Female sex steroids and epilepsy: Part 2. A practical and human focus on catamenial epilepsy

Catamenial epilepsy is the best described and most researched sex steroid-specific seizure exacerbation. Yet despite this there are no current evidence-based treatments, nor an accepted diagnostic tool. The best tool we currently have is tracking seizures over menstrual cycles; however, the reality of tracking seizures and menstrual cycles is fraught with challenges. In Part 1 of this two-part review, we outlined the often complex and reciprocal relationship between seizures and sex steroids. An adaptable means of tracking is required. In this review, we outline the extent and limitations of current knowledge on catamenial epilepsy. We use sample data to show how seizure exacerbations can be tracked in short/long and even irregular menstrual cycles. We describe how seizure severity, an often overlooked and underresearched form of catamenial seizure exacerbation, can also be tracked. Finally, given the lack of treatment options for females profoundly affected by catamenial epilepsy, Section 3 focuses on current methods and models for researching sex steroids and seizures as well as limitations and future directions. To permit more informative, mechanism-focused research in humans, the need for both a consistent classification of catamenial epilepsy and an objective biomarker is highlighted.

Cenobamate enhances the anticonvulsant effect of other antiseizure medications in the DBA/2 mouse model of reflex epilepsy

Clinical studies documented that cenobamate (CNB) has a marked efficacy compared to other antiseizure medications (ASMs) in reducing focal seizures. To date, different aspects of CNB need to be clarified, including its efficacy against generalized seizures. Similarly, the pattern of drug-drug interactions between CNB and other ASMs also compels further investigation. This study aimed to detect the role of CNB on generalized seizures using the DBA/2 mouse model. We have also studied the effects of an adjunctive CNB treatment on the antiseizure properties of some ASMs against reflex seizures. The effects of this adjunctive treatment on motor performance, body temperature, and brain levels of ASMs were also evaluated. CNB was able to antagonize seizures in DBA/2 mice. CNB, at 5 mg/kg, enhanced the antiseizure activity of ASMs, such as diazepam, clobazam, levetiracetam, perampanel, phenobarbital, topiramate, and valproate. No synergistic effects were observed when CNB was co-administered with some Na+ channel blockers. The increase in antiseizure activity was associated with a comparable intensification in motor impairment; however, the therapeutic index of combined treatment of ASMs with CNB was more favorable than the combination with vehicle except for carbamazepine, phenytoin, and oxcarbazepine. Since CNB did not significantly influence the brain levels of the ASMs studied, we suggest that pharmacokinetic interactions seem not probable. Overall, this study shows the ability of CNB to counteract generalized reflex seizures in mice. Moreover, our data documented an evident synergistic antiseizure effect for the combination of CNB with ASMs including phenobarbital, benzodiazepines, valproate, perampanel, topiramate, and levetiracetam.

A novel GABRG2 variant in Sunflower syndrome: A case report and video EEG monitoring

OBJECTIVE

Sunflower syndrome is a unique photosensitive epilepsy, characterized by heliotropism and stereotyped seizures associated with handwaving. These handwaving events (HWE) are thought to be an ictal phenomenon, although current data are contrasting. Photosensitive epilepsy occurs in 2%-5% of the epilepsy forms and several pathogenic gene variants have been associated with photosensitive epilepsy. However, the genetic etiology of Sunflower syndrome remains unknown. Antiseizure medications (ASM) efficacious in treating photosensitive epilepsy are valproic acid (VPA) and levetiracetam (LEV) although some forms, such as Sunflower syndrome, can be drug-resistant.

METHODS AND RESULTS

Here, we report an 8-year-old boy with an early onset of episodes of HWE that was initially categorized as behavioral problems for which risperidone was started. However, the medical history was suggestive of Sunflower syndrome, and subsequent video EEG showed focal mostly temporal and frontotemporal (right and left) epileptiform activity and confirmed the epileptic nature of the HWE. Thus, VPA was started and initially led to seizure frequency reduction. Molecular analyses showed a pathogenic variant in GABRG2 (c.1287G>A p.(Trp429Ter)), which has been associated with photosensitive and generalized epilepsy.

SIGNIFICANCE

Overall, clinicians worldwide should be cautious by interpreting HWE and/or other tic-like movements, since an epileptic origin cannot be ruled out. A prompt and correct diagnosis can be made by performing a video EEG early on in the diagnostic process when epileptic seizures are part of the differential diagnosis. Even though the genetic etiology of Sunflower syndrome remains poorly understood, this constellation supports further genetic testing since the detection of a pathogenic variant can help in making correct decisions regarding ASM management.

Management of epilepsy with eyelid myoclonia: Results of an international expert consensus panel

OBJECTIVE

There are limited data about the treatment and management of epilepsy with eyelid myoclonia (EEM). The objective of this study was to determine areas of consensus among an international panel of experts for the management of EEM (formerly known as Jeavons syndrome).

METHODS

An international steering committee was convened of physicians and patients/caregivers with expertise in EEM. This committee summarized the current literature and identified an international panel of experts (comprising 25 physicians and five patients/caregivers). This panel participated in a modified Delphi process, including three rounds of surveys to determine areas of consensus for the treatment, other areas of management, and prognosis for EEM.

RESULTS

There was a strong consensus for valproic acid as the first-line treatment, with levetiracetam or lamotrigine as preferable alternatives for women of childbearing age. There was a moderate consensus that ethosuximide and clobazam are also efficacious. There was a strong consensus to avoid sodium channel-blocking medications, except for lamotrigine, as they may worsen seizure control. There was consensus that seizures typically persist into adulthood, with remission occurring in <50% of patients. There was less agreement about other areas of management, including dietary therapy, lens therapy, candidacy for driving, and outcome.

SIGNIFICANCE

This international expert panel identified multiple areas of consensus regarding the optimal management of EEM. These areas of consensus may inform clinical practice to improve the management of EEM. In addition, multiple areas with less agreement were identified, which highlight topics for further research.

Catamenial epilepsy occurrence and patterns in a mixed population of women with epilepsy

We evaluated the occurrence and distribution of patterns of catamenial epilepsy in a heterogenous cohort of women with epilepsy on no hormonal therapies, enrolled in a prospective, observational study. The primary aim of the study was pregnancy rate in women with epilepsy with no prior reproductive problems. In this analysis, we included women who recorded one or more menstrual cycles with one or more seizures. We measured progesterone concentrations for one to three cycles. We defined catamenial patterns as twofold or greater average daily seizure frequency around menstruation (C1), ovulation (C2), and for anovulatory cycles, from midcycle through menstruation (C3). Twenty-three of the 89 enrolled women with epilepsy were eligible for this analysis; 12 of 23 met criteria for catamenial epilepsy; five of 23 demonstrated only a C1 pattern, two of 23 only a C2 pattern, five of 23 a combined C1/C2 pattern, and the one woman with anovulatory cycles did not demonstrate a C3 pattern. There were no differences in likelihood of demonstrating a catamenial pattern between those who reported a prior catamenial pattern and those who did not (p = .855). This analysis demonstrates the utility of app-based tracking to determine a catamenial pattern. Larger prospective studies could confirm these findings and inform potential therapeutic trial designs for catamenial epilepsy.

Photosensitive Self-Induced Seizures Since Childhood

A 15-year-old girl was admitted to the emergency room because of a bilateral tonic-clonic seizure. The family reported that the episode began with rapid hand movements in front of the patient's eyes while staring at the sun. The patient has a history of multiple admissions in the emergency department due to similar events since the age of eight. Most occurrences were associated with episodes of frustration. The review of the literature has shown that this type of phenomenon, designated in some studies by sunflower syndrome, may be overlooked in patients with photosensitive epilepsy. Despite the unknown etiology, there are several reasons why patients experience this type of behavior, and thus a multidisciplinary approach is needed.

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.

Analysis of gene variants in the GASH/Sal model of epilepsy

Epilepsy is a complex neurological disorder characterized by sudden and recurrent seizures, which are caused by various factors, including genetic abnormalities. Several animal models of epilepsy mimic the different symptoms of this disorder. In particular, the genetic audiogenic seizure hamster from Salamanca (GASH/Sal) animals exhibit sound-induced seizures similar to the generalized tonic seizures observed in epileptic patients. However, the genetic alterations underlying the audiogenic seizure susceptibility of the GASH/Sal model remain unknown. In addition, gene variations in the GASH/Sal might have a close resemblance with those described in humans with epilepsy, which is a prerequisite for any new preclinical studies that target genetic abnormalities. Here, we performed whole exome sequencing (WES) in GASH/Sal animals and their corresponding controls to identify and characterize the mutational landscape of the GASH/Sal strain. After filtering the results, moderate- and high-impact variants were validated by Sanger sequencing, assessing the possible impact of the mutations by “in silico” reconstruction of the encoded proteins and analyzing their corresponding biological pathways. Lastly, we quantified gene expression levels by RT-qPCR. In the GASH/Sal model, WES showed the presence of 342 variations, in which 21 were classified as high-impact mutations. After a full bioinformatics analysis to highlight the high quality and reliable variants, the presence of 3 high-impact and 15 moderate-impact variants were identified. Gene expression analysis of the high-impact variants of Asb14 (ankyrin repeat and SOCS Box Containing 14), Msh3 (MutS Homolog 3) and Arhgef38 (Rho Guanine Nucleotide Exchange Factor 38) genes showed a higher expression in the GASH/Sal than in control hamsters. In silico analysis of the functional consequences indicated that those mutations in the three encoded proteins would have severe functional alterations. By functional analysis of the variants, we detected 44 significantly enriched pathways, including the glutamatergic synapse pathway. The data show three high-impact mutations with a major impact on the function of the proteins encoded by these genes, although no mutation in these three genes has been associated with some type of epilepsy until now. Furthermore, GASH/Sal animals also showed gene variants associated with different types of epilepsy that has been extensively documented, as well as mutations in other genes that encode proteins with functions related to neuronal excitability, which could be implied in the phenotype of the GASH/Sal. Our findings provide valuable genetic and biological pathway data associated to the genetic burden of the audiogenic seizure susceptibility and reinforce the need to validate the role of each key mutation in the phenotype of the GASH/Sal model.

Suppression of the photoparoxysmal response in photosensitive epilepsy with cenobamate (YKP3089)

OBJECTIVE

To evaluate the effect of cenobamate in patients with photoparoxysmal-EEG response (PPR) to intermittent photic stimulation (IPS) as proof of principle of efficacy in patients with epilepsy.

METHODS

In this multicenter, single-blind study, adults with photosensitive epilepsy, with/without concomitant antiepileptic drug therapy, underwent IPS under 3 eye conditions after a single dose of placebo (day -1, day 2) or cenobamate (day 1; 100, 250, or 400 mg). Complete suppression was a standardized photosensitivity range reduction to 0 over ≥1 time points for all eye conditions. Partial suppression was a ≥3-point reduction over ≥3 testing times vs the same time points on day -1 in ≥1 eye condition. Pharmacokinetics and safety were assessed.

RESULTS

Of 6 evaluable patients, 5 reentered to receive higher doses. Cenobamate 100 mg produced partial suppression in 1 of 3 patients; 250 mg produced complete suppression in 1 of 4 and partial suppression in 4 of 4 patients; and 400 mg produced complete suppression in 1 of 4 and partial suppression in 2 of 4 patients. PPR was consistently reduced on days 1 and 2 (>24 hours after cenobamate) vs day -1 (placebo) with the 250- and 400-mg doses. Area under the plasma concentration-time curve (before dose to last measurable concentration) values between 201 and 400 μg/h/mL resulted in partial suppression in 4 of 6 (66%) patients. Most common adverse events were dizziness and somnolence.

CONCLUSIONS

This proof-of-principle study demonstrated that cenobamate is a potentially effective product for epilepsy.

CLINICALTRIALSGOV IDENTIFIER

NCT00616148.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that, for patients with photosensitive epilepsy, cenobamate suppresses IPS-induced PPR.

Study of Uridine Effect on the Development of Audiogenic Tonic Seizures in Krushinsky-Molodkina Strain Rats

The latency of tonic seizure in response to loud sound (in rats of the Krushinsky-Molodkina strain with audiogenic epilepsy) had been slightly (although statistically significantly) longer after chronic uridine injections (100 mg/kg, i.p., three times a day during 9 or 12 days). The recovery time from the tonic seizure was shorter after 12 days of injections in comparison to the 9-day injection period. At the same time, the intensity of tonic seizures provoked by loud sound did not change after chronic uridine injections. The lack of uridine anticonvulsive effect demonstrated in the audiogenic epilepsy model contradicts the anticonvulsant effects of uridine in experiments with other seizure models, in which the epileptic foci were localized in the forebrain structures.

Features of stimulus-specific seizures in dogs with reflex epilepsy: 43 cases (2000-2014)

OBJECTIVE To describe the occurrence and management of reflex epilepsy (ie, seizure activity triggered by exposure to specific locations or situations) in dogs. DESIGN Retrospective case series. ANIMALS 43 client-owned dogs. PROCEDURES Discussions by veterinarians participating in the Veterinary Information Network online community for the years 2000 through 2014 were reviewed to identify dogs with a diagnosis of reflex epilepsy and seizure activity in response to stimuli. History, signalment (including age at onset), the specific stimulus or stimuli that provoked seizures, treatments, and any concurrent neurologic diagnoses were recorded. RESULTS A variety of breeds were affected. Median age at onset was 5 years (range, 3 months to 11 years). Reflex seizures were reported as being repeatedly triggered by visits to a veterinary clinic (35/43 dogs), grooming facility (24/43 dogs), or boarding facility (13/43 dogs) and, less commonly, by other situations (eg, pet store or car ride). Over half of the dogs (24/43) had multiple triggers. Eight (19%) dogs had seizures at other times that were not induced by location or a specific situation. A variety of sedatives and maintenance antiepileptic drugs administered to affected dogs failed to prevent the stimulus-specific seizure activity. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study suggested that seizures provoked by specific situations or locations occur in dogs with reflex epilepsy and that common triggers were visits to veterinary and grooming facilities. Further studies are necessary to elucidate the characteristics of reflex epilepsy in dogs and to determine the most effective means to manage these patients.

Neonatal Eating Epilepsy: Pathophysiological and Pharmacologic Aspects

We report a case of neonatal Eating Epilepsy. The baby was admitted to the Neonatal Intensive Care Unit of Chieti after delivery, with respiratory distress syndrome. In the first day of life the baby had an episode of arterial desaturation and cyanosis with EEG alterations. After laboratory and instrumental investigations we found a correlation between EEG abnormalities and GER. So we administered a combination of anticonvulsive and antacid therapy and, considering the total improvement of EEG, we diagnosed a neonatal form of “eating epilepsy”.

Effects of marketed antiepileptic drugs and placebo in the human photosensitivity screening protocol

A study of epilepsy patients with a reproducible range of photoparoxysmal responses (PPR) (epileptiform discharges evoked by flashing lights) has been used as a "proof-of-concept" trial to determine if novel potential antiepileptic drugs (AEDs) should proceed in development. The standard design for this trial requires a 3-day inpatient stay and is single-blind. We evaluated two marketed and effective AEDs-one narrow-spectrum [carbamazepine (CBZ)], and one broad-spectrum [levetiracetam (LEV)]-using a novel double-blinded, cross-over outpatient version of the trial to detect acute drug effects of the two marketed AEDs on photosensitivity. We tested 6 patients with a known stable photosensitivity response, using single oral doses of CBZ 400 mg and LEV 1000 mg, compared to 2 test days with single placebo doses. Patients who received LEV had the lowest mean PPR (compared with placebo and CBZ). The mixed effect model showed a significant effect of LEV in all eye closure conditions (p < 0.001). There was no evidence of a significant change in PPR after CBZ or placebo treatment. In conclusion, LEV 1000 mg, but not CBZ 400 mg, was effective in suppressing photosensitivity within a 6-h period compared with placebo showing the ability of our novel photosensitivity trial design to demonstrate effects of broad-spectrum AEDs. We cannot confirm the ability of the photosensitivity trial to detect the narrow-spectrum AED CBZ in our design. The novel outpatient study design is feasible and is expected to reduce costs compared with previous methodology.

Reflex myoclonic epilepsy in infancy: a critical review

Benign myoclonic epilepsy in infancy, classified among the generalised idiopathic epilepsies, is characterised by the occurrence of myoclonic seizures in the first three years of life in otherwise normal infants. Some authors have described cases of myoclonic seizures as a reflex response to sudden unexpected tactile or acoustic stimuli and this clinical entity has been proposed as a separate nosographic syndrome, referred to as "reflex myoclonic epilepsy in infancy" (RMEI). We reviewed all published articles and case reports on RMEI in order to clarify clinical and electroencephalographic findings, with particular attention to outcome and treatment. RMEI appears to be a benign variant of idiopathic myoclonic epilepsy in infancy with specific features that occur in neurologically and developmentally normal children. This rare clinical entity is often under-described and under-diagnosed, and for this reason should be brought to the attention of paediatricians in order to avoid extensive investigations and reassure parents of the lack of long-term complications.

[The effect of ionotropic glutamate receptor antagonist on pentylenetetrazole-indused seizures in Krushinsky-Molodkina rats]

Krushinsky-Molodkina (KM) rats exhibit inherited susceptibility to audiogenic seizures and auditory stimuli induce generalized tonic-clonic seizures that resemble human epilepsy. The aim of this study was to compare the neurological manifestations of pentylenetetrazole (PTZ)-induced seizures in Wistar and KM rats to clarify the contribution of inherited susceptibility to audiogenic seizures, and to assess the anticonvulsant activity of NMDA receptor blockers memantine and IEM-1921 (1-phenylcyclohexylamine) in the PTZ-induced seizure model in KM rats. KM rats exhibited increased seizure severity relative to Wistar rats, and the death of KM rats was observed in 2.1 times more likely. Both NMDA receptor blockers showed anticonvulsant activity in the PTZ-induced seizure model, however IEM-1921 was more potent than memantine. IEM-1921 reduced the average intensity of the seizures by 2 points on a 5-point scale, and the total duration of generalized seizures was decreased by 41 times. IEM-1921 completely prevented the death of animals, while memantine only slightly decreased the mortality (68% in control conditions vs. 50% with administration of memantine). The results of the present study suggest that NMDA receptors are involved in the molecular mechanisms of seizures of different etiologies.

[Effects of ionotropic glutamate receptor channel blockers ON sleep-waking organization in rats]

The effects of non-competitive glutamate receptor antagonists on sleep-waking organization have been studied on Krushinskii-Molodkina rats having an inherited predisposition to audiogenic seizures and Wistar ones which are resistant to this action of sound. Two types of blockers of glutamate receptor open channels were used: selective blockers of NMDA receptors (memantine and IEM-1921) and blockers of mixed type, impacting both on the NMDA and Ca-permeable AMPA/ kainate receptors (IEM-1754 and IEM 1925). During the first 3 hours after administration of these glutamate antagonists the total or partial deprivation of fast-wave sleep was provoked. Additionally the selective NMDA receptor blocking drugs (memantine, IEM-1921) induced in the same period a significant increase of the representation of wakefulness at the cost of reducing of the total time of slow-wave sleep. These effects are most likely to be a consequence of the blockade of NMDA receptors responsible for the launch and maintenance of wakefulness, slow- and fast-wave sleep. In the same first 3 hours period after the administration of IEM-1754 and IEM-1925 the organization of sleep was not significantly affected. The evident reduction of wakefulness, total duration and increase of slow-wave sleep impact was observed, during the second three-hour period. It, apparently, can be caused by the blockade of AMPA/kainate receptors. The obtained results indicate the involvement of NMDA and AMPA/kainate receptors in the functioning of various parts of the sleep system of rats belonging to both lines.

[Effects of ionotropic glutamate receptor channel blockers on the development of audiogenic seizures in Krushinski-Molodkina rats]

The action of noncompetitive blockers of glutamate receptors has been investigated on Krushinski-Molodkina rats genetically-prone to audiogenic seizures. The selective blockers of NMDA receptor channels, memantine and IEM-1921, and their dicationic homologues, IEM-1925 and IEM-1754, capable of blocking in varying degrees both NMDA and Ca-permeable AMPA receptor channels, were studied. The drugs were injected intramuscularly to rats with the different time intervals (30 min, 1, 2 or 3 hours) before sound signal. The effects of the drugs on latent period of initial locomotor activity provoked by audio stimulation (8 kHz sine-wave tone, 90 dB volume), the appearance of clonic convulsions of different intensities, and, finally, tonic convulsions with limb and tail extension were evaluated. Within 30 min after injection IEM-1921 at a dose of 5 mg/kg, 33% of rats manifested a complete absence of convulsive reactions to sound, and in 59% of rats audiogenic seizures occured only in the form of motor excitation without a generalized clonic-tonic convulsions. Memantine at a dose of 5 mg/kg did not cause a complete blockade of seizures, but after 1 h of injection in 50% of the rats and after 2 h in 70% of rats a weakening of the audiogenic seizures to the level of motor excitation only was observed. After 3 hrs after administration of blockers its anticonvulsive action weakened significantly (p < 0.01). Dicationic blockers that block both NMDA and AMPA/kainate receptors, IEM-1925 (in doses of 0.001-20.0 mg/kg) and IEM-1754 (0.025-50.0 mg/kg), did not affect audiogenic clonic-tonic convulsive reactions. The involvement of activation of NMDA and calcium permeable AMPA/kainate receptors in the pathogenesis of audiogenic seizures is discussed.

Flicker Illness: An Underrecognized but Preventable Complication of Helicopter Transport

A case report of seizure due to photic stimulation from sunlight shining through spinning helicopter rotor blades is discussed. A review of photosensitive epilepsy is provided with particular emphasis on the effects and frequencies of photic stimulation required to induce symptoms. The frequencies of flashing light produced by spinning helicopter rotor blades commonly used in air medical transport range from 24 to 27 flashes per second. These frequencies are well within the range reported in the literature to produce symptoms in the laboratory setting. The literature provides only a few case reports of individuals sustaining a seizure after photic stimulation from spinning turboprop or helicopter blades. Symptoms range from mild discomfort and headache to profound spatial disorientation and seizures and may be an underrecognized but preventable complication of air medical transport.

Television-provoked epilepsy in children: a follow-up survey from Isfahan, Iran

BACKGROUND

Television as an external stimulation can precipitate epileptic seizures. Today this kind of epilepsy is known as television epilepsy. As children spend much of their time watching television, it is important to study this type of epilepsy in this age group. This study was designed to describe the clinical and some demographic characteristics of television epilepsy in Iranian children.

METHODS

Patients who were diagnosed as having television epilepsy with an age less than 12 years were recruited from outpatient neurology clinics in Isfahan, Iran, from September 2002 through September 2006. We collected the case-related information including electroencephalograms, radiologic findings, and patients' history.

RESULTS

Thirty patients with television epilepsy with the age less than 12 years were identified. Of whom 17 (56.7%) were females and 13 (43.3%) were males. The mean age at the onset of seizure was 9.9+/-2.1 years. Children had absence (3.3%), myoclonic (3.3%), and generalized tonic-clonic (93.3+/-) seizures in response to intermittent photic stimulations. Interictal epileptiform discharges in electroencephalograms were detected in 83.3%. In addition, neuroimaging findings were normal in 96.7% of the patients. In our study, 56.7% of the children had pure television epilepsy and 43.3% experienced other types of generalized seizure. During the follow-up period after initiation of variable drug treatments including valproic acid, carbamazepine, phenobarbital, clonazepam, ethosuximide, and lamotrigine all the patients had complete seizure remission.

CONCLUSION

The clinical and demographic differences of our patients compared with other reports are probably due to genetic differences. In our study, it was demonstrated that carbamazepine could be used in children with television epilepsy because it had successfully terminated seizures in 43.3% of the patients.

[The investigation of cataleptic muscle tonus changes in rats after audiogenic seizures]

The duration and severity of cataleptic freezing after audiogenic seizures were investigated in rats of several genotypes with different predisposition to audiogenic epilepsy. These genotypes were the Krushinsky-Molodkina strain (KM--the audiogenic seizure prone strain), the Wistar and two new substrains selected from hybrids KM x Wistar for high ("4") and low ("0") audiogenic seizure susceptibility. The drug injections, which modulated the audiogenic fit severity, induced the changes in catalepsy too. It was found, that in intact animals cataleptic freezing developed after audiogenic seizures only and was more intense after severe seizures, the correlation coefficient being statistically significant. Levetiracetam (anticonvulsant drug) injections resulted in significant decrease of audiogenic fit severity and cataleptic state in Wistar and KM rats. Caffeine injections resulted in audiogenic seizures accompanied by cataleptic freezing in rats of the substrain "0", selected for audiogenic non-pronness.

Seizures induced by the sight of moving water

The most frequent precipitants of photic- or pattern-induced seizures are television and discotheque lighting effects. Seizure induction by reflection of bright sunlight on water surfaces has also been reported. We report a patient with seizures induced by the sight of moving water in the absence of bright sunlight. [Published with video sequences].

ANTICONVULSANT, BUT NOT ANTIEPILEPTIC, ACTION OF VALPROATE ON AUDIOGENIC SEIZURES IN METAPHIT?TREATED RATS

1. The blocking effects of valproate (2-propylpentanoic acid), a standard anti-epileptic drug, on metaphit (1-[1-(3-isothiocyanatophenyl)-cyclohexyl]-piperidine)-induced audiogenic seizures as a model of generalized, reflex audiogenic epilepsy in adult Wistar male rats were studied. 2. Rats were stimulated using an electric bell (100 +/- 3 dB, 5-8 kHz, 60 s) 60 min after i.p. metaphit (10 mg/kg) injection and afterwards at hourly intervals. For power spectra and electroencephalograph (EEG) recordings, three gold-plated screws were implanted into the skull. Different doses of valproate (50, 75 and 100 mg/kg) were injected i.p. into rats with fully developed metaphit seizures after the eighth audiogenic testing. 3. In metaphit-treated animals, the EEG appeared as polyspikes, spike-wave complexes and sleep-like patterns, whereas the power spectra were increased compared with the corresponding controls. 4. Valproate reduced the incidence and intensity of convulsions and prolonged the duration of the latency period in a dose-dependent manner 4 h after administration. 5. The ED(50) of valproate in the first hour after injection was 63.19 mg/kg (95% confidence interval 51.37-77.71 mg/kg). 6. None of the doses of valproate applied eliminated the EEG signs of metaphit-provoked epileptiform activity. 7. Taken together, these results suggest that all doses of valproate examined acted to suppresse behavioural but not epileptic EEG spiking activity in metaphit-induced seizures.

Evaluation of brivaracetam, a novel SV2A ligand, in the photosensitivity model

OBJECTIVE

To assess the activity of brivaracetam, a novel SV2A ligand, in the photosensitivity model as a proof-of-principle of efficacy in patients with epilepsy.

METHODS

A subject-blind placebo-controlled study in patients with photosensitive epilepsy was performed to investigate the effect of single-dose brivaracetam (10, 20, 40, or 80 mg) on photosensitive responses. Each patient was exposed to intermittent photic stimulation that evoked a generalized photoparoxysmal EEG response. Individual standard photosensitivity ranges (SPRs) were recorded post-placebo (day -1) and post-brivaracetam until return to baseline (day 1 to 3). Plasma concentrations of brivaracetam and any concomitant antiepileptic drugs were determined.

RESULTS

Of the 18 evaluable patients, none achieved SPR abolishment post-placebo, whereas 14 (78%) achieved complete abolishment post-brivaracetam. Decrease in SPR was seen in 8 patients (44%) post-placebo compared to 17 (94%) post-brivaracetam. Duration of response was twice as long post-brivaracetam 80 mg (59.5 hours) compared with lower doses, although the overall effect was not dose-dependent. Time to maximal photosensitive response was dose-related with the shortest time interval observed at the highest dose (0.5 hours post-brivaracetam 80 mg). The area under the effect curve (SPR change from pre-dose vs time) appeared linearly correlated with the area under the plasma concentration curve. Brivaracetam was well tolerated. The most common adverse events were dizziness and somnolence.

CONCLUSIONS

Our findings show that brivaracetam clearly suppresses generalized photoparoxysmal EEG response. As such, investigations of the antiepileptic properties and tolerability of brivaracetam are warranted in further clinical studies of patients with epilepsy.

A case with atypical childhood occipital epilepsy "Gastaut type": an ictal migraine manifestation with a good response to intravenous diazepam

We report the history of a 14-year-old girl with atypical childhood occipital epilepsy "Gastaut type" whose first generalized tonic-clonic seizure was preceded by migraine without aura and followed by a status migrainosus. This status lasted for 3 days despite standard analgesic therapy. An EEG recording revealed an occipital status epilepticus during her migraine complaints. Seven minutes after intravenous administration of 10 mg diazepam under continuous EEG recording, a suppression of the epileptiform discharges over the right occipital was seen, while the headache subsided 3 min later. After precise questioning about the circumstances that possibly could have led to these events, it appeared that she had played for hours with a play station on the new color TV and she had visited an exhibition of Matisse and Bonnard with bright colors and contrast-rich text. Standardized extensive intermittent photic stimulation (IPS), 2 days after the status migrainosus, evoked besides asymmetrical right-sided driving, green spots in her left visual field, while in the EEG sharp waves were recorded over the right parietotemporal region. After further IPS with 20 Hz (eye closure), she started complaining of a light pulsating headache right occipitally and in the EEG right parietotemporal sharp-waves were seen. This lasted for about 10 min. Later, an interictal routine EEG was normal except for some theta over the right temporooccipital area. The most likely diagnosis is an atypical form of occipital epilepsy "Gastaut type." We would therefore advocate recording EEGs with photic stimulation in patients with atypical migraneous features.

Influence of levetiracetam on the anticonvulsant efficacy of conventional antiepileptic drugs against audiogenic seizures in DBA/2 mice

Levetiracetam (LEV, [S]-alpha-ethyl-2-oxo-1-pyrrolidine acetamide) is a new antiepileptic that has been used as adjunctive therapy to treat patients with intractable epilepsy. Systemic administration of levetiracetam (2.5-30 mg/kg, intraperitoneally (i.p.)) was able to produce a dose-dependent decrease in DBA/2 audiogenic seizure severity score. In combination with conventional antiepileptic drugs, levetiracetam, 5mg/kg, i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of some antiepileptic drugs studied against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by levetiracetam was greater, approximately twice, for carbamazepine, diazepam, felbamate, topiramate, gabapentin, and valproate, less for lamotrigine, phenobarbital and phenytoin. This increase was associated with a comparable impairment in motor activity; however, the therapeutic index of combined treatment of antiepileptic drugs with levetiracetam was more favourable than the combination with saline with the exception of lamotrigine, phenytoin and phenobarbital. Since levetiracetam did not significantly influence the total and free plasma and the brain levels of antiepileptics studied. In addition, levetiracetam did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, levetiracetam showed an additive anticonvulsant effect when administered in combination with some classical anticonvulsants, most notably carbamazepine, diazepam, felbamate, gabapentin, topiramate and valproate, implicating a possible therapeutic relevance of such drug combinations.

Photosensitive Benign Myoclonic Epilepsy in Infancy

PURPOSE

To describe the electroclinical features of subjects who presented with a photosensitive benign myoclonic epilepsy in infancy (PBMEI).

METHODS

The patients were selected from a group of epileptic subjects with seizure onset in infancy or early childhood. Inclusion criteria were the presence of photic-induced myoclonic seizures and a favorable outcome. Cases with less than 24 month follow up were excluded from the analysis.

RESULTS

Eight patients were identified (4 males, 4 females). Personal history was uneventful. All of them had familial antecedents of epilepsy. Psychomotor development was normal in 6 cases, both before and after seizure onset. One patient showed a mild mental retardation and a further patient showed some behavioral disturbances. Neuroradiological investigations, when performed (5 cases), gave normal results. The clinical manifestations were typical and could vary from upward movements of the eyes to myoclonic jerks of the head and shoulders, isolated or briefly repetitive, never causing a fall. Age of onset was between 11 months and 3 years and 2 months. Characteristically, the seizures were always triggered by photic stimulation. Non photo-induced spontaneous myoclonic attacks were reported in 2 cases during the follow-up. Other types of seizures were present at follow-up in 2 cases. The outcome was favorable, even if, usually, seizure control required high AED plasma levels. Since the clinical symptoms were not recognized early, some patients were treated only many years after the onset of symptoms.

CONCLUSION

Among BMEI patients, our cases constitute a subgroup in which myoclonic jerks were always triggered by photostimulation, in particular at onset of their epilepsy.

Long-Term Outcome of Pattern-Sensitive Epilepsy

PURPOSE

To evaluate the long-term outcome of patients with pattern-sensitive epilepsy.

METHODS

We prospectively studied 35 patients (21 females and 14 males) with pattern-sensitive epilepsy (follow up > or = 5 years; mean 13.9; range 6.4 - 27.6). All cases had regular clinical examinations and serial electroencephalographic (EEG) recordings. Photosensitivity and pattern sensitivity were ascertained neurophysiologically in all cases. Outcome was evaluated according to the following variables: duration of photosensitivity, rate of remission (seizure-free period > or = 2 years), withdrawal of therapy, and recurrence after drug discontinuation.

RESULTS

The epilepsy was generalized in 18 cases (17 idiopathic, one symptomatic) and partial in 17 (13 idiopathic, four symptomatic). Sixteen patients (46%) had a family history of seizures. The mean age at the last examination was 21.4 years (range 11.2-35.5 years). Five patients (14%) had only reflex seizures. The most common type of spontaneous seizures was generalized (60%), whereas reflex seizures were more frequently partial (74%). Mean epilepsy duration was 8.7 +/- 6.3 years. Patients with only reflex seizures were instructed to avoid precipitating stimuli and were not treated with antiepileptic drugs. Treatment was gradually withdrawn in 10 out of 30 treated patients, with relapse in only two cases. At the end of follow up, 28 patients (80%) were seizure-free.

CONCLUSION

The long-term outcome of patients with pattern-sensitive epilepsy indicates a good prognosis with a favorable course for both spontaneous and reflex seizures.

EEG wavelet analyses of the striatum–substantia nigra pars reticulata–superior colliculus circuitry: Audiogenic seizures and anticonvulsant drug administration in Wistar audiogenic rats (War strain)

The importance of the substantia nigra pars reticulata (SNPr), striatum (STR) and superior colicullus (SC) in the blockade of experimental seizures is well known. But, in audiogenic seizures (brainstem tonic-clonic seizures), the anticonvulsant activity of these nuclei is still controversial. In the present study we aimed to analyze the STR-SNPr-CS circuitry in the audiogenic seizures of Wistar audiogenic rat (WAR). Behavioral and electroencephalographic (EEG) data were collected from WARs under no treatment or injection with systemic (phenobarbital) or intracerebral (intranigral) drugs (muscimol and phenobarbital). The main EEG frequency oscillation of STR, SNPr and SC seen before, during and after audiogenic seizures or during seizure protection, was determinated with wavelet spectral analyses. This method allows the association between behavior and EEG (video-EEG). Audiogenic seizures last only for half a minute in average, suggesting that the interruptions of seizures are probably not due to exhaustion. Systemic phenobarbital caused an acute and dose-dependent behavioral and EEGraphic anticonvulsant effect both in WARs. The dose of phenobarbital 15mg/kg protected animals almost completely, without side effects such as ataxia and sedation. In our data, this endogenous "natural" seizure blockade (or termination) seems to be similar to the "forced" seizure abolition, like the one caused by a systemic non-ataxic phenobarbital dose, because in both cases an intense decrease in the EEG main frequency oscillation can be seen in SNPr and SC. Intranigral phenobarbital or muscimol did not protect animals, and actually induced an increase in the main EEG frequency oscillation in SC. The main finding of the present study is that, in contrast to what is well believed about the incapacity to control audiogenic seizures by the striato-nigro-tectal circuitry, we collected here evidences that these nuclei are involved in the ability to block these seizures. However, the striato-nigro-tectal circuitry in WARs, a genetically developed strain, seems to have different functional mechanisms when compared with normal rats.

Role of valproate across the ages. Treatment of epilepsy in children

In June 2005 a team of experts participated in a workshop with the objective of reaching agreement on the place of valproate use in the treatment of paediatric epilepsy patients. A general "consensus of the meeting" was that the initiation of antiepileptic drug (AED) treatment should be based on a seizure-syndromic approach in children. Participants of the meeting also agreed that valproate is currently the AED with the broadest spectrum across all types of seizures and syndromes. Its superiority has been shown over almost 40 years of clinical experience. The best results are seen in idiopathic generalized epilepsy with or without photosensitivity, idiopathic focal and symptomatic generalized tonic-clonic seizures (GTCS). Evidence supports the use of valproate, ethosuximide and lamotrigine in absence epilepsies and the use of carbamazepine, lamotrigine, oxcarbazepine, phenytoin, topiramate, valproate and phenobarbital for primary GTCS. For new AEDs trials have been undertaken to define their therapeutic role but studies comparing their role to 'old' broad-spectrum drugs in specific syndromes are missing. Experts concluded that intravenous (i.v.) valproate is a useful agent in the treatment of non-convulsive status epilepticus (SE). There is an easy transition to oral treatment following i.v. valproate use. The discussion also concluded that, despite the lack of studies, valproate is an interesting, underutilized alternative in convulsive SE but more controlled studies are needed. The side effects of valproate use are well documented. Its effect on cognition and behaviour is more favourable than many of the other AEDs which is an important consideration in children. Overall, the clinical consensus of the meeting was that valproate's well established therapeutic properties far outweigh the negative side effects. Contraindication or withdrawal should be assessed individually.

Delta-Sleep-Inducing Peptide Potentiates Anticonvulsive Activity of Valproate against Metaphit-Provoked Audiogenic Seizure in Rats

The effect of delta-sleep-inducing peptide (DSIP) on the anticonvulsive activity of a nonprotective valproate (VPA) dose in a metaphit model of generalized, reflex audiogenic seizures in adult Wistar rats was studied. The animals that received metaphit (10 mg/kg) were exposed to audiogenic stimulation (100 +/- 3 dB, 60 s) at hourly intervals. Metaphit-treated rats displaying seizures in 8 previous tests were i.p. injected with VPA (50 mg/kg) or DSIP (1.0 mg/kg) or their combination. Latency to seizure was behaviorally assessed. The EEGs and power spectra were recorded and analyzed. Neurotoxicity was evaluated by the chimney test. DSIP or VPA alone expressed no significant effect on the latency duration, but their combination significantly prolonged latency to seizure during 6 h after injection, while inducing no significant motor impairment. Neither the applied drugs nor their combination abolished metaphit-provoked EEG epileptiform activity. The results show that DSIP potentiated anticonvulsive effects of a nonprotective VPA dose in a metaphit model of audiogenic seizures without influencing its neurotoxicity.

Acute and chronic tianeptine treatments attenuate ethanol withdrawal syndrome in rats

Effects of acute and chronic tianeptine treatments on ethanol withdrawal syndrome were investigated in rats. Ethanol (7.2% v/v) was given to adult male Wistar rats by a liquid diet for 30 days. Acute or chronic (twice daily) tianeptine (5, 10 and 20 mg/kg) and saline were administered to rats intraperitoneally. Acute and last chronic tianeptine injections and saline were done 30 min before ethanol withdrawal testing. After 2nd, 4th and 6th hours of ethanol withdrawal, rats were observed for 5 min, and withdrawal signs which included locomotor hyperactivity, agitation, tremor, wet dog shakes, stereotyped behavior and audiogenic seizures were recorded or rated. Locomotor activity in naive (no ethanol-dependent rats) was also tested after acute tianeptine treatments. Acute but not chronic tianeptine treatment attenuated locomotor hyperactivity and agitation in ethanol-dependent rats. Both acute and chronic tianeptine treatment produced some significant inhibitory effects on tremor, wet dog shakes, stereotyped behaviors and audiogenic seizures during the ethanol withdrawal. Our results suggest that acute or chronic tianeptine treatment attenuates ethanol withdrawal syndrome in ethanol-dependent rats and this drug may be useful for treatment of ethanol-type dependence.

Language-induced Epilepsy, Acquired Stuttering, and Idiopathic Generalized Epilepsy: Phenotypic Study of One Family

PURPOSE

Language-induced epilepsy involves seizure precipitation by speaking, reading, and writing. Seizures are similar to those of reading epilepsy (RE). The nosologic position of language-induced epilepsy is not clear. We performed a clinical and neurophysiological study in a multigenerational family with the association of idiopathic generalized epilepsy (IGE) with ictal stuttering as a manifestation of reflex language-induced epilepsy.

METHODS

Nine members on three generations were studied. All patients underwent video-polygraphic EEG recordings (awake and during sleep). A standardized protocol was applied to test the effect of language and non-language-related tasks.

RESULTS

Six patients presented language-induced jaw jerking that mimicked stuttering and corresponded to focal myoclonus involving facial muscles. This was associated with an IGE phenotype in four of these patients. Focal EEG spikes were found in all six patients by visual analysis and/or back-averaging techniques. The focal spikes were either asymptomatic (when followed by a slow wave) or symptomatic of facial myoclonia (when isolated). Levetiracetam, used as add-on or monotherapy in four patients, suppressed ictal stuttering. One additional case only had a phenotype of IGE without focal features.

CONCLUSIONS

This family study demonstrates the phenotypic heterogeneity of the association of IGE phenotype with ictal stuttering (language-related reflex seizure). Our data suggest that this particular form of reflex epilepsy related to language has more similarities with generalized epilepsies than with focal ones. Neurophysiological investigations should be performed more systematically in patients with acquired stuttering, especially if there is family history of IGE.

Game-related seizures presenting with two types of clinical features

We evaluated 22 patients with epileptic seizures in which the seizures were triggered by various games or game-related materials. Based on whether spontaneous seizure coexisted or not, these 22 patients were divided into two groups. Ten patients who experienced seizures exclusively while playing or watching specific games were referred to as Group I, while 12 patients that had both game-induced and spontaneous seizures were classified as Group II. The patients in Group I had a middle-age onset (39.1 years) with a male predominance (90%). The electroencephalogram (EEG) or brain magnetic resonance imaging revealed non-specific abnormalities in 60%, and the partial onset seizure was recognized in 30% of patients. Antiepileptic drugs had uncertain benefits in this group. In Group II, patients had a male predominance (67%), with onset during adolescence (16.3 years). Most of them had generalized tonic-clonic seizures, myoclonic seizures, and absences, and 42% showed epileptiform discharge on EEG. These 12 patients were categorized into idiopathic generalized epilepsies. Although photosensitivity was an important factor, higher mental activity seemed to be significant precipitants of seizures in Group II. Antiepileptic drugs were necessary and valproic acid alone or combined with clonazepam was effective in this group. The results showed that game-related seizures are not a unique and homogeneous syndrome and may consist of different mechanisms. Teenage onset, coexistent spontaneous seizure, and associated idiopathic generalized epilepsies were crucial factors in the determination of antiepileptic drug therapy. Moreover, avoiding the related games altogether may be a more productive preventive measure.

Reflex seizures and reflex epilepsy

Reflex seizures are evoked by a specific afferent stimulus or by activity of the patient and are divided into those characterized by generalized seizures and those principally manifested by focal seizures. Reflex epilepsies are syndromes in which all epileptic seizures are precipitated by sensory stimuli. Three categories of reflex seizures encountered clinically include pure reflex epilepsies, reflex seizures that occur in generalized or focal epilepsy syndromes that are also associated with spontaneous seizures, and isolated reflex seizures occurring in situations that do not necessarily require a diagnosis of epilepsy. Generalized reflex seizures are precipitated by visual light stimulation, thinking, and decision making. These seizures usually respond to valproate treatment. Numerous triggers can induce focal reflex seizures. The triggers include reading, writing, other language functions, startle, somatosensory stimulation, proprioception, auditory stimuli, immersion in hot water, eating, and vestibular stimulation. The classification and characteristics of reflex seizures and epilepsies are described in this review. Findings on EEG and advanced neuroimaging in the reflex seizures and epilepsies, treatment and preventive options, and animal models and mechanisms are also discussed.

Proof of principle studies

Proof of Principle studies are an early stage of clinical drug development when a compound has shown potential in animal models and early safety testing. This step of proof-of-principle (PoP) or proof-of-concept (PoC) often links between Phase-I and dose ranging Phase-II studies. These small-scale studies are designed to detect a signal that the drug is active on a pathophysiologically relevant mechanism, as well as preliminary evidence of efficacy in a clinically relevant endpoint. Sponsors use these studies to estimate whether their compound might have clinically significant efficacy in other diseases states as well as epilepsy (e.g., migraine, neuropathic pain, anxiety, depression). Endpoints other than seizure frequency often reveal special characteristics of the drug. A structured dose escalation design can reveal dose-dependent effects and adverse effects, crossover studies can demonstrate change, presurgical studies can define efficacy, interictal discharges and photosensitivity models can explain changes in seizure features, transcranial magnetic stimulation evaluates hyperexcitability. PoP studies allow exploration of a wide range of potential therapeutic areas beyond epilepsy as part of an integrated CNS development plan.

Refractory calculation-induced idiopathic generalized epilepsy: a case report and review of the literature

We report a case with calculation-induced idiopathic generalized epilepsy (IGE) that, unlike most patients with IGE, was refractory to medications. This patient had a family history of (1) a similar condition in a relative of hers who, however, did not have identical manifestations, and (2) a mother who had migraine. Our observations illustrate that the occurrence of IGE in families usually follows rather complex patterns of inheritance and that some of them can be refractory to therapy.

Photosensitivity in Idiopathic Generalized Epilepsies

Photosensitivity is an abnormal visual sensitivity of the brain in reaction to flickering light sources or patterns and is expressed in the electroencephalogram as generalized spike-and-wave discharge and in more susceptible individuals as clinical seizures. The most common types of seizures are generalized tonic-clonic, followed by myoclonic and absence. The photosensitive epilepsies are classified as pure photosensitive, where seizures occur only with the flickering light source/pattern or during intermittent photic stimulation (IPS) in the laboratory, and epilepsy with photosensitivity, where spontaneous seizures also occur. Positive response to IPS in idiopathic epilepsy syndromes, which are included in the International Classification or are in development, is reported to range from 7.5% in juvenile absence epilepsy to 100% in pure photosensitive epilepsy. The treatment of photosensitivity and pure photosensitive epilepsy with rare seizures includes general and specific protective measures. For most patients, however, combination treatment with antiepileptic drugs is necessary. Valproic acid monotherapy has a success rate of 73-86%. Levetiracetam appears to be a new alternative therapeutic option. Clobazam, lamotrigine, ethosuximide, and topiramate also have been recommended as second-choice therapies.

CPP and amlodipine alter the decrease in basal acetylcholine and choline release by audiogenic stimulus in hippocampus of ethanol-withdrawn rats in vivo

Effects of N-methyl-D-aspartate (NMDA) receptor and Ca2+ channel antagonists on extracellular acetylcholine and choline release in the hippocampus of ethanol-withdrawn rats were investigated by in vivo microdialysis. Ethanol was administered to Wistar rats in a liquid diet for 28 days. Basal acetylcholine and choline levels significantly increased at the 24th hour of ethanol withdrawal syndrome (EWS). Either an NMDA receptor antagonist (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or a calcium channel antagonist amlodipine was administered, and 15 min later, an audiogenic stimulus (100 dB, 1 min) was applied to rats. While audiogenic stimulus increased acetylcholine and had no effect on choline release in control rats, it decreased acetylcholine and increased choline release in ethanol-withdrawn rats. CPP (15 mg/kg) and amlodipine (20 mg/kg) reversed the decrement in acetylcholine and increment in choline release in EW rats. Their effects on acetylcholine and choline release were not different from saline in control rats. Therefore, our findings suggest that, (a) because of adaptive changes in EWS, decrease of the acetylcholine release following audiogenic stimulus may play a role in the triggering of seizures, (b) hippocampal glutamatergic pathway may play a role in the audiogenic stimulus induced decrement of acetylcholine release in EWS, (c) inhibition of this pathway by NMDA receptor and calcium channel antagonists may prevent triggering of the seizures.

Involvement of Scn1b and Kcna1 ion channels in audiogenic seizures and PTZ-induced epilepsy

We have undertaken chemical genetic approach using Qingyangshenylycosides (QYS), a natural product compound, to explore the molecular mechanisms underlying different types of epilepsy models. Two animal models were used for these studies, i.e., audiogenic seizure (AGS) and pentylenetetrazol (PTZ)-induced generalized epilepsy in DBA/2J mice. We show that the latency of AGS is prolonged and the severity of seizures (the percentages of the tonus, Tonus_%) is reduced in the QYS-treated animals. These results indicate that QYS has anticonvulsant effect on the AGS model. However, we find that administration of QYS has an opposite effects on PTZ-induced generalized epilepsy. Both the latency of the generalized epilepsy and the latency of death are decreased after QYS treatment in PTZ-induced epilepsy. We examine the molecular basis of the distinct roles of QYS in these two epilepsy models by using gene expression data. Our results show that a voltage-gated sodium channel (Scn1b) and a voltage-gated potassium channel (Kcna1) are differentially expressed in AGS and PTZ-induced epilepsy models as well as in QYS-treated animals. Our results demonstrate that a chemical genetic approach may help to reveal both the molecular mechanisms of different epilepsies and the mechanism of action of the antiepileptic drugs.

Gene expression profiling reveals the mechanism of action of anticonvulsant drug QYS

We have examined the gene expression profiling of inferior colliculus from DBA/2J mice with high-intensity noise induced audiogenic seizure (AGS). We have also tested the effects of Qingyangshenylycosides (QYS), a traditional Chinese medicine, on the audiogenic seizure, and examined how the drug affected the gene expressions in inferior colliculus. Our results demonstrated that the latency was increased and the Tonus% of AGS was decreased in the animals treated with QYS, indicating that the drug effectively prevented audiogenic seizure. Gene expression analysis using Agilent oligo microarray showed that total of 134 genes were either up- or down-regulated during AGS. QYS prevented many of the AGS induced gene expression changes. Nevertheless, some of the AGS induced genes were further enhanced or reversed by QYS treatment. Our gene expression profiling data provided important information regarding the molecular mechanisms of AGS and the mechanism of action of QYS. Further analysis of the function of these genes may help to identify therapeutic targets for epilepsy.

[The anticonvulsive effect of 4,4-bis(hydroxymethyl)-2-phenyl-2-oxazoline]

INTRODUCTION

Certain compounds belonging to the family of the 2-aryl oxazolines have been reported to act on the central nervous system with a number of different effects and applications, which make them useful as depressants, anaesthetics, anticonvulsants, and so on.

AIMS

Our aim was to study the possible effect of 4,4-bis(hydroxymethyl)-2-phenyl-2-oxazoline (OX), obtained by chemical synthesis using microwaves, in two experimental models of epilepsy.

MATERIALS AND METHODS

Two models were used: one involving (repeated stimulation) electroconvulsive shock in mice and the other consisted in inducing audiogenic seizures in Mongolian gerbils. Recordings were performed of the potentials in the dentate gyrus (DG) generated in response to electrical stimulation of the entorhinal cortex in anaesthetised gerbils, using the stereotactic technique.

RESULTS

A 150 mg/kg dose of OX lowered the number of electrical pulses required to induce the tonic seizures triggered by the electroshock, as well as their duration. This same dose blocked the seizures induced by audiogenic stimuli in the gerbils and significantly reduced their severity (degrees of seizures) and occurrence. OX diminished, in a dose-dependent manner, the amplitude of the excitatory post-synaptic potential and that of the population spike, triggered by stimulating the entorhinal cortex in the DG.

CONCLUSIONS

OX acts as an antiepileptic agent and its mechanism of action could be related to the inhibiting effect it exerts on the entorhinal cortex-DG synapses in the hippocampus.

Antiepileptic activity of delta sleep-inducing peptide and its analogue in metaphit-provoked seizures in rats

PROBLEM

Previous studies have shown that humoral, endogenous and somnogenic, delta sleep-inducing peptide (DSIP) has influence on insomnia, pain, adaptation to stress, epilepsy, etc. We investigated the potential of DSIP and its analogue DSIP-12 (a nonapeptide with alanine in position 2 of DSIP molecule substituted by beta-alanine) to antagonize metaphit (1-[1(3-isothiocyanatophenyl)-cyclohexyl]piperidine) induced generalized, reflex audiogenic seizures in adult male Wistar albino rats.

METHODS

The rats divided in four groups received (i.p.): saline; metaphit; metaphit+DSIP; and metaphit+DSIP-12, respectively. Metaphit-treated animals displaying seizure in eight previous tests received DSIP or DSIP-12 and afterwards audiogenic stimuli were applied at hourly intervals for the next 30 h. The animals were exposed to sound stimulation 60 min after metaphit administration and further on at hourly intervals. Incidence and severity of seizures were behaviorally analyzed. Selected EEGs and power spectra were recorded and analyzed.

RESULTS AND CONCLUSIONS

Metaphit led to hypersynchronous epileptiform activity (polyspikes and spike-wave complexes) and increased power spectra 0.5-30 h after the treatment. Severity of metaphit seizures increased with time to reach the peak 7-12 h after injection. DSIP and DSIP-12 significantly (*P<0.05 and **P<0.01) increased in delta and theta frequency bands and decreased the incidence, mean seizure grade and duration of metaphit convulsions. The results suggest that DSIP and DSIP-12 may be considered as potential antiepileptics in the animal model, DSIP-12 being more efficient than DSIP.

Visually Self-induced Seizures Sensitive to Round Objects

PURPOSE

To describe a previously unreported type of self-induced pattern-sensitive seizures in a child.

METHODS

Evaluation of clinical and EEG features.

RESULTS

An 18-month-old boy was initially seen with series of short focal tonic seizures self-induced by gazing intermittently at round objects. Self-induction of these seizures had an obvious relieving effect on the child. Covering the round object foiled further seizures but resulted in a tantrum. Later in the course, an increasing variety of patterns proved to be capable of inducing seizures, which occurred with increasing frequency and severity, including secondarily generalized tonic-clonic seizures. Interictal EEG revealed multifocal sharp-and-slow-waves. Ictal EEG showed no abnormalities during short focal seizures and rapidly generalizing epileptic discharges during a secondarily generalized seizure. No photosensitivity was noted. Motor and mental development of the boy stagnated over a period of 2 years. Behavioral therapy as well as medical treatment, consisting of various combinations of antiepileptic drugs (AEDs) together with a selective serotonin-reuptake inhibitor, were of merely transient benefit. Only combined pharmacotherapy, including valproate, sulthiame, and clobazam, resulted in seizure control at age 3 years 9 months.

CONCLUSIONS

Visual capture of geometric patterns other than stripes or gratings may trigger focal seizures with secondary generalization. Synchronization of cortical neurons responsible for pattern recognition may account for epileptogenesis in this child.

[Remote effects of early postnatal pituitary hormone melatonin injection on audiogenic seizures in Krushinsky-Molodkina rats]

Rats Krushinsky-Molodkina inbred strain (KM) genetically prone to audiogenic seizures were injected with pineal hormone melatonin (50 mg/kg, s.c.) within the period 7th to the 14th posnatal days (PND). The remote effects of this injection adult KM rats consisted in a decrease in the latency and increase in severity of myoclonic seizures produced by audiogenic kindling (20 sound stimuli, 100 dB and 12-15 kHz). As compared to the control, in the cortex and hippocampus of rats of melatonin group, we also found a significant reduction of both total and functional activity of Ca2+/calmodulin-dependent protein kinase II (CAMK II) after audiogenic kindling. On the contrary, melatonin administration within the 1st to 7th PND and the 14th to the 21st PND resulted in a decrease in seizure activity. In the first case, both the total (cortical) and functional (hippocampal) CAMK II activities in melatonin-injected rats were increased as compared to control, whereas in the second case, only a slight increase in Ca2+-independent CAMK II activity in the hippocampus of melatonin-injected rats was observed. Probably, the melatonin administration in the period of early postnatal development changes the features of expression and/or regulation of CAMK II activity, and this could be one of the mechanisms of audiogenic seizure modulation in KM rats.

Pattern-sensitive Epilepsy: Electroclinical Characteristics, Natural History, and Delineation of the Epileptic Syndrome

PURPOSE

To elucidate the electroclinical features and long-term outcome of patients with pattern-sensitive epilepsy.

METHODS

We reviewed the clinical and electroencephalographic (EEG) findings of 73 (43 female and 30 male) patients in whom pattern-sensitive epilepsy was diagnosed at Mayo Clinic (Rochester, Minnesota, U.S.A.) from 1950 through 1999. We contacted patients and their relatives by letter or telephone to obtain the latest seizure and quality-of-life outcomes.

RESULTS

The median age at onset of seizures was 12.8 years (range, 0.6-32.9 years). Most patients had absence, myoclonic, or generalized tonic-clonic seizures. Interictal epileptiform discharges in the EEG were detected in 61 (83.6%) patients and were generalized in 54 (74%). Paroxysmal epileptiform discharges in the EEG elicited with standard patterns were all generalized in two thirds of patients but were restricted to the posterior head region in one-third. Eight (11%) patients did not exhibit photosensitivity. Television was the most common precipitant [30 patients (41%)]. Twenty-nine patients gave a clear history of one or more seizures precipitated while viewing environmental patterns such as window screens, garments, tablecloths, and ceiling tiles; the rest of the patients admitted that they preferred to avoid looking at patterned objects because these objects made them uncomfortable. The electroclinical features suggested juvenile myoclonic epilepsy in 14 patients, progressive myoclonus epilepsy in three, progressive familial cerebellar ataxia with myoclonus in two, and severe myoclonic epilepsy of infancy in one. During a median follow-up period of 15.7 years, 25 (45.5%) of 55 patients who were followed up for > or =5 years achieved complete seizure remission. The median age at remission was 24.4 years. The absence of progressive neurologic disease was correlated significantly with remission; a family history of seizures showed a trend in favor of remission. More than two thirds of the patients did not consider the seizures an impediment to their family life or to educational and occupational achievements.

CONCLUSIONS

Although pattern sensitivity as a trait occurs in various epileptic syndromes, pattern-sensitive epilepsy is a readily distinguishable subtype of the visually provoked reflex epilepsies. In our opinion, the location and extent of the excitable region or regions within the visual cortex concerned with different attributes of visual function dictate susceptibility to a specific trigger (intermittent light, pattern, or color) or closely related multiple triggers and the resultant electroclinical phenomenon.

Mah-Jong-induced epilepsy: a special reflex epilepsy in Chinese society

We present five patients of epilepsy in which seizures were triggered by playing or watching the traditional Chinese gambling game "Mah-Jong." One patient also experienced seizures while playing a computer version of the Mah-Jong game. This condition appeared to have a predominance of males (80%) and middle-aged onset (39.4 years). Four patients had generalized tonic-clonic seizures and one patient had partial seizures with secondary generalization. No spontaneous seizure occurred in these patients. Three patients had been receiving antiepileptic drug therapy, but without effective control over their seizures. Mah-Jong-induced epilepsy is a very peculiar form of complex reflex epilepsy that involves the higher mental activities. This phenomenon may consist of distinct pathophysiologic mechanisms from other reflex epilepsy induced by thinking and spatial tasks in idiopathic generalized epilepsies. This unusual reflex epilepsy is relatively benign in nature and antiepileptic drug therapy has uncertain benefits. It may be necessary to avoid playing the Mah-Jong game in order to prevent seizures.