Short Seizures Research Articles

The importance of acknowledging clinical uncertainty in the diagnosis of epilepsy and non-epileptic events

Background: Failure to recognise diagnostic uncertainty between the epilepsies and non-epileptic events may be a factor in high rates of misdiagnosis. Aims: To explore the results of acknowledging diagnostic uncertainty...

263 A Regularity-Based Seizure Detection Algorithm for Neonates

Background: Continuous EEG recordings in neonates are valuable both for monitoring of seizures and to measure response to therapy. Impediments to robust seizure detection include large datasets, limited availability of expert neurologist interpretation, the presence of low amplitude seizures and short seizures. Methods used to date in automatic seizure detection include Harmonie with Sensa software (Stellate Inc., Canada) based on Gotman et al (1997) algorithm.Objective: We evaluate a new approach to automated seizure detection (BrainZ Instruments Ltd., New Zealand) based predominantly on the assessment of relatively prolonged regularity in EEG waves.Design/Methods: The algorithm consists of the decomposition of EEG into adjacent waves and analysis of their regularity. Interval, amplitude and shape information were used in this regularity analysis. Conservative and liberal assessments (similar to integral-overlap and any-overlap, Wilson et al, 2003) of algorithm sensitivity and positive predictive value (PPV) were based on detected seizure duration. The algorithm performance was assessed on 52 multi channel EEG recordings of neonates totalling 20 hours, selected for the purpose of challenging the algorithm. The dataset included 14 EEG recordings with 81 seizures, 22 EEG recordings of normal patients with artefacts and 16 recordings of abnormal EEG.Results: For the BrainZ algorithm the conservative and liberal assessment of performance showed sensitivity of 83 and 95% and PPV of 52 and 75%, respectively. There were 1.8 false positive detections per hour. In comparison, the Sensa software (version 5.4) had sensitivity 37 and 85% and PPV 45 and 48%, respectively; with 11.7 false positives per hour.Conclusions: The regularity-based algorithm performed well and provides a basis for major improvements in neonatal seizure detection.

Cerebral Oxygenation during Postasphyxial Seizures in Near-Term Fetal Sheep

After exposure to asphyxia, infants may develop both prolonged, clinically evident seizures and shorter, clinically silent seizures; however, their effect on cerebral tissue oxygenation is unclear. We therefore examined the hypothesis that the increase in oxygen delivery during postasphyxial seizures might be insufficient to meet the needs of increased metabolism, thus causing a fall in tissue oxygenation, in unanesthetized near-term fetal sheep in utero (gestational age 125+/-1 days). Fetuses were administered an infusion of the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, followed by 10 mins of asphyxia induced by complete umbilical cord occlusion. The fetuses then recovered for 3 days. Sixty-one episodes of electrophysiologically defined seizures were identified in five fetuses. Tissue PO(2) (tPO(2)) did not change significantly during short seizures (<3.5 mins), 5.2+/-0.2 versus baseline 5.6+/-0.1 mm Hg (NS), but fell to 2.2+/-0.2 mm Hg during seizures lasting more than 3.5 mins (P<0.001). During prolonged seizures, cortical blood flow did not begin to increase until tPO(2) had begun to fall, and then rose more slowly than the increase in metabolism, with a widening of the brain to blood temperature gradient. In conclusion, in the immature brain, during prolonged, but not short seizures, there is a transient mismatch between cerebral blood flow and metabolism leading to significant cerebral deoxygenation.

Visually Self‐induced Seizures Sensitive to Round Objects

To describe a previously unreported type of self-induced pattern-sensitive seizures in a child. Evaluation of clinical and EEG features. 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. 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.

Meningitis is a common cause of convulsive status epilepticus with fever

Aims: In children with convulsive status epilepticus (CSE) with fever, to determine the likelihood of acute bacterial meningitis (ABM), the proportion that are treated with antibiotics, and the proportion that...

Free Communications: Genetics

Abstract *SumimasaYamashita, *HirokoIwamoto, *MichikoYamada, *MizueIai, *KaoriMasuko, *KazuyoWakabayashi, and †KenjiSugai *Kanagawa Children's Medical Center, Division of Child Neurology, Yokohama ; and †National Center of Neurology and Psychiatry, Musashi Hospital, Division of Child Neurology, Kodaira, Japan. Purpose: We encountered four cases of early myoclonic encephalopathy, consisting of two sets of siblings in two families. In family S, the elder sister is 7 years old now, severely handicapped and demonstrating both uncontrolled myoclonic and short tonic seizures as well as severe hepatic cirrhosis. The younger brother died at age 9 months. In another family O, the elder sister died at age 1 year, and the younger sister died at age 3 months. Each pregnancy was normal, and the deliveries were term, and all infants showed normal birth weight and normal head circumference. None of the infants was severely asphyxiated. Methods: The clinical record of these four cases revealed that the first seizure commenced within 1.5 months after birth, and seizure types were tonic spasms and myoclonic and clonic seizures. A suppression burst pattern was found in all cases at the beginning and then changed to focal or multifocal abnormalities thereafter. None of the cases showed hypsarrhythmia on EEG. In family S, both cases had minor anomalies such as characteristic facial appearances and finger overlapping. Results: Brain MRI showed severe brain atrophy in all cases but none of the cases showed cortical dysgenesis. In family O, the elder sister showed progressive cerebral and cerebellar atrophy, and the younger sister showed myelinating arrest of the cerebral white matter. Developmental milestones were arrested since the neonatal period in four cases. All cases had severe microcephalus, spastic tetraplegia, and severe mental retardation. Laboratory examination revealed no abnormal findings including CBC, chemistry, lactate, pyruvate, amino acids analysis, organic acids analysis, lysosomal enzymes assay using white blood cells, cerebrospinal fluid examination, and urinalysis. Chromosomal study was normal in all cases. Anticonvulsants such as oral high-dose phenobarbital, intravenous phenytoin for focal onset seizures, and zonisamide for apneic attacks were all effective to a moderate extent in some cases but did not reach complete seizure control. Autopsies were performed in two cases. Severe gliosis of cerebral white matter and marked dendritic expansions of cerebellar Purkinje cells were seen in both cases. No storage materials of neuronal and glial cells or laminar structural abnormalities of the cerebral cortex were found. Conclusions: It is important to differentiate from early infantile epileptic encephalopathy, which is characterized by severe asphyxia, brain anomaly, or cortical dysgenesis as a cause, tonic spasm in the seizure pattern of the onset, and alteration to West syndrome. Our cases did not fulfill these points. The main type of seizure was myoclonic or erratic myoclonia. Early myoclonic encephalopathy (EME) is known in cases of nonketotic hyperglycinemia or other inherited metabolic disorders as a cause of the disease. We could not detect metabolic abnormalities in the cases described. However, EME was suspected to have developed because of some genetic factors that might have influenced the development of the infantile nervous system.

Severe lactic acidosis following alcohol related generalised seizures

A 45-year-old alcoholic man presented following several short grand-mal seizures. He was not known to be epileptic. Initial investigations demonstrated a severe lactic acidosis. The rise in lactate was one of the highest levels reported in similar patients. The patient recovered within 4 h of management with oxygen, fluids and sodium bicarbonate. Lactic acidosis following convulsions is often associated with spontaneous resolution and a favourable outcome.

Effects of epileptiform EEG discharges on cognitive function: Is the concept of “transient cognitive impairment” still valid?

In this article we review the existing evidence on the cognitive impact of interictal epileptiform EEG discharges. Such cognitive impairment occurs exclusively in direct relation to episodes of epileptiform EEG discharges and must be distinguished from (post) ictal seizure effects and from the nonperiodic long-term “stable” interictal effects caused by the clinical syndrome or the underlying etiology. Especially in patients with short nonconvulsive seizures, characterized often by difficult-to-detect symptoms, the ictal or postictal effects may be overlooked and the resulting cognitive effects may be erroneously related to the epileptiform EEG discharges. The existing epidemiological data show that the prevalence of cognitive impairment during epileptiform EEG discharges is low. In one study 2.2% of the patients referred to a specialized epilepsy center for EEG recording showed a definite relationship between epileptiform EEG discharges and cognitive impairments (“transient cognitive impairment”). Several studies have sought to analyze to what extent cognitive impairment can be attributed to epileptiform EEG discharges among the other epilepsy factors (such as the effect of the clinical syndrome). These studies show that epileptiform EEG discharges have an additional and independent effect, but this effect is mild and limited to transient mechanistic cognitive processes (alertness, mental speed). This finding concurs with clinical studies that also reported only mild effects. In only exceptional cases are epileptiform EEG discharges the dominant factor explaining cognitive impairment. In addition, some studies have indicated that such mild effects may accumulate over time (when frequent epileptiform EEG discharges persist over years) and consequently result in effects on stable aspects of cognitive function such as educational achievement and intelligence. Hence, the clinical relevance is that early detection of cognitive effects of epileptiform EEG discharges and subsequent treatment may prevent a definite impact on cognitive and educational development. The disruptive effects of epileptiform EEG discharges on long-term potentiation, as established in animal experiments, may be one of the neurophysiological mechanisms underlying this accumulation. In conclusion the concept of “transient cognitive impairment” is still valid, but refinement of methodology has shown that a large proportion of presumed transient cognitive impairment can be attributed to subtle seizures, while interictal epileptic activity accounts for a much smaller part of the cognitive effects than previously thought. In particular cryptogenic partial epilepsies are associated with the risk of cognitive impairment. We hope that increased clinical awareness of this need for early detection will stimulate longitudinal and prospective research that eventually also will provide an answer to the questions of when and how epileptiform discharges that are not part of a seizure need to be treated.

Seizure detection: correlation of human experts.

The description and application of a new, overlap-integral comparison method and the quantification of human vs. human accuracies that can be used as goals for algorithms. Four human experts marked ten 8 h electroencephalography (EEG) records from seizure patients. The seizures varied in origin and type, including complex partial, generalized absence, secondarily generalized and primary generalized tonic-clonic. The traditional any-overlap comparison method is used in addition to the overlap-integral method, which is sensitive to the correct placement of the seizure endpoints. The number of events marked by each reader ranged from 57 to 77. The average any-overlap sensitivity and false positives per hour rate are 0.92 and 0.117. The average overlap-integral correlation, sensitivity and specificity are 0.80, 0.82 and 0.9926. As expected, the correspondence between readers is high, but confounding issues resulted in overlap-integral sensitivities less than 0.5 for 10% of the records. Seven percent of the any-overlap sensitivities are less than 0.5. A comparison of the methods by record shows that the overlap-integral specificity and the any-overlap false positive rate measure different features. There was little variation between readers and they were essentially interchangeable. High seizure rate (many per hour), short seizure durations (<10 s) and long seizure durations (approximately 10 min) with ambiguous offsets can complicate the analysis and result in poor correlation. There may be any number of unmarked events in rigorously marked records and it may be preferable to use records from non-epilepsy patients to compute the false positive rate. The any-overlap and overlap-integral comparison methods are complementary. Correlation between expert human readers can be low on some records, which will complicate testing of seizure detection algorithms.

Correlation between Pre-ictal Bispectral Index and Seizure Duration during Electroconvulsive Therapy under Thiopental Anesthesia

Background: Thiopental anesthesia increases the seizure threshold of patients receiving electroconvulsive therapy. However, excessive neuronal suppression could result in an unacceptably short seizure duration. We sought to identify the correlation between the pre-ictal Bispectral index (BIS) score and seizure duration during electroconvulsive therapy (ECT) under thiopental anesthesia. Methods: Thirty patients with major depressive disorders underwent ECT. Anesthesia was induced by a bolus injection of 2 mg/kg of thiopental. BIS was monitored continuously, and recorded at specific end points, i.e., before anesthesia, just before ECT (pre-ictal BIS), on awaking (eye opening), before discharge to the recovery room and before discharge to the ward. The durations of motor and electroencephalographic seizures were recorded. Results: The BIS score just before ECT was 52 9. Both motor and electro encephalographic seizure durations were positively correlated with the pre-ictal BIS score (R = 0.59 and 0.60, respectively; P 13 and slowly recovered but remained low until discharge to the ward, reflecting post-ictal suppression. Conclusions: Pre-ictal BIS score is positively correlated with seizure duration, but the BIS score may not accurately reflect the depth of sedation after ECT.

Relationships between seizure duration and seizure threshold and stimulus dosage at electroconvulsive therapy: implications for electroconvulsive therapy practice.

Recent studies cast doubt on the usefulness of seizure duration as an index for stimulus dosage adjustment at electroconvulsive therapy (ECT). A retrospective analysis on the relationships between seizure duration and seizure threshold and stimulus dosage was performed for 54 patients who received a standardized ECT dose titration and treatment protocol. Subjects receiving stimulus dosage at seizure threshold had a highly variable motor seizure duration, ranging from 15 to 89 s, and 7.4% of subjects had seizures longer than 60 s. Regression analysis showed that initial seizure threshold and height were independent predictors of motor seizure duration during dose titration and accounted for 34% of its variance. Stimulus dosage was increased by 40-67% between the first and second ECT session; however, 60% of subjects had no lengthening of seizures and motor seizure duration was significantly shorter at the second treatment (mean +/- SD: 35.7 +/- 12.3 vs 31.0 +/- 10.6 s; paired t = 2.9, d.f. = 34, P = 0.006). At the first and second ECT treatment, motor seizure duration was significantly related to stimulus dosage (r = -0.45 and r = -0.41, respectively). Given the negative correlation between seizure duration and stimulus intensity, a policy that recommends an increase of stimulus dosage and its reduction for patients with short and long seizures, respectively, does not necessarily result in 'optimal' seizure duration. A better dosing policy that places less emphasis on seizure duration is proposed.

Results of Multimodality Treatment for 141 Patients with Brain Arteriovenous Malformations and Seizures: Factors Associated with Seizure Incidence and Seizure Outcomes

Previous reports of seizure outcomes after arteriovenous malformation (AVM) treatment have involved single-treatment modality (surgery, radiosurgery, or embolization) series. Such series reflect only selected lesions, of certain sizes, locations, and other clinical and anatomic characteristics, that are amenable to the single therapy, limiting the analysis of those factors. We report the results of AVM treatment using a multimodality approach that we think encompasses a broader spectrum of treatable brain AVMs. We tested for factors associated with seizure presentation and seizure outcomes. Between 1991 and 1999, the multidisciplinary neurovascular unit at Massachusetts General Hospital treated 424 patients with brain AVMs. Treatment consisted of surgical resection, radiosurgery, or embolization, either alone or in combination. One hundred forty-one patients (33%) experienced seizures before treatment. We studied the following factors: sex, age, AVM size, AVM location, occurrence of intracranial hemorrhage, seizure type, duration of seizure history, treatment modality, and AVM obliteration. We tested for statistical associations between these factors and seizure presentation and outcomes. Clinical follow-up monitoring was via mailed questionnaires. When we compared the 141 patients with seizures with the 283 patients who did not experience seizures (total of 424 patients), male sex, age of less than 65 years, AVM size of more than 3 cm, and temporal lobe AVM location were statistically associated with seizures (P < 0.01, P < 0.05, P < 0.0001, and P < 0.01, respectively). Posterior fossa and deep locations were statistically associated with no seizures (P < 0.0001). One hundred ten (78%) of the 141 patients who experienced seizures before treatment responded to the mailed questionnaires, with a mean follow-up period of 2.9 years. A detailed comparison of responders and nonresponders demonstrated no statistically significant differences in pertinent characteristics. As determined with the Engel Seizure Outcome Scale, there were 73 (66%) Class I (free of disabling seizures), 11 (10%) Class II (rare disabling seizures), 1 (0.9%) Class III (worthwhile improvement), and 22 (20%) Class IV (no worthwhile improvement) outcomes. Three patients died during the follow-up period. We tested for factors associated with Engel Class I outcomes. Sex, age, and AVM size were not associated with Class I outcomes. Short seizure history, association of seizures with intracranial hemorrhage, generalized tonicoclonic seizure type, deep and posterior fossa AVM locations, surgical resection, and complete AVM obliteration were statistically associated with Class I outcomes (P < 0.0001, P < 0.05, P < 0.05, P < 0.05, P < 0.001, and P < 0.001, respectively). When only completely obliterated AVMs were considered, there were no statistically significant differences between surgery, radiosurgery, and embolization. Certain factors, as identified in an analysis of a wide spectrum of treatable brain AVMs, can facilitate predictions of the incidence of seizure presentation with AVMs, as well as seizure outcomes after multimodality treatment.

Pre-ictal bispectral index has a positive correlation with seizure duration during electroconvulsive therapy.

Propofol anesthesia increases the seizure threshold of patients receiving electroconvulsive therapy. Excessive neuronal suppression could result in an unacceptably short seizure. We sought to identify the correlation between the pre-ictal bispectral index (BIS) score and seizure duration in patients receiving electroconvulsive therapy under propofol anesthesia. BIS was monitored in 38 psychotically depressed patients. Anesthesia was induced by a bolus injection of 1 mg/kg of propofol. The duration of muscular and electroencephalographic seizure was measured during the therapy. The BIS immediately before the electrical shock was 54 +/- 13. Both muscular and electroencephalographic seizure durations had a positive correlation with pre-ictal BIS (r = 0.68 and 0.73, respectively; P < 0.01). After the electrically induced seizure, BIS decreased to 30 +/- 8, reflecting post-ictal suppression. BIS scores when the patients had awakened after the seizure had a wide variation (range, 29-81; mean, 45; SD, 13). In conclusion, seizure duration has a positive correlation with BIS immediately before electrical shock; however, BIS may not be an accurate predictor of awakening after electrical shock. Pre-ictal bispectral index had a positive correlation with seizure duration and could be useful to prevent an unacceptably short seizure in electroconvulsive therapy under propofol anesthesia.

Anesthesia for electroconvulsive therapy.

Anesthesia for electroconvulsive therapy.

Wisconsin card sorting test in children with temporal lobe epilepsy

To search for the origin of frontal lobe dysfunction identified by the Wisconsin card sorting test (WCST) in temporal lobe epilepsy (TLE) patients, we investigated the WCST performance among 19 children with TLE (with hippocampal atrophy (HA group N=12), without structural lesions (NSL group N=7)), 15 patients with frontal lobe epilepsy (FLE group), and age-matched normal controls (N group). The paired verbal association learning test (PVALT) and Benton visual retention test (BVRT) were also performed. HA group and FLE groups achieved significantly fewer categories and demonstrated more perseverative errors on the WCST than NSL and N groups. In addition, category achievement in WCST showed significant inverse correlation to age at the initial status convulsivus in the HA group ( P<0.05). The achievement on PVALT and BVRT did not show any significant differences between HA and FLE groups ( P>0.05). Thus, the frontal lobe dysfunction in the HA group is found to exist as early as 7 years old, when they seem to have only a short seizure history or to receive a little electrical interference from the temporal lobe focus to the frontal region. These facts would underscore the importance of prefrontal dysfunction persisting from the early insults and only becoming apparent after maturation of the prefrontal region in patients with mesial TLE.

Xantogranuloma juvenil del sistema nervioso central

Juvenile xanthogranuloma (JXG) is a benign histiocytosis affecting mostly skin, although it may also be extracutaneous. Lesions tend to regress spontaneously, but there are cases of bad prognosis.We report the case of a girl aged 3 months with JXG involving skin and, asymptomatically, central nervous system (CNS) and lungs. At age 4 months, the bigger CNS lesion, placed in the right cavernous sinus and whose growth might have had important neurologic repercussions, was excised. After surgery she presented seizures with initial response to antiepileptic drugs. At age 8 and 10 months surgery was again necessary for appearance of a tension pseudoyst in postsurgical bed; a cystoperitoneal shunt was instaured and seizures were controlled. When the patient was 12 months old, the diagnosis of hypothyroidism was established, with a favourable response to levothyroxine. At present, the patient is 2 years 8 months and has a slightly slow neurologic development, with occasional short seizures. Skin lesion is smaller, lung nodules have regressed and, regarding CNS lesions, the bigger has not recurred and the other one remains stable.Some authors propose doing JXG s extension study only when suggested by clinical findings, so long as an effective therapy and the advantage to presymptomatic treatment are not well established. We wonder whether early diagnostic and therapeutic approach to silent deep lesions might lead to a better outcome of patients with JXG, particularly those with CNS involvement.

Drs. Krystal and Weiner Reply

Back to table of contents Previous article Next article Letter to the EditorFull AccessDrs. Krystal and Weiner ReplyANDREW D. KRYSTAL, M.D., M.S., and RICHARD D. WEINER, M.D., PH.D., ANDREW D. KRYSTALSearch for more papers by this author, M.D., M.S., and RICHARD D. WEINERSearch for more papers by this author, M.D., PH.D., Durham, N.C.Published Online:1 Jun 2001https://doi.org/10.1176/appi.ajp.158.6.974AboutSectionsView EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: We appreciate Dr. Swartz’s comments underscoring that the stimulus characteristics used in our study may have affected the results. As he points out, and as we discussed in our article, some reports have suggested that shorter pulse widths and a longer duration of stimuli may be more efficient at eliciting seizures. Such stimulus characteristics might be associated with fewer than 5% of the subjects having ineffective treatments because of short seizures at the maximum available stimulus level. It should be noted, however, that to our knowledge, there have been no published studies that directly address this issue with the use of precise dose-titration methodology, and this possibility therefore remains speculative. Further, other, admittedly flawed, investigations have suggested diminished efficacy with shorter pulse widths.Nonetheless, both MECTA Corporation, whose device we used, and their competitor, Somatics LLC, now produce ECT devices with shorter pulse widths and longer duration stimuli than we employed in our study. Using the newer device made by MECTA Corporation, we have since analyzed new data from 49 subjects. These subjects received a recent clinical index ECT course administered like those in our study, except that a briefer pulse width (1.0 versus 2.0 msec) and a maximum stimulus of longer duration (6.0 versus 2.0 sec) were employed. Fourteen subjects (29%) required the maximum intensity stimulus, and five (10%) had a short seizure at the maximum stimulus level. These preliminary results do not suggest a “substantially lower” failure rate; however, it remains undetermined whether this might be true with even shorter pulse widths.Thus, to our knowledge, no data exist suggesting that our results apply only to the MECTA device used in our study. Of more importance, to our knowledge, no studies contradict our conclusion that there is a need for higher maximum stimulus intensities. This conclusion is also supported by recent compelling independent findings by others (1–3).With respect to the present maximum U.S. stimulus intensity, as we noted, the FDA limited U.S. ECT devices to a maximum intensity before FDA regulation. For MECTA devices, there is a maximum charge of 576 mC versus 504 mC for devices made by Somatics. Since we reported the maximum allowable charge for U.S. devices, the former figure was used. The limitation of 100 J at 220 Ω of impedance referred to by Dr. Swartz reflects a standard once adopted by the International Electrotechnical Commission for ECT devices that has since been withdrawn.The authors are the inventors listed on a U.S. patent that Duke University has licensed to MECTA Corporation. Neither receives royalties from this patent.

Behavioral and electroencephalographic analysis of seizures induced by intrahippocampal injection of granulitoxin, a neurotoxic peptide from the sea anemone Bunodosoma granulifera.

In this study, the behavioral and electroencephalographic (EEG) analysis of seizures induced by the intrahippocampal injection in rats of granulitoxin, a neurotoxic peptide from the sea anemone Bunodosoma granulifera, was determined. The first alterations occurred during microinjection of granulitoxin (8 microg) into the dorsal hippocampus and consisted of seizure activity that began in the hippocampus and spread rapidly to the occipital cortex. This activity lasted 20-30 s, and during this period the rats presented immobility. During the first 40-50 min after its administration, three to four other similar short EEG seizure periods occurred and the rats presented the following behavioral alterations: akinesia, facial automatisms, head tremor, salivation, rearing, jumping, barrel-rolling, wet dog shakes and forelimb clonic movements. Within 40-50 min, the status epilepticus was established and lasted 8-12 h. These results are similar to those observed in the acute phase of the pilocarpine model of temporal lobe epilepsy and suggest that granulitoxin may be a useful tool not only to study the sodium channels, but also to develop a new experimental model of status epilepticus.

Inverse relation between stimulus intensity and seizure duration: implications for ECT procedure.

A retrospective analysis of the effects of electroconvulsive therapy (ECT) was performed for two groups of 11 patients matched according to age (mean age, 52 years), sex, and diagnosis. Group 1 received ECT according to the age-dose protocol; group 2 was treated according to the titration method. A higher dose relative to the seizure threshold appeared to shorten the seizure duration. At the first treatment, the correlation between stimulus intensity and seizure duration was negative. In the titration group, the initial mean charge of 91 mC resulted in a seizure duration of 51 s, whereas in the age-dose group the seizure duration of 31 s was significantly shorter despite a higher mean charge of 312 mC. Seizure duration decreased during the ECT course in the group treated first at low dose (titrated) and then at 2.5 times the initial threshold. High stimulus intensity represented adequate treatment, although it produced short seizures. Thus, seizure duration proved to be an unreliable guideline for effective treatment. Furthermore, focus on seizure duration led to frequent high-dose restimulation in the elderly. The titration method obviates inadequate or excessive charges because the seizure threshold must first be determined.

Postictal diffusion-weighted imaging for the localization of focal epileptic areas in temporal lobe epilepsy.

Diffusion-weighted MR imaging (DWI) is a novel technique to delineate focal areas of cytotoxic edema of various etiologies. We hypothesized that DWI may also detect the epileptogenic region and adjacent areas during the ictal and early postictal periods in patients with temporal lobe epilepsy (TLE). We studied patients with intractable TLE (n = 9), due to hippocampal sclerosis (HS, n = 7), left mesial temporal lobe tumor (n = 1), and of unknown etiology (n = 1). Informed consent was obtained before inclusion in the study. All patients with single short seizures were scanned immediately after EEG-documented seizures (between 45 and 150 min); one of two patients in status was scanned 14 h after cessation of seizures. DWI results were analyzed visually and by calculating apparent diffusion coefficient (ADC) maps. We found significant decreases in ADC postictally in one of six patients with TLE due to HS and single short seizures. One patient with an incompletely resected temporal lobe tumor also exhibited ADC abnormalities. One patient in focal status epilepticus revealed a decrease in ADC, and one patient with a continuous aura had no DWI abnormality. Postictal DWI technique may occasionally help delineate epileptic areas in some patients with TLE. Yield is low in patients with HS and single short seizures: it may be higher in patients with tumor or status epilepticus.