of symptomatic focal epilepsy. METHODS: We retrospectively included patients with four etiologies, including focal cortical dysplasia (FCD), low-grade tumors (LGT), temporal lobe epilepsy with hippocampal sclerosis (TLE-HS), and encephalomalacia. SRE was defined as more than 70% of seizures occurring during sleep according to the seizure diary. The correlation between SRE and other clinical variables, such as etiology of epilepsy, pharmacoresistance, seizure frequency, history of bilateral tonic-clonic seizures, and seizure localization was analyzed. RESULTS: A total of 376 patients were included. Among them 95 (25.3%) were classified as SRE and the other 281(74.7%) as non-SRE. The incidence of SRE was 53.5% in the FCD group, which was significantly higher than the other three groups (LGT: 19.0%; TLE-HS: 9.9%; encephalomalacia: 16.7%; P < 0.001). The etiology of FCD (p < 0.001) was significantly associated with SRE (OR: 9.71, 95% CI: 3.35-28.14) as an independent risk factor. In addition, small lesion size (p = 0.009) of FCD further increased the risk of SRE (OR: 3.18, 95% CI: 1.33-7.62) in the FCD group. SIGNIFICANCE: Our data highlight that FCD markedly increased the risk of sleep-related epilepsy independently of seizure localization. A small lesion of FCD further increased the risk of sleep-related epilepsy by 2.18 times in the FCD group.

Predictors of hyperkinetic seizures.

OBJECTIVE: To identify predisposing factors for hyperkinetic seizure occurrence in a representative cohort of surgically treated patients with drug-resistant focal epilepsy. METHODS: We retrospectively recruited all seizure-free patients after epilepsy surgery with a postoperative follow-up ≥12 months. Patients were classified as presenting with hyperkinetic seizures if at least 2 episodes occurred during their disease history, based on clear-cut anamnestic description and/or video-EEG/stereo-EEG recordings. We performed univariable and multivariable logistic regression models to study the association between the occurrence of hyperkinetic seizures and some predictors. RESULTS: From a pool of 1758 consecutive patients who underwent surgery from 1996 to 2017, we identified 974 seizure-free cases. Considering at least 1-year follow-up, 937 cases were included (511 males, 91 patients with hyperkinetic seizures). Variables significantly associated with an increased risk of hyperkinetic seizure occurrence were (1) presence of epilepsy with sleep-related seizures (SRE) (P < 0.001); (2) histological diagnosis of type II focal cortical dysplasia (FCD) (P < 0.001); (3) resection including the frontal lobe (P = 0.002) (4) duration of epilepsy at surgery (P < 0.001) and (5) high seizure frequency at surgery (weekly: P = 0.02 - daily: P = 0.05). A resection including the occipital lobe reduced the risk of hyperkinetic seizures (P = 0.05). About 63% of patients had hyperkinetic seizure onset before 12 years and it was rarely reported before 5 years of age. SIGNIFICANCE: Our findings underlie the role of SRE, type II FCD and frontal epileptogenic zone as predictors of hyperkinetic seizure occurrence and highlight an age-dependent effect in favoring hyperkinetic manifestations.

Clinical and electrophysiological findings in patients with phenylketonuria and epilepsy: Reflex features.

OBJECTIVE: Phenylketonuria (PKU) is the most common form of amino acid metabolism disorders with autosomal recessive inheritance. The brain damage can be prevented by early diagnosis and a phenylalanine-restricted diet. Untreated or late-treated patients may show mental retardation and other cognitive dysfunctions, as well as motor disability and/or epilepsy. METHODS: Three patients with PKU and epilepsy were recognized to have reflex epileptic features, and there were ten consecutive adult patients with PKU and epilepsy who were evaluated retrospectively. Medical history, ages at diagnosis and therapy onset, age at seizure onset, seizure types and reflex features, neurological findings, cranial imaging, electroencephalography (EEG) findings, and final clinical condition were evaluated. Reflex epilepsy features were examined in detail. RESULTS: The cases (6 females, 4 males) were diagnosed at ages between 3.5months and 12years. All patients had various degrees of mental-motor retardation and focal or generalized seizures with age at seizure onset varied between neonatal period and 15years. Three patients had febrile seizure, 3 patients had myoclonia, and 3 patients had status epilepticus. All patients had abnormal EEG findings except one. There was a slowing of background activity, and generalized discharges were observed in 7 patients; 3 of them had asymmetrical discharges. One patient had right hippocampal sclerosis (HS), and another patient had hypointensities in the basal ganglia and corpus callosum. Reflex features were clinically observed in 3 of the patients; however, EEG results did not show any related findings. One patient had reflex seizures triggered by photic stimuli, hot water, and startling; one by photic stimuli; and the other one by startling. CONCLUSION: Reports on the clinical and electrophysiological features of adult patients with PKU were scant. We emphasized that reflex clinical features may be observed in this metabolic disease, and focal epileptiform abnormalities and asymmetry may be present in electrophysiological evaluation besides the rare association with HS.

Juvenile myoclonic epilepsy and sleep.

Juvenile myoclonic epilepsy (JME) is a sleep-related epilepsy syndrome, and only a few studies have addressed the relationship between JME and sleep disorders. In this review, the sleep characteristics of patients with JME were summarized based on the features of circadian rhythm, the possible cause of the early morning seizures, the common subjective and objective sleep disorders, the alterations in sleep architecture, and the effect of sleep deprivation and sodium valproate (VPA). The aims of this study were to summarize the interaction between JME and sleep, to reveal JME sleep characteristics, to encourage clinicians to focus on JME and sleep, to heighten the positive diagnosis rate, to guide the treatment, to improve the prognosis, and to enhance the daily life quality of patients with JME. At the same time, this study aimed to present existing controversies, in order to necessitate further studies.

Clinical, neuroradiological, and electroencephalographic findings of reflex epilepsies

Background/aim: Reflex seizures are defined as epilepsies with seizures induced by a specific afferent stimulus or patient activity alone or in combination with spontaneous seizures, and/or accompanied by photoparoxysmal response on electroencephalogram (EEG). The aim of this study is to review and analyze clinical, neuroradiological, and EEG findings in reflex epilepsies. Materials and methods: The records of 1598 follow-up patients out of 2237 patients who had been examined between July 1995 and August 2017 were analyzed retrospectively. Results: Eighty of 1598 patients had reflex epilepsy and 72 of those patients had seizures induced by visual stimuli. Considering the somatosensory stimuli, in one patient it was associated with eating while in 7 patients it was associated with hot water. The results of neurological examination were normal in 90% while cranial imaging was normal in 82.5% of the patients. Only 53 of 80 patients' EEGs revealed pathological EEG findings. Furthermore, in 43 patients, the most frequently prescribed drug was valproate. Conclusion: In this hospital-based study, reflex epilepsy frequency was 5% and cranial imaging was mostly found to be normal, as stated in the literature. However, patient histories revealed an unexpectedly high rate of head trauma before seizure onset and a family history of epilepsy.

Genetic background contributes to the co-morbidity of anxiety and depression with audiogenic seizure propensity and responses to fluoxetine treatment.

BACKGROUND: Anxiety and depression are the most frequent comorbidities of different types of convulsive and non-convulsive epilepsies. Increased anxiety and depression-like phenotype have been described in the genetic absence epilepsy models as well as in models of limbic epilepsy and acquired seizure models, suggesting a neurobiological connection. However, whether anxiety and/or depression are comorbid to audiogenic epilepsy remains unclear. The aim of this study was to investigate whether anxiety or depression-like behavior can be found in rat strains with different susceptibility to audiogenic seizures (AS) and whether chronic fluoxetine treatment affects this co-morbidity. METHODS: Behavior in the elevated plus-maze and the forced swimming test was studied in four strains: Wistar rats non-susceptible to AS; Krushinsky-Molodkina (KM) strain, selectively bred for AS propensity from outbred Wistar rats; and a selection lines bred for maximal AS expression (strain "4") and for a lack of AS (strain "0") from KM×Wistar F2 hybrids. Effects of chronic antidepressant treatment on AS and behavior were also evaluated. RESULTS: Anxiety and depression levels were higher in KM rats (with AS) compared with Wistar rats (without AS), indicating the comorbidity with AS. However, in strains "4" and "0" with contrasting AS expression, but with a genetic background close to KM rats, anxiety and depression were not as divergent as in KMs versus Wistars. Fluoxetine treatment exerted an antidepressant effect in all rat strains irrespective of its effect on AS. CONCLUSIONS: Genetic background contributes substantively to the co-morbidity of anxiety and depression with AS propensity.

Alcohol withdrawal in epileptic rats - Effects on postictal depression, respiration, and death.

Patients with epilepsy are at risk of sudden unexpected death in epilepsy (SUDEP). The most common series of events in witnessed cases of SUDEP is a generalized convulsive seizure followed by terminal apnea. Risk factors for SUDEP include prolonged postictal depression (PID), as well as alcohol abuse. The present study examined these issues in a genetic epilepsy model that exhibits generalized convulsive audiogenic seizures (AGSz) but rarely exhibits seizure-induced death, the genetically epilepsy-prone rats (GEPR-9s). We evaluated the effect of ethanol withdrawal (ETX) in GEPR-9s on respiration patterns, duration of PID, and the incidence of seizure-induced death. Audiogenic seizures were induced in GEPR-9s and in normal Sprague-Dawley rats, which were subjected to a 4-day binge ethanol protocol, 18-24h after the last ethanol dose. Following the tonic seizures, all GEPR-9s exhibited PID, characterized by loss of the righting reflex and respiratory distress (RD), which were absent during ETX seizures in the normal rats. During ETX, GEPR-9s exhibited significant increases in the duration of PID and RD, compared with vehicle-treated GEPR-9s. A significant increase in the incidence of death following seizure in GEPR-9s subjected to ETX was observed, compared with that in vehicle-treated GEPR-9s and normal rats subjected to ETX. Death in GEPR-9s was preceded by prolonged seizures because, in part, of the emergence of post-tonic generalized clonus. These results indicate that ETX induced significant increases in the duration of PID and RD, which contributed to the greater incidence of mortality in GEPR-9s compared with that in vehicle-treated GEPR-9s and normal rats. These experiments observed an elevated risk of sudden death associated with alcohol withdrawal in a genetic epilepsy model that had previously been identified as a risk factor in human SUDEP.

Somatosensory reflex seizures in a patient with hypertrophic cranial pachymeningitis.

Somatosensory-evoked reflex epilepsy is characterized by seizures in response to specific stimuli. It is highly uncommon for somatosensory-evoked focal seizures to be caused by movement or a change in posture. Reflex epilepsy induced by both somatosensory and proprioceptive stimulations has not been previously reported. In this study, we present a case of reflex epilepsy evoked by somatosensory and proprioceptive stimulation in a patient with hypertrophic cranial pachymeningitis. After comparing our patient with other cases of previously reported somatosensory-evoked reflex epilepsy, we determined that our patient had an unusual cause of reflex epilepsy.

Effects of age, sex, and sertraline administration on seizure-induced respiratory arrest in the DBA/1 mouse model of sudden unexpected death in epilepsy (SUDEP).

DBA/1 mice are susceptible to audiogenic seizure-induced respiratory arrest (S-IRA), leading to death, which is a model of human sudden unexpected death in epilepsy (SUDEP). Female DBA/1 mice exhibited 71% susceptibility to S-IRA on the third daily test when seizure testing began at postnatal day (PND) 24-30, which was slightly (>10%) but not significantly lower than males. When initial seizure testing was delayed (to >7 weeks of age), DBA/1 mice of both sexes exhibited significantly reduced S-IRA susceptibility, as compared to mice tested initially at PND 24-30. These sex and age issues had not been previously evaluated and may be important for the future use of this SUDEP model. We also observed that 30 min after administering a selective serotonin reuptake inhibitor (SSRI), sertraline (40, 50, or 75 mg/kg i.p.), a significantly reduced S-IRA incidence in DBA/1 mice occurred without blocking seizures, which may be relevant to SUDEP prevention.

Pharmacological and neuroethological studies of three antiepileptic drugs in the Genetic Audiogenic Seizure Hamster (GASH:Sal).

Epilepsy modeling is essential for understanding the basic mechanisms of the epileptic process. The Genetic Audiogenic Seizure Hamster (GASH:Sal) exhibits generalized tonic-clonic seizures of genetic origin in response to sound stimulation and is currently being validated as a reliable model of epilepsy. Here, we performed a pharmacological and neuroethological study using well-known and widely used antiepileptic drugs (AEDs), including phenobarbital (PB), valproic acid (VPA), and levetiracetam (LEV). The intraperitoneal administration of PB (5-20mg/kg) and VPA (100-300mg/kg) produced a dose-dependent decrease in GASH:Sal audiogenic seizure severity scores. The administration of LEV (30-100mg/kg) did not produce a clear effect. Phenobarbital showed a short plasmatic life and had a high antiepileptic effect starting at 10mg/kg that was accompanied by ataxia. Valproic acid acted only at high concentrations and was the AED with the most ataxic effects. Levetiracetam at all doses also produced sedation and ataxia side effects. We conclude that the GASH:Sal is a reliable genetic model of epilepsy suitable to evaluate AEDs.

[The impact of pregnancy and postnatal period on the development of generalized convulsive activity in experiment].

Interrelation between pregnancy and epilepsy is one of the pressing problems of current neurology. Those mechanisms, which suppress or amplify the seizure reactions in pregnancy, have not been yet determined experimentally. The goal of present work was investigation of impact of gestation and the postpartum period on initiation and development of convulsive reactions in the experimental animal model. Epileptic reactions were significantly suppressed during gestation (2 and 3 weeks). The data showed changes in behavioral reactions and EEG seizure activity. In the period of gestation the development of audiogenic kindling in response to repetitive acoustic stimulation is markedly reduced. This indicates the strengthening of inhibitory processes in the brain. It is supposed that in the period of gestation in rats with genetically determined audiogenic seizures excess of sexual hormones and enhancement of GABA-ergic transmission causes marked reduction of development of audiogenic kindling.

Defective visual inhibition in photosensitive idiopathic generalized epilepsy.

PURPOSE: To assess the visual system excitability of photosensitive patients with idiopathic generalized epilepsy (IGE) with the paired-pulse flash-evoked potential (paired F-VEP) technique. METHODS: We studied 19 photosensitive patients with IGE (16 women) showing a photoparoxysmal electroencephalographic (EEG) response (PPR). Twenty-two normal subjects of similar age and sex acted as controls (17 women). We recorded F-VEPs from occipital and central electrodes. Stimuli were single flashes, intermingled to flash pairs at the interstimulus interval (ISI) of 333, 125, 62.5, 50, 33, and 16.5 msec (i.e., at the internal frequency of 3, 8, 16, 20, 30, and 60 Hz). Recordings were done both with closed and open eyes. The single F-VEP was split into a "main complex" and a "late response," which were measured separately. As to paired stimuli, the "test" F-VEP emerged from electronic subtraction of the single F-VEP to the paired F-VEP. Grouped data were analyzed by means of nonparametric analyses of variance (ANOVAs). KEY FINDINGS: In patients, the single F-VEP showed some enhanced components in its early "main complex." Then, the "test" F-VEP behaved differently than controls, particularly if recorded with closed eyes, when the normal inhibition was abolished at given ISIs, corresponding to an internal frequency of 16-30 Hz. In patients with a posterior PPR, impaired inhibition was evident over the occipital region only, but in those with a widespread PPR, it also involved the central areas. SIGNIFICANCE: The paired F-VEP technique documents a defective inhibition in the visual system of photosensitive patients with IGE, whose features and timing likely underlie the PPR origin.

Hot water epilepsy with pachygyria.

Hot water epilepsy (HWE) refers to a specific type of reflex epilepsy precipitated by the stimulus of bathing in hot water. Pathogenesis is still unknown and temporal lobe has been thought to take part in the epileptogenesis. HWE can be symptomatic of focal cortical malformation, and few cases were reported. This is the third report of HEW in which a parietal malformation has been observed. Our hypothesis that sensory cortex might be implicated in the epileptogenic process is corroborated by two previous reports on patients with HWE and malformation of the parietal cortical development.

Electroclinical characterization of epileptic seizures in leucine-rich, glioma-inactivated 1-deficient mice.

Mutations of the LGI1 (leucine-rich, glioma-inactivated 1) gene underlie autosomal dominant lateral temporal lobe epilepsy, a focal idiopathic inherited epilepsy syndrome. The LGI1 gene encodes a protein secreted by neurons, one of the only non-ion channel genes implicated in idiopathic familial epilepsy. While mutations probably result in a loss of function, the role of LGI1 in the pathophysiology of epilepsy remains unclear. Here we generated a germline knockout mouse for LGI1 and examined spontaneous seizure characteristics, changes in threshold for induced seizures and hippocampal pathology. Frequent spontaneous seizures emerged in homozygous LGI1(-/-) mice during the second postnatal week. Properties of these spontaneous events were examined in a simultaneous video and intracranial electroencephalographic recording. Their mean duration was 120 +/- 12 s, and behavioural correlates consisted of an initial immobility, automatisms, sometimes followed by wild running and tonic and/or clonic movements. Electroencephalographic monitoring indicated that seizures originated earlier in the hippocampus than in the cortex. LGI1(-/-) mice did not survive beyond postnatal day 20, probably due to seizures and failure to feed. While no major developmental abnormalities were observed, after recurrent seizures we detected neuronal loss, mossy fibre sprouting, astrocyte reactivity and granule cell dispersion in the hippocampus of LGI1(-/-) mice. In contrast, heterozygous LGI1(+/-) littermates displayed no spontaneous behavioural epileptic seizures, but auditory stimuli induced seizures at a lower threshold, reflecting the human pathology of sound-triggered seizures in some patients. We conclude that LGI1(+/-) and LGI1(-/-) mice may provide useful models for lateral temporal lobe epilepsy, and more generally idiopathic focal epilepsy.

Reflex reading epilepsy: effect of linguistic characteristics on spike frequency.

Reading epilepsy is a rare reflex epilepsy in which seizures are provoked by reading. Several cases have been described in the literature, but the pathophysiological processes vary widely and remain unclear. We describe a 42-year-old male patient with reading epilepsy evaluated using clinical assessments and continuous video/EEG recordings. We administered verbal, nonverbal, and reading tasks to determine factors precipitating seizures. Linguistic characteristics of the words were manipulated. Results indicated that reading-induced seizures were significantly more numerous than those observed during verbal and nonverbal tasks. In reading tasks, spike frequency significantly increased with involvement of the phonological reading route. Spikes were recorded predominantly in left parasagittal regions. Future cerebral imaging studies will enable us to visualize the spatial localization and temporal course of reading-induced seizures and brain activity involved in reading. A better understanding of reading epilepsy is crucial for reading rehabilitation in these patients.

Reflex absence epilepsy induced by gait.

Reflex epilepsy is characterized by seizures that are precipitated by a specific identifiable factor. We describe here the case of a 21-year-old man with notable absence epilepsy since the age of 11 who experienced generalized convulsions 2 years after onset (in the absence of antiepileptic therapy) and reflex absence seizures triggered by walking 7-10 steps. To our knowledge, this case report is the first describing reflex absence epilepsy seizures induced by gait.

Extraoccipital photoparoxysmal response in a case of focal encephalitis.

Photoparoxysmal response (PPR) is commonly associated with idiopathic generalised epilepsies. Most of the focal events induced by intermittent photic stimulation (IPS) are reported to be of occipital origin. Only six temporal lobe epilepsy patients have been reported in the literature with focal PPR at extraoccipital sites. We report a four-year-old girl with possible encephalitis who presented initially with epilepsia partialis continua of limbs on the right side. Interictally, she had left centro-parietal periodic lateralized epileptiform discharges (PLEDs). She responded to medical treatment and was free of seizures and motor and cognitive deficits at six months follow-up. Repeat EEG at follow-up showed left centro-parietal spikes accentuated by IPS. This is the first report of an extraoccipital, extratemporal focus showing PPR. The possible mechanism of PPR from this fronto-parietal epileptogenic focus is discussed.

Anxiety and predisposition to audiogenic epilepsy in rats of different genotypes.

We studied plus-maze behavior of inbred Krushinskii-Molodkina, Wistar, and black-hooded rats (originating from the Long-Evans outbred strain) differing by predisposition to audiogenic seizures. The severity of audiogenic seizures partially correlated with anxiety and negatively correlated with the total level of locomotor activity in the elevated plus-maze. The anxiety parameters in Krushinskii-Molodkina rats were evaluated after injection of anticonvulsant levetiracetam and anxiolytic afobazol. Levetiracetam and afobazol somewhat stimulated locomotor activity.