Status epilepticus-induced neuronal loss in humans without systemic complications or epilepsy

Prophylactic treatment with levetiracetam after status epilepticus: lack of effect on epileptogenesis, neuronal damage, and behavioral alterations in rats

Levetiracetam (LEV) is a structurally novel antiepileptic drug (AED) which has demonstrated a broad spectrum of anticonvulsant activities both in experimental and clinical studies. Previous experiments in the kindling model suggested that LEV, in addition to its seizure-suppressing activity, may possess antiepileptogenic or disease-modifying activity. In the present study, we evaluated this possibility by using a rat model in which epilepsy with spontaneous recurrent seizures (SRS), behavioral alterations, and hippocampal damages develop after a status epilepticus (SE) induced by sustained electrical stimulation of the basal amygdala. Two experimental protocols were used. In the first protocol, LEV treatment was started 24h after onset of electrical amygdala stimulation without prior termination of the SE. In the second protocol, the SE was interrupted after 4h by diazepam, immediately followed by onset of treatment with LEV. Treatment with LEV was continued for 8 weeks (experiment #1) or 5 weeks (experiment #2) after SE, using continuous drug administration via osmotic minipumps. The occurrence of SRS was recorded during and after treatment. In addition, the rats were tested in a battery of behavioral tests, including the elevated-plus maze and the Morris water maze. Finally, the brains of the animals were analyzed for histological lesions in the hippocampal formation. With the experimental protocols chosen for these experiments, LEV did not exert antiepileptogenic or neuroprotective activity. Furthermore, the behavioral alterations, e.g., behavioral hyperexcitability and learning deficits, in epileptic rats were not affected by treatment with LEV after SE. These data do not support the idea that administration of LEV after SE prevents or reduces the long-term alterations developing after such brain insult in rats.

Childhood status epilepticus and excitotoxic neuronal injury

This report describes the case of an 11-year-old girl with a prior history of epilepsy and multiple episodes of status epilepticus who presented with generalized convulsive status epilepticus and left hemiclonic seizures. Magnetic resonance imaging, including diffusion-weighted sequences and spectroscopy, and neuropathology at autopsy were consistent with excitotoxic neuronal injury to the hippocampus, cortex, thalamus, mammillary bodies, and cerebellum. Review of the literature revealed 11 similar cases that support the hypothesis of excitotoxic neuronal cell death after status epilepticus.

Effects of topiramate on methamphetamine-induced changes in attentional and perceptual-motor skills of cognition in recently abstinent methamphetamine-dependent individuals

Methamphetamine-dependent individuals often cite the need to maintain enhanced cognitive performance and attention as a reason for continuing or relapsing to drug-taking. Further, methamphetamine addicts might not comply with taking a potentially therapeutic medication if it had a profound effect on these cognitive processes. Topiramate, a sulfamate-substituted fructopyranose derivative, has been suggested as a putative therapeutic medication for treating methamphetamine dependence. Examination of topiramate's effects on cognitive performance and attention is a clinically and scientifically important component of understanding its potential therapeutic profile. In 10 male and female individuals who met DSM-IV criteria for methamphetamine dependence, we examined the effects of low (50 mg b.i.d.)- and high (100 mg b.i.d.)-dose topiramate - in both the presence and absence of low (15 mg)- and high (30 mg)-dose intravenous methamphetamine--on cognitive performance, attention, and concentration on the rapid visual information processing task and the digit symbol substitution test. Intravenous methamphetamine enhanced cognitive performance, attention, and concentration among recently withdrawn methamphetamine addicts--an effect that hitherto had not been well characterized. Topiramate's cognitive effects were mixed and rather paradoxical, with a tendency to improve attention and concentration both alone and in the presence of methamphetamine while worsening psychomotor retardation. No deleterious interaction occurred between topiramate and methamphetamine on any of these cognitive processes. While clinical studies with topiramate should prepare participants for possible psychomotor retardation, the cognitive effects profile observed would not likely present an important obstacle to compliance in motivated patients. Topiramate's complicated cognitive effects among methamphetamine addicts need more comprehensive examination.

Influence of persistent contaminants and steroid hormones on glioblastoma cell growth

Glioblastoma multiforme (GBM), a malignancy characterized by its rapid progression, presents a lower risk of occurrence in women during their reproductive years. Necrosis of brain tissue during tumor invasion releases free lipids, and therefore might release contaminants stored in phospholipid-rich neuronal tissue. This study assesses the growth response of two human glioblastoma cell lines, T98G and U138-MG, treated with environmental chemicals known or likely to persist within the brain. Persistent chlorinated pesticides, industrial contaminants, persistent perfluorinated chemicals, and steroid hormones were assayed over a range of concentrations. Although cytotoxic effects were seen in both T98G and U138-MG cells, proliferative responses occurred only in the T98G cell line. Dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyl (PCB) 153 were cytotoxic in both lines at 5000 nM. Perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and testosterone stimulated proliferation in the T98G cells at 500, 1000, and 1000 nM, respectively. However, a perfluorinated salt (ammonium perfluorooctanoate; C8) and a weak androgen (dihydroepiandrosterone; DHEA) did not affect relative cell number in this GBM line, suggesting the proliferative effect is not through the activation of an androgen receptor. Exposure to environmental chemicals that result in a mitogenic response may increase the rate of glioblastoma tumor growth and result in the development of more aggressive forms of GBM tumors.

Preferential neuron loss in the rat piriform cortex following pilocarpine-induced status epilepticus

Structures within the piriform cortex (PC) including the endopiriform nucleus (DEN) and pre-endopiriform nucleus (pEn) have been implicated to be involved in seizure genesis in models of temporal lobe epilepsy. We used stereological methods to examine the specificity and extent of neuron loss in the PC of pilocarpine-treated rats. Both 7 days and 2 months post-status epilepticus rats showed significant neuron loss in the pEn and DEN, layer III of the intermediate PC, and layers II and III of the caudal PC. Total losses in the PC were 40 and 46% in 7 days and 2 months post-status epilepticus rats, respectively (p<0.01). The numbers of parvalbumin (PV)- and cholecystokinin (CCK)-immunopositive neuron profiles significantly decreased, and somatostatin (SS)-immunopositive neuron profiles tended to decrease. A large decrease in the number of PV-immunopositive neuron profiles occurred in the pEn, adjoining parts of the DEN and deep layer III of the PC, portions of the DEN bordering the claustrum and agranular insular cortex, and layer III of the caudal PC. The regions with decreased numbers of PV-, CCK-, and SS-immunopositive neuron profiles overlapped with those where many Nissl-stained neurons were lost and many degenerating cell bodies were detected. These results suggest that the decreases in the numbers of PV/SS/CCK-immunopositive neurons are related to neuron loss rather than to a low rate of synthesis of their peptides or proteins.

Antiepileptic drug-resistant rats differ from drug-responsive rats in hippocampal neurodegeneration and GABA(A) receptor ligand binding in a model of temporal lobe epilepsy

The disabling seizures associated with mesial temporal lobe epilepsy (TLE) are often resistant to antiepileptic drugs (AEDs). The biological basis of this refractoriness is unknown but may include alterations in AED targets in the epileptogenic brain tissue, reduced AED penetration to the seizure focus, and neuropathological brain alterations such as hippocampal sclerosis typically found in patients with refractory TLE. In the present study, we used a rat model of TLE to examine whether AED responders differ from non-responders in their structural alterations and GABA(A) receptor characteristics in the hippocampal formation. In this model, spontaneous recurrent seizures develop after a status epilepticus induced by prolonged electrical stimulation of the basolateral amygdala. The frequency of these seizures was recorded by continuous video/EEG monitoring before, during, and after daily treatment with phenobarbital, which was given at maximum tolerated doses for 2 weeks. Based on their individual response to phenobarbital, rats were grouped into responders and non-responders. The severity or duration of the initial brain insult (the status epilepticus) did not differ between responders and non-responders, indicating that the difference between the two subgroups is genetically determined. Subsequent histological examination showed a significant loss of neurons in the CA1, CA3c/CA4, and dentate hilus of non-responders, whereas responders did not differ in this respect from non-epileptic controls. The morphological alterations in the non-responders were associated with striking alterations in autoradiographic imaging of diazepam-sensitive and diazepam-insensitive GABA(A) receptor binding in the dentate gyrus with a significant shift to enhanced diazepam-insensitive binding. The present data indicate that neurodegeneration and associated GABA(A) receptor changes in the dentate gyrus are critically involved in the mechanisms underlying refractoriness of seizures in TLE.

Stereological analysis of forebrain regions in kainate-treated epileptic rats

Patients and models of temporal lobe epilepsy display neuron loss in the hippocampal formation, but neuropathological changes also occur in other forebrain regions. We sought to evaluate the specificity and extent of volume loss of the major forebrain regions in epileptic rats months after kainate-induced status epilepticus. In systematic series of Nissl-stained sections, the areas of major forebrain regions were measured, and volumes were estimated using the Cavalieri principle. In some regions, the optical fractionator method was used to estimate neuron numbers. Most kainate-treated rats showed significant volume loss in the amygdala, olfactory cortex, and septal region, but others displayed different patterns, with significant loss only in the hippocampus or thalamus, for example. Average volume loss was most severe in the amygdala and olfactory cortex (82-83% of controls), especially the caudal parts of both regions. In the piriform cortex (including the endopiriform nucleus) of epileptic rats, an average of approximately one-third of Nissl-stained neurons and one-third of the GABAergic interneurons labeled by in situ hybridization for GAD67 mRNA were lost, and the extent of neuron loss was correlated with the extent of volume loss. Volumetric analysis of major forebrain regions was insensitive to specific neuron loss in subregions such as layer III of the entorhinal cortex and the hilus of the dentate gyrus. These findings provide quantitative evidence that kainate-treated rats tend to display extensive neuron and volume loss in the amygdala and olfactory cortex, although the patterns and extent of loss in forebrain regions vary considerably among individuals. In this status epilepticus-based model, extrahippocampal damage appears to be more extensive and hippocampal damage appears to be less extensive than that reported for patients with temporal lobe epilepsy.

Intellectual Prognosis of Status Epilepticus in Adult Epilepsy Patients: Analysis with Wechsler Adult Intelligence Scale-Revised

PURPOSE

Status epilepticus (SE) appears to cause cognitive dysfunction as well as other serious neurologic sequelae. To confirm whether SE produces a subsequent intellectual decline, we evaluated intellectual function prospectively in adult epilepsy patients with and without SE.

METHODS

Of 1,685 patients with epilepsy who underwent comprehensive neuropsychological testing in two national hospitals in Japan, 15 patients experienced an episode of SE afterward and underwent the second neuropsychological examination after the SE episode. Forty clinically matched patients with epilepsy, but without an episode of SE since their initial neuropsychological examination, were also reevaluated. We compared IQs and subscores from the Wechsler Adult Intelligence Scale-Revised between the two groups by repeated measures analysis of variance. In the patients who experienced an SE episode, SE-related variables (i.e., age at the SE episode and type and duration of SE) and epilepsy-related variables such as epilepsy type, lateralization of EEG abnormalities, the presence of mesial temporal sclerosis, and previous history of SE, were evaluated in relation to intellectual outcome.

RESULTS

Patients with SE, in comparison to those without SE, failed to show any significant post-SE intellectual decline. Furthermore, neither the SE-related variables nor the clinical characteristics were correlated with intellectual outcome.

CONCLUSIONS

Our findings suggest that SE does not lead to a significant intellectual decline in adult patients receiving treatment for epilepsy.

Advances in the pathophysiology of developmental epilepsies

Pediatric epilepsies display unique characteristics that differ significantly from epilepsy in adults. The immature brain exhibits a decreased seizure threshold and an age-specific response to seizure-induced brain injury. Many idiopathic epilepsy syndromes and symptomatic epilepsies commonly present during childhood. This review highlights recent advances in the pathophysiology of developmental epilepsies. Cortical development involves maturational regulation of multiple cellular and molecular processes, such as neurogenesis, neuronal migration, synaptogenesis, and expression of neurotransmitter receptors and ion channels. These normal developmental changes of the immature brain also contribute to the increased risk for seizures and unique responses to seizure-induced brain injury in pediatric epilepsies. Recent technological advances, especially in genetics and imaging, have yielded exciting discoveries about the pathophysiology of specific pediatric epilepsy syndromes, such as the emergence of channelopathies as the cause of many idiopathic epilepsies and identification of malformations of cortical development as a major source of symptomatic epilepsies in children.

Epilepsy induced by extended amygdala-kindling in rats: lack of clear association between development of spontaneous seizures and neuronal damage

Most patients with temporal lobe epilepsy (TLE), the most common type of epilepsy, show pronounced loss of neurons in limbic brain regions, including the hippocampus, amygdala, and parahippocampal regions. Hippocampal damage in patients with TLE is characterized by extensive neuronal loss in the CA3 and CA1 sectors and the hilus of the dentate gyrus. There is a long and ongoing debate on whether this type of hippocampal damage, referred to as hippocampal sclerosis, is the cause or consequence of TLE. Furthermore, hippocampal damage may contribute to the progressive features of TLE. The present study was designed to determine whether development of spontaneous recurrent seizures (SRS) after extended kindling of the amygdala in rats is associated with neuronal damage. The kindling model of TLE was chosen because previous studies have shown that only part of the rats develop SRS after extended kindling, thus allowing to compare the brain pathology of rats that received the same number of amygdala stimulation but did or did not develop SRS. For extended kindling, rats were stimulated twice daily 3-5 days a week for up to about 280 stimulations. During long-term EEG/video monitoring, SRS were observed in 50% of the rats over the period of extended kindling. SRS often started with myoclonic jerks or focal seizures and subsequently progressed into secondarily generalized seizures, so that the development of SRS recapitulated the earlier kindling of elicited seizures. No obvious neurodegeneration was observed in the CA1 and CA3 sectors of the hippocampus, the amygdala, parahippocampal regions or thalamus. A significant bilateral reduction in neuronal density was determined in the dentate hilus after extended kindling, but this reduction in hilar cell density did not significantly differ between rats with and without observed SRS. Determination of the total number of hilar neurons and of hilar volume indicated that the reduced neuronal density in the dentate hilus was due to expansion of hilar area but not to neuronal damage. The data demonstrate that extended kindling does not cause any hippocampal damage resembling hippocampal sclerosis, but that SRS develop in the absence of such damage.

Susceptibility of immature and adult brains to seizure effects

The extent that status epilepticus (SE), but also brief seizures, affects neuronal structure and function has been the subject of much clinical and experimental research. There is a reliance on findings from animal research because there have been few prospective clinical studies. This review suggests that the features of seizure-induced injury in the immature brain compared with the adult brain are different and that duration of seizures (SE versus brief), number of seizures, cause of seizures, presence of pre-existing abnormalities, and genetics affect the injury. Increased awareness of age-specific injuries from seizure has promoted research to determine the circumstances under which seizures may produce permanent detrimental effects. Together with recent advances in functional neuroimaging, genomic investigation, and prospective human data, these studies are likely to substantially increase our knowledge of seizure-induced injury, leading to the development of improved algorithms for prevention and treatment of epilepsy.

Electroencephalographic, behavioral, and c-fos responses to acute domoic acid exposure

Domoic acid, a potent excitotoxic analogue of glutamate and kainate, may cause seizures, amnesia, and sometimes death in humans consuming contaminated shellfish. Continuous behavioral observations and recordings of the electrocorticogram (ECoG, via bipolar, epidural electrodes) were obtained from nonanesthetized rats for 2 h after intraperitoneal injection with either saline, 2.2, or 4.4 mg/kg of domoic acid. Rats were then sacrificed for c-fos immunohistochemistry. Fast Fourier transformation (FFT) of the ECoG data to obtain the voltage as a function of frequency indicated that the lower frequency bands (theta, 4.75-6.75 Hz and delta, 1.25-4.50 Hz) were the first to respond, with a significant elevation by 30 min after the high dose of domoic acid. The lower dose of domoic acid also caused a significant elevation of ECoG voltage, but not until later in the session. Sixty minutes after dosing, the behavioral biomarkers of "ear scratching" and "rearing, praying" (RP) seizures became significantly elevated in the high-dose rats. The low-dose rats showed no significant alterations in behavior at any time during the session. In postmortem brains obtained immediately after the sessions, c-fos was activated in the anterior olfactory nucleus by both the low and high doses of domoic acid. However, only the high dose increased c-fos immunoreactivity in the hippocampus, affecting both the granule and pyramidal neurons. These data indicate that electroencephalographic and c-fos responses can be obtained at a dose of domoic acid that fails to activate the behavioral response most commonly used as a bioassay for this marine toxin: ear scratching with the ipsilateral foot.

Patterned Purkinje cell death in the cerebellum

The object of this review is to assemble much of the literature concerning Purkinje cell death in cerebellar pathology and to relate this to what is now known about the complex topography of the cerebellar cortex. A brief introduction to Purkinje cells, and their regionalization is provided, and then the data on Purkinje cell death in mouse models and, where appropriate, their human counterparts, have been arranged according to several broad categories--naturally-occurring and targeted mutations leading to Purkinje cell death, Purkinje cell death due to toxins, Purkinje cell death in ischemia, Purkinje cell death in infection and in inherited disorders, etc. The data reveal that cerebellar Purkinje cell death is much more topographically complex than is usually appreciated.

Excessive weight gain in rats over extended kindling of the basolateral amygdala

Previous lesion studies have indicated a role of the amygdala in the central regulation of food intake. In the present experiments, twice-daily electrical stimulation of the basolateral nucleus of the amygdala in female Wistar rats was found to be associated with a significant body weight gain compared to unstimulated controls. On average, significant increases in body weight were observed after 25 amygdala stimulations, using a kindling paradigm for stimulation. Compared to kindled rats, in which amygdala stimulations were terminated after about 20 stimulations, extended kindling of the amygdala with up to 280 stimulations led to progressive weight increases and compulsive hyperphagia. No gross neuronal damage was seen in thionin-stained sections of the amygdala after extended kindling, but degeneration of a specific type of neurons can not be excluded. The results substantiate that amygdaloid nuclei are an important extrahypothalamic site for the regulation of food intake and body weight. The extensive weight gain over extended amygdala kindling provides an interesting new model for experimentally induced obesity.

N-methyl-D-aspartate receptor blockade after status epilepticus protects against limbic brain damage but not against epilepsy in the kainate model of temporal lobe epilepsy

Most patients with temporal lobe epilepsy (TLE), the most common type of epilepsy, show pronounced loss of neurons in limbic brain regions, including the hippocampus. The massive neurodegeneration in the hippocampus is known as hippocampal sclerosis, and is considered one of the hallmarks of this type of difficult-to-treat epilepsy. There is a long and ongoing debate on whether this sclerosis is the result of an initial pathological event, such as a status epilepticus (S.E.), stroke or head trauma, which often precedes the development of TLE, or is caused by the spontaneous recurrent seizures (SRS) once epilepsy has developed. At present, pharmacological prevention of limbic sclerosis is not available. In a clinical situation, such prevention would only be possible if delayed cell death developing after an initial pathological event is involved. Assuming that sclerotic brain lesions provoke epileptogenesis and that delayed cell death is involved in these lesions, it should be possible to prevent both the lesions and the epilepsy by a prophylactic treatment after an initial insult such as an S.E. In order to test this hypothesis, we used a rat model of TLE in which limbic brain lesions and epilepsy with SRS develop after a kainate-induced S.E. A single low dose of the N-methyl-D-aspartate (NMDA) receptor blocker dizocilpine (MK-801) significantly reduced the damage in limbic regions, including the hippocampus and piriform cortex, and completely protected several rats from such damage when given after an S.E. of 90 min induced by kainate, strongly suggesting that delayed cell death is involved in the damage. This was substantiated by the use of molecular and immunohistochemical markers of delayed active ("programmed") cell death. However, the neuroprotection by dizocilpine did not prevent the development of SRS after the S.E., suggesting that structures not protected by dizocilpine may play a role in the genesis of SRS or that epileptogenesis is not the consequence of structural lesions in the limbic system. The only brain regions that exhibited neuronal damage in all rats with SRS were the hilus of the dentate gyrus and the mediodorsal thalamus, although treatment with dizocilpine reduced the severity of damage in the latter region. The data indicate that NMDA receptor blockade immediately after a prolonged S.E. is an effective means to reduce the damage produced by a sustained S.E. in several brain regions, including the hippocampus, but show that this partial neuroprotection of the limbic system does not prevent the development of epilepsy.

Epileptogenesis and neuropathology after different types of status epilepticus induced by prolonged electrical stimulation of the basolateral amygdala in rats

It has previously been shown that prolonged (60-min) low-intensity electrical stimulation of a kindled focus in the basolateral nucleus of the amygdala (BLA) of Wistar rats resulted in the development of self-sustained status epilepticus (SSSE) with predominantly partial seizures and subsequent brain damage in the ipsilateral hemisphere. In the present study, using high-intensity (700 microA) pulsed-train electrical stimulation of the BLA for 25 min, SSSE was induced in both kindled and non-kindled Wistar rats, demonstrating that under these experimental conditions prior kindling is not necessary to induce SSSE. Thus, all subsequent experiments were done in non-kindled rats of different strains (Wistar, Sprague-Dawley) and genders. Three distinct behavioral types of SSSE were observed: (1) continuous partial seizures; (2) continuous partial seizures, repeatedly interrupted by generalized convulsive seizures; and (3) continuous generalized convulsive seizures. These three forms of SSSE were seen in both strains and genders, although the percentage of rats in each strain and gender developing a specific type of SSSE differed. Rats spontaneously recovered from SSSE after between 3 and 8h on average, the SSSE duration depending on SSSE type, rat strain and gender. Following SSSE, rats were monitored with a video- and EEG-recording system for occurrence of spontaneous recurrent seizures (SRS). Overall, about 80% of the rats developed epilepsy with SRS after SSSE, but the proportion of rats developing SRS depended on the type of SSSE. Only 33% of the rats developed SRS after a partial SSSE, compared to >90% in case of either type 2 or type 3 SSSE with generalized convulsive seizures. Interruption of different forms of SSSE with diazepam after 90 min prevented development of epilepsy, while a generalized SSSE duration of 4h consistently produced epilepsy in >90% of rats. Histologic analysis of rat brains after the different SSSE types indicated that neuronal loss after partial SSSE was much more regionally restricted and less severe compared to neuronal damage after SSSE with generalized convulsive seizures, which was similar to the brain damage seen in the kainate and pilocarpine models of temporal lobe epilepsy. These experiments establish that prolonged electrical stimulation of the BLA induces different forms of SSSE that resemble nonconvulsive and convulsive types of SE in humans. These different forms of SSSE induce epilepsy with SRS and brain pathology reminiscent of temporal lobe epilepsy with hippocampal sclerosis. The rat model provides a new tool to mimic different types of SE and investigate the pathogenesis underlying their long-term complications.

Epileptic seizure prediction and control

Epileptic seizures are manifestations of epilepsy, a serious brain dynamical disorder second only to strokes. Of the world's approximately 50 million people with epilepsy, fully 1/3 have seizures that are not controlled by anti-convulsant medication. The field of seizure prediction, in which engineering technologies are used to decode brain signals and search for precursors of impending epileptic seizures, holds great promise to elucidate the dynamical mechanisms underlying the disorder, as well as to enable implantable devices to intervene in time to treat epilepsy. There is currently an explosion of interest in this field in academic centers and medical industry with clinical trials underway to test potential prediction and intervention methodology and devices for Food and Drug Administration (FDA) approval. This invited paper presents an overview of the application of signal processing methodologies based upon the theory of nonlinear dynamics to the problem of seizure prediction. Broader application of these developments to a variety of systems requiring monitoring, forecasting and control is a natural outgrowth of this field.

Sudden and unexpected death in epilepsy (SUDEP): evidence of acute neuronal injury using HSP-70 and c-Jun immunohistochemistry

Post-mortem and neuropathological examination in sudden and unexpected death in epilepsy (SUDEP) shows no specific lesions and the exact cause and mechanism of death in these cases remains undetermined. There is clinical evidence to support the fact that SUDEP is a seizure-mediated event, and patients with poorly controlled seizures are at higher risk. We aimed to identify any evidence of acute neuronal injury in SUDEP cases at post-mortem to support that a recent seizure had occurred. We analysed the distribution and frequency of heat shock protein (HSP)-70 and c-Jun immunopositive neurones in the hippocampus in 18 SUDEP cases and 22 control cases, both markers being nonspecific but early and reliable indicators of acute neuronal injury. Post-mortem control groups included patients with epilepsy with cause of death other than SUDEP (including status epilepticus and accidental death), and patients with sudden cardiac death without an epilepsy history. An additional surgical control group included patients with refractory epilepsy and hippocampal sclerosis who had undergone temporal lobectomy. Semiquantitative analysis of the distribution of HSP-70 staining showed significantly more SUDEP cases with positively labelled neurones in hippocampal subfields compared to epilepsy and cardiac post-mortem controls (P < 0.001) but not compared to the epilepsy surgical controls (P = 0.4). No significant difference in immunostaining patterns between groups was seen in the parahippocampal gyrus with HSP-70 or with c-Jun in either the hippocampus or parahippocampal gyrus regions. The detection of HSP-70 positive neurones in the hippocampus in SUDEP is supportive of ante-mortem neuronal injury including a recent seizure prior to death.

Prehospital Treatment of Status Epilepticus with Benzodiazepines Is Effective and Safe

Benzodiazepines are an effective and safe treatment of status epilepticus and serial seizures when used in an out-of-hospital setting. Intravenously administered lorazepam is somewhat superior to diazepam for the treatment of status epilepticus. Treatment of status epilepticus should be initiated when seizures have lasted 5-7 minutes.

Prehospital Treatment of Status Epilepticus with Benzodiazepines is Effective and Safe

Benzodiazepines are an effective and safe treatment of status epilepticus and serial seizures when used in an out-of-hospital setting. Intravenously administered lorazepam is somewhat superior to diazepam for the treatment of status epilepticus. Treatment of status epilepticus should be initiated when seizures have lasted 5–7 minutes.

Unilateral striatal damage following status epilepticus of ipsilateral frontal lobe origin

A 35-year-old man with an old contusional haematoma in the right frontal lobe developed status epilepticus (SE) of right frontal origin. On magnetic resonance (MR) images 10 days after SE, the right striatum showed signal enhancement with Gd-DTPA administration. Subsequent MR imaging 1 month later indicated prolonged T1 and T2 relaxation times in the right striatum. Prolonged seizure activity in the frontal lobe may have induced excitatory neurotoxicity in the ipsilateral striatum, with occurrence of delayed neuronal damage as a result.

Diagnosis and treatment of nonconvulsive status epilepticus

Nonconvulsive status epilepticus (SE) is not uncommon and comprises at least one-third of all cases of SE. However, nonconvulsive SE consists of very different syndromes, a common feature being the difficulty in making the diagnosis. In this review, nonconvulsive SE is divided into typical absence SE, complex partial SE, nonconvulsive SE in patients with learning difficulties (including electrical SE during sleep, atypical absence SE and tonic SE), and nonconvulsive SE in coma. These conditions have different prognoses and treatments. The diagnosis of these conditions is critically dependent on EEG. When the EEG demonstrates typical ictal patterns, the diagnosis is usually straightforward. However, in many circumstances the EEG has to be differentiated from encephalopathic patterns, and this differentiation can prove troublesome, although the clinical and electrographic response to treatment can prove helpful. Nonconvulsive SE in patients with learning difficulties possibly provides the greatest diagnostic difficulty; the clinical presentation can be subtle resulting in the diagnosis being frequently missed. Whether the neuronal damage that occurs in convulsive SE and in animal models of limbic SE also occurs in nonconvulsive SE in humans is still a matter of debate. There are critical differences between the animal models and the human condition. Indeed, the prognosis of nonconvulsive SE is usually dependent on the underlying aetiology rather than the persistence of electrographic discharges. Because of these doubts, a more conservative approach to the treatment of particular types of nonconvulsive SE (those with a better prognosis) has been taken in this article. Thus, in most instances, oral benzodiazepines for the treatment of typical absence SE and complex partial SE are recommended. In some circumstances intravenous medication is necessary, but in neither condition is anaesthetic coma recommended. This contrasts with nonconvulsive SE in coma in which a more aggressive approach is suggested. Until there are more relevant animal models, and controlled trials of conservative versus more aggressive treatment, treatment regimens for nonconvulsive SE will remain largely speculative.

Formation of the Apaf-1/cytochrome c complex precedes activation of caspase-9 during seizure-induced neuronal death

In this study we examine the in vivo formation of the Apaf-1/cytochrome c complex and activation of caspase-9 following limbic seizures in the rat. Seizures were elicited by unilateral intraamygdala microinjection of kainic acid to induce death of CA3 neurons within the hippocampus of the rat. Apaf-1 was found to interact with cytochrome c within the injured hippocampus 0-24 h following seizures by co-immunoprecipitation analysis and immunohistochemistry demonstrated Apaf-1/cytochrome c co-localization. Cleavage of caspase-9 was detected approximately 4 h following seizure cessation within ipsilateral hippocampus and was accompanied by increased cleavage of the substrate Leu-Glu-His-Asp-p-nitroanilide (LEHDpNA) and subsequent strong caspase-9 immunoreactivity within neurons exhibiting DNA fragmentation. Finally, intracerebral infusion of z-LEHD-fluoromethyl ketone increased numbers of surviving CA3 neurons. These data suggest seizures induce formation of the Apaf-1/cytochrome c complex prior to caspase-9 activation and caspase-9 may be a potential therapeutic target in the treatment of brain injury associated with seizures.

Sevoflurane mask induction of anaesthesia is associated with epileptiform EEG in children

BACKGROUND

Sevoflurane inhalation induction of anaesthesia is widely used in paediatric anaesthesia. We have found that this method is frequently associated with epileptiform electroencephalogram (EEG) in adults, especially if controlled hyperventilation is used.

METHODS

We assessed EEG during sevoflurane inhalation induction in 31 children, aged 2-12 yr. Anaesthesia was induced with 8% sevoflurane in O2 in N2O 1:2. The patients were randomized to undergo controlled ventilation (CV group), or to breathe spontaneously (SB group) for 5 min. EEG was recorded as were noninvasive blood pressure and heart rate (HR). EEG recordings were classified by a clinical neurophysiologist.

RESULTS

Three different types of interictal epileptiform discharge were detected. Suppression with spikes (SSP) was found in 25% and 0% in the CV and SB groups, rhythmic polyspikes (PSR) in 44% and 20%, and periodic epileptiform discharges (PED) in 44% and 0% (P<0.01), respectively. The incidence of all different types of interictal epileptiform discharge (SSP+PSR+PED) was 88% and 20% (P<0.001), respectively. Epileptiform EEG was associated with increased heart rate and blood pressure during anaesthetic induction.

CONCLUSION

Both ventilation modes produced epileptiform EEG. With controlled ventilation, epileptiform discharges were seen in 88% of children. This warrants further studies of the suitability of this induction type in general, and especially in children with epilepsy.

The etiology and diagnosis of status epilepticus

Status epilepticus (SE) is a common, serious, potentially life-threatening, neurologic emergency characterized by prolonged seizure activity. Generalized convulsive status epilepticus (GCSE) is the most widely recognized form of SE. Direct consequences of convulsive movements from SE can result in injury to the body and brain. Nonconvulsive status epilepticus (NCSE) is underrecognized, with controversy surrounding the consequences and treatment. High mortality rates with GCSE have been noted in the past. New treatments for SE are emerging with new parenteral drug formulations as well as new agents for refractory SE, offering an opportunity to improve outcome. Special drug delivery systems, drug combinations, and neuroprotective agents that prevent the subsequent development of epilepsy may soon emerge as future options for treating SE.

Therapy of status epilepticus in adults and children

Clinical studies of the treatment of status epilepticus are extremely difficult to carry out, therefore a paucity of new clinical studies have been reported. Much of the progress regarding the therapy of status epilepticus has come from a better understanding of the epidemiology of status epilepticus and its consequences and from laboratory studies of experimental status. Status epilepticus has been used as an experimental tool to study epileptogenesis, but from such studies have come insights that can be applied to the therapy of status epilepticus itself. This review will focus on information from epidemiological, experimental, and clinical studies of status epilepticus, which may contribute to the improved treatment of this life-threatening disorder.