Nonconvulsive Status Epilepticus in Childhood Localization-Related Epilepsy

PURPOSE: To report on three children with localization-related epilepsy who exhibited minor seizures (atypical absences, brief atonic, and myoclonic) and nonconvulsive status epilepticus (NCSE) consisting of these minor seizures, and to elucidate their significance. METHODS: We studied the electroclinical characteristics of these children. Ictal electroencephalograms (EEGs) of NCSE were evaluated by using simultaneous video-EEG-electromyogram (EMG) polygraphic recordings. RESULTS: All patients began to have partial seizures between the ages of 6 months and 2 years 7 months, with minor seizures appearing later, between the ages of 1 year 11 months and 6 years 6 months. These minor seizures evolved into NCSE. Complex partial seizures remained after suppression of the minor seizures. Interictal EEGs taken when the minor seizures appeared showed excessive diffuse epileptic discharges in addition to multifocal spike-waves. Before and after suppression of the minor seizures, focal epileptic discharges predominated on the EEGs. On ictal EEGs of brief atonic and myoclonic seizures, diffuse spike-wave and polyspike-wave bursts were detected. Ictal EEGs of the atypical absences revealed diffuse spike-wave bursts mixed with irregular high-voltage slow waves, often interspersed with brief atonic and myoclonic seizures. When atypical absences lasted for a long time, patients manifested NCSE. Polytherapy might be related to the occurrence of minor seizures and NCSE, because all patients were treated with polytherapy at their appearance, and simplification of antiepileptic drug (AED) therapy seemed to be effective. CONCLUSIONS: We concluded that this NCSE is a type of atypical absence status which is an age-dependent, transient, electroclinical condition. The mechanism of occurrence of these minor seizures might be related to secondary bilateral synchrony.     

Utility of the Scalp-Recorded Ictal EEG in Childhood Epilepsy

PURPOSE: To evaluate the usefulness of the scalp-recorded ictal EEGs in diagnosing childhood epilepsy. METHODS: We analyzed the ictal EEGs of 259 seizures in 183 patients who visited the department of child neurology, Okayama University Medical School, during the past 6 years. RESULTS: We divided all seizures into the following four categories, according to the diagnostic usefulness of ictal EEGs in determining the seizure type: 1. (a) Ictal EEGs confirmed the diagnosis of the seizure type based on seizure symptoms (101 seizures); (b) Ictal EEGs aided in the classification of the seizure type based on the seizure symptoms (101 seizures); (c) Ictal EEGs corrected errors in the classification (37 seizures); and (d) Ictal EEGs revealed previously unreported/undocumented seizure type (20 seizures). 2. Of the 37 misdiagnosed seizures (group C), 11 were nonepileptic seizures misdiagnosed as epileptic seizures, eight were complex partial seizures (CPS) misdiagnosed as the other seizure types, and 10 were other seizure types misdiagnosed as CPSs. 3. Of the 20 previously unreported/undocumented seizures (group D), nine were myoclonic seizures, five were absence seizures, five were CPS, and one was tonic spasms. 4. Seventy-two patients had CPS. Among them, 11 patients showed no epileptic spikes in their interictal EEG recordings. Therefore, ictal recordings confirmed the diagnosis of epilepsy. CONCLUSIONS: Ictal EEG recording is a very useful diagnostic tool not only for determining seizure types, but also for uncovering the existence of the unsuspected seizure types. It supplies the physician with useful information for the classification and the treatment of epilepsy. In particular, ictal EEGs are useful in diagnosing patients with CPS.     

中老年复杂部分性发作癫痫持续状态的临床特征及误诊分析

目的 分析中老年复杂部分性发作癫痫持续状态(CPSE)的临床特点及误诊原因.方法 收集广州医学院第二附属医院神经内科自2008年1月至12月收治、曾被外院误诊的中老年CPSE患者的临床资料,进行视频脑电图(EEG)、头颅MR、生化检查,根据国际抗癫痫联盟的CPSE诊断标准进行诊断,并随访3个月以上. 结果 本组患者7例,均为女性,其中额叶癫痫(FLE)2例,颞叶癫痫(TLE)5例;CPSE患者临床症状和视频EEG表现多样化;经抗癫痫药物(AEDs)治疗后3例至少3个月无发作,3例仍有CPSE发作,1例仍有反复CPSE. 结论 由于CPSE患者临床症状和EEG表现欠典型,常合并其他系统疾病和社会因素的影响易被误诊,应及早做视频EEG检查以明确诊断;口服AEDs治疗可取得良好效果.     

Five pediatric cases of ictal fear with variable outcomes

Purpose: Ictal fear is an uncommon condition in which fear manifests as the main feature of epileptic seizures. The literature has suggested that ictal fear is generally associated with poor seizure outcomes. We wanted to clarify the variability in seizure outcome of children with ictal fear. Subjects and methods: We identified five pediatric patients with ictal fear who were followed up on at Okayama University Hospital between January 2003 and December 2012. We retrospectively reviewed their clinical records and EEG findings. Results: The onset age of epilepsy ranged from 8 months to 9 years and 10 months. The common ictal symptoms were sudden fright, clinging to someone nearby, and subsequent impairment of consciousness, which were often accompanied by complex visual hallucinations and psychosis-like complaints. Ictal fear, in four patients, was perceived as a nonepileptic disorder by their parents. Ictal electroencephalograms (EEG) of ictal fear were obtained in all patients. Three showed frontal onset, while the other two showed centrotemporal or occipital onsets. Two patients were seizure free at last follow-up, while seizures persisted in the other three. A patient with seizure onset during infancy had a favorable outcome, which was considered to be compatible with benign partial epilepsy with affective symptoms. Conclusion: Ictal fear is not always associated with a symptomatic cause or a poor seizure outcome. It is quite important to make a correct diagnosis of ictal fear as early as possible to optimize treatment.     

Role of immediate postictal diffusion-weighted MRI in localizing epileptogenic foci of mesial temporal lobe epilepsy and non-lesional neocortical epilepsy.

OBJECTIVE: To determine whether meaningful changes in signal intensity or in the apparent diffusion coefficient of water (ADC) in the ictal onset zone can be detected through immediate postictal and interictal diffusion-weighted magnetic resonance imaging (DWMRI) in patients with localization-related epilepsy. METHOD: In randomly selected 10 medial and lateral temporal lobe epilepsy (TLE) and four extratemporal epilepsy patients, DWMRI was performed immediately after a seizure and during the interictal period. All 14 patients were non-lesional except for hippocampal sclerosis detected on MRI. The mean time interval from seizure onset to postictal DWMRI was 81 min. Regions of interest (ROI) were selected in both the cortex, which was believed to be the ictal onset zone, and the corresponding anatomical region of the contralateral hemisphere in the postictal and interictal DWMRI. The mean ADC measured from all ROIs was compared. Ictal onset zones were determined by ictal electroencephalography (EEG) and seizure semiology. RESULTS: On visual inspection of postictal and interictal DWMRI, signal changes in the ictal onset zone could be identified in only one patient with medial TLE. The mean ADC values from the ictal onset zones were not significantly different from those of the corresponding contralateral regions of the cortices in both postictal and interictal DWMRI. However, the postictal ADC values of the epileptogenic foci of neocortical epilepsy or neocortical temporal portion of TLE without hippocampal sclerosis were decreased compared with interictal ones in whom both interictal and postictal DWMRIs were obtained (P = 0.028). CONCLUSION: Our results demonstrate that water diffusion can change even after a single seizure in non-lesional neocortical epilepsy.     

Status epilepticus and tiagabine therapy revisited

PURPOSE: To determine whether antiepileptic treatment with tiagabine (TGB) is associated with an increased frequency of nonconvulsive status epilepticus (NCSE) in patients with refractory epilepsy. METHODS: We reviewed retrospectively the medical and EEG records of all inpatients with refractory localization-related epilepsy at the National Society for Epilepsy treated with TGB between January 1997 and December 2000. Clinical and electroencephalographic (EEG) data before, during, and after TGB therapy were evaluated in those patients who experienced a deterioration in seizure control suggestive of NCSE. Frequency of NCSE was determined in a comparable, non-TGB-treated patient population. RESULTS: Seven (7.8%) of 90 TGB-treated patients were identified who experienced episodes of electroclinically confirmed NCSE. Serial EEGs showed deterioration during TGB treatment, with resolution of abnormality on discontinuation of TGB in all seven patients. During the same observation period, 32 (2.7%) of 1,165 non-TGB-treated patients developed electroclinically defined NCSE. CONCLUSIONS: Treatment with TGB is associated with an increased frequency of NCSE in patients with refractory localization-related epilepsy.     

Lamotrigine intoxication provoking status epilepticus in an adult with localization-related epilepsy

BACKGROUND: Various anticonvulsant medications have been associated with paradoxical aggravation of epileptic seizures in therapeutic doses and toxic concentrations. Lamotrigine has been reported to exacerbate seizures and myoclonic seizures in generalized epilepsy in a child with localization-related epilepsy. OBJECTIVE: To describe lamotrigine intoxication paradoxically producing status epilepticus in an adult with localization-related epilepsy. DESIGN: Observational case report. SETTING: Neurology service, inpatient hospitalization, and outpatient follow-up in a neurology clinic. PATIENT: A patient with known localization-related epilepsy who ingested an overdose of lamotrigine tablets in a suicide attempt. INTERVENTION: None. MAIN OUTCOME MEASURE: Observation of the course of the patient's reaction to lamotrigine intoxication, monitoring of lamotrigine levels, and monitoring of ictal and postictal status. RESULTS: The patient developed a prolonged convulsive status epilepticus, which was eventually controlled with benzodiazepines. The patient also developed transient obtundation and severe ataxia, all of which resolved completely within 96 hours. CONCLUSIONS: To our knowledge, in addition to being the first case report to describe convulsive status epilepticus after lamotrigine intoxication, this is the first report of the proconvulsant effect of lamotrigine in a case of localization-related epilepsy in an adult. The effects of accidental or suicidal ingestion of lamotrigine tablets seem to be reversible.     

Characteristic phasic evolution of convulsive seizure in PCDH19‐related epilepsy

PCDH19‐related epilepsy is a genetic disorder that was first described in 1971, then referred to as “epilepsy and mental retardation limited to females”. PCDH19 has recently been identified as the responsible gene, but a detailed characterization of the seizure manifestation based on video‐EEG recording is still limited. The purpose of this study was to elucidate features of the seizure semiology in children with PCDH19‐related epilepsy. To do this, ictal video‐EEG recordings of 26 convulsive seizures in three girls with PCDH19‐related epilepsy were analysed. All seizures occurred in clusters, mainly during sleep accompanied by fever. The motor manifestations consisted of six sequential phases: “jerk”, “reactive”, “mild tonic”, “fluttering”, “mild clonic”, and “postictal”. Some phases were brief or lacking in some seizures, whereas others were long or pronounced. In the reactive phase, the patients looked fearful or startled with sudden jerks and turned over reactively. The tonic and clonic components were less intense compared with those of typical tonic‐clonic seizures in other types of epilepsy. The fluttering phase was characterised initially by asymmetric, less rhythmic, and less synchronous tremulous movement and was then followed by the subtle clonic phase. Subtle oral automatism was observed in the postictal phase. The reactive, mild tonic, fluttering and mild clonic phases were most characteristic of seizures of PCDH19‐related epilepsy. Ictal EEG started bilaterally and was symmetric in some patients but asymmetric in others. It showed asymmetric rhythmic discharges in some seizures at later phases. The electroclinical pattern of the phasic evolution of convulsive seizure suggests a focal onset seizure with secondary generalisation. Based on our findings, we propose that the six unique sequential phases in convulsive seizures suggest the diagnosis of PCDH19‐related epilepsy when occurring in clusters with or without high fever in girls. [Published with video sequences online]     

The clinical usefulness of ictal surface EEG in neocortical epilepsy

PURPOSE: Localizable scalp EEGs, during ictal episodes, appear to be rare in neocortical epileptic syndromes. However, studies based on large numbers of patients are also rare. This study aims to identify the characteristic patterns of variable neocortical epilepsies and to evaluate their clinical usefulness in the localization of epileptogenic focuses. METHODS: We retrospectively assessed 394 noninvasive ictal recordings from 86 patients who subsequently underwent invasive study and resective surgery. Ictal EEGs were recorded using a video-EEG monitoring system with electrodes placed according to the International 10-20 system, with additional anterior temporal electrodes. The ictal recordings were analyzed according to localizing accuracy and frequency characteristics. The durations of discrete or regional ictal rhythms were also measured. RESULTS: The percentage of discrete or regional EEGs was 23% in frontal lobe epilepsy, 52% in lateral temporal lobe epilepsy, 70% in occipital lobe epilepsy, and 10% in parietal lobe epilepsy. In order of frequency, the localizable ictal rhythms were theta, beta, alpha, delta, and rhythmic spike-and-wave. The duration of discrete or regional ictal rhythms was significantly shorter in frontal lobe epilepsy and parietal lobe epilepsy than in other epilepsies. Ictal beta activity was the most common rhythm in discrete-patterned EEGs. Structural lesions found on MRI did not significantly affect the localization of epileptogenic focuses in the patients. The type of seizure was not related to the degree of localization, with the exception of simple partial seizure. CONCLUSIONS: Ictal surface EEG was clinically helpful in the localization of epileptogenic focuses in at least some neocortical epileptic syndromes.     

Panayiotopoulos syndrome with convulsive status epilepticus at the onset: A long-term study

PurposeTo better define the convulsive status epilepticus (CSE) as a possible manifestation at the onset of Panayiotopoulos syndrome (PS) and to assess its prognostic value in these children.MethodsChildren with CSE and diagnostic criteria of PS were identified, followed clinically and compared with a group of patients with PS without CSE from 1993 to 2012.ResultsWe identified 37 patients with CSE at the onset of PS. During the same period we identified 72 children with autonomic symptoms of PS without CSE. The first episode of CSE occurred at a mean age of 6.5 years. Generalized clonic seizures were the most common ictal event and one-third of the patients required admission to Intensive Care Units. Interictal EEGs showed occipital spike activity in 31 (83.7%) subjects. Only 14 (37.8%) patients were treated with valproic acid and for two of them (5.40%) it was necessary to administer other drugs. There were no intractable cases. The overall prognosis was excellent. After the first event, 15 subjects (40.54%) experienced at least another typical PS seizure, but all patients were seizure free at the last follow-up.ConclusionCSE is not uncommon in PS and it may occur at the onset of benign childhood epilepsy, without leading to a poor prognosis.     

The EEG and Prognosis in Status Epilepticus

Summary: Purpose: To examine the relation between specific EEG features and clinical outcome, determine whether a predictable sequence of EEG patterns exists during status epilepticus (SE), and examine the relation between periodic epileptiform discharges (PEDs) and SE.
Methods: EEG records of 50 patients with SE admitted to Graduate Hospital between January 1990 and July 1995 were reviewed. Ictal EEGs were available in 72%; 28% had only postictal EEGs. Poor outcome was defined as death or persistent vegetative state, and good outcome as all others. Fisher's Exact test, x², and t tests were performed for data analysis.
Results: Of 50 patients, 72% had a good outcome and 28%, a poor outcome. If PEDs were present at any time during or after SE, outcome tended to be worse (p = 0.053). With PEDs, eight (44%) of 18 had a poor outcome; without PEDs, six (19%) of 32 had a poor outcome. Etiologies for SE did not substantially differ in patients with or without PEDs, and structural abnormalities were not more associated with the presence of PEDs. PEDs were seen both early and late, during and after SE. Other EEG characteristics (lateralized vs. bilateral symmetric ictal EEG, discrete vs. continuous ictal activity, and postictal focal slowing) did not relate to outcome. No predictable sequence of EEG changes was found during SE.
Conclusions: PEDs are the only EEG feature related to outcome in SE and are associated with poor outcome independent of etiology.     

"Obtundation Status (Dravet)" Caused by Complex Partial Status Epilepticus in a Patient with Severe Myoclonic Epilepsy in Infancy

Summary: Purpose : We report a 1-year 7-month-old boy with severe myoclonic epilepsy in infancy (SME) who exhibited complex partial status epilepticus (CPSE), which was confirmed by ictal video-EEG analysis. This boy first had a hemi-convulsion in a hot bath at age 3 months. Thereafter, he exhibited both partial and generalized seizures that were extremely intractable. At age 9 months, he had a prolonged episode of impaired consciousness that fit the "obtundation status in SME" defined by Dravet et al.
Methods and Results : Ictal EEG revealed persisting irregular spike-and-wave complexes over the left hemisphere, predominantly in the occipitotemporal area, and confirmed CPSE. The EEG abnormalities with decreased level of the consciousness continued -6 h after onset of the symptoms even with AED administration.
Conclusions : Because SME features both generalized and focal seizures, both types of nonconvulsive status may be seen in SME. Although Dravet et al. already reported long-lasting atypical absences in patients with SME as "obtundation status," we demonstrated CPSE in an infant with SME who exhibited a prolonged stuporous state.     

Non convulsive status epilepticus after replacement of valproate with lamotrigine

Purpose: Lamotrigine (LTG) and valproate (VPA) are widely used in the treatment of generalized epilepsies. Nevertheless seizure aggravation with LTG has been reported in juvenile myoclonic epilepsy and epilepsy with myoclonic absences. The aim of this study was to describe clinical features and EEG findings in patients with non convulsive status epilepticus (NCSE) after replacement of VPA with LTG. Method: Retrospective analysis of three identified patients in a large university hospital. Results: We describe three adult patients aged 39, 50 and 75 years, who developed non-convulsive status epilepticus (NCSE) after replacement of VPA with LTG. The episodes of NCSE presented as an acute confusional state with mild myoclonus. Ictal EEG showed generalized spike-wave or polyspike wave activity. The clinical symptoms and the EEG responded promptly to IV benzodiazepines and patients remained well controlled with dose reduction of LTG (in one patient) or discontinuation of LTG (in two patients). Conclusion: The reported episodes of NCSE in these patients with generalized epilepsy may be either due to a possible paradoxical reaction to LTG or due to a withdrawal effect of VPA. Received: 5 November 2001, Received in revised form: 8 April 2002, Accepted: 23 April 2002 Correspondence to Eugen Trinka, MD     

Ictal headache: headache as first ictal symptom in focal epilepsy

Headache may be associated with seizures as a preictal, ictal, or postictal phenomenon, but it is often neglected because of the dramatic neurological manifestations of the seizure. Headache can also be the sole or predominant clinical manifestation of epileptic seizures, although this is a relatively rare condition. We describe two cases of focal symptomatic drug-resistant epilepsy with headache as the first ictal symptom. In both cases, the headache, which lasted a few seconds, was contralateral to the ictal discharge and did not have the clinical features of migraine. Ictal headache is a rare epilepsy symptom that can help to localize ictal EEG discharges. Recently, the term ictal epileptic headache has been proposed in cases in which headache is the sole ictal epileptic manifestation Diagnosis requires the simultaneous onset of headache with EEG-demonstrated ictal discharges.     

How common is ictal hypoxemia and bradycardia in children with partial complex and generalized convulsive seizures?

Purpose: Autonomic effects of seizures, including cardiorespiratory abnormalities, may be involved in sudden unexpected death in epilepsy (SUDEP). The purpose of this study was to determine the prevalence and risk factors for ictal hypoxemia (oxygen saturation <90%) and ictal bradycardia (heart rate < second percentile for age) in children during recorded seizures. Methods: The medical records of children admitted to our Epilepsy Monitoring Unit (EMU) between November 1, 2007 and March 13, 2009 were reviewed. Children selected for this study had at least one partial complex or generalized convulsive seizure with recorded oximetry and/or heart rate data. Results: Forty‐nine children were identified and 225 seizures were analyzed. Ictal hypoxemia was observed in 48.9% of children and 26.8% of seizures. Ictal hypoxemia was significantly more likely to occur during generalized versus nongeneralized seizures (43.9% vs. 18.9%) and when tapering antiepileptic drugs (AEDs) (75% vs. 35.5%). For partial complex seizures, there was an association between ictal hypoxemia and prolonged seizure duration. There was no correlation between ictal hypoxemia and partial seizure onset localization or lateralization. Ictal bradycardia occurred in 8.2% of children and 3.7% of seizures. Ictal bradycardia was observed solely with partial complex seizures of extratemporal onset. Due to the low prevalence of ictal bradycardia, these findings were not statistically significant. Discussion: Ictal hypoxemia is common, particularly in the setting of generalized tonic–clonic seizures, prolonged partial complex seizures, and when AEDs are tapered. In contrast to previous ictal bradycardia studies, ictal bradycardia occurred exclusively in extratemporal partial complex seizures in this cohort.     

Ictal headache: Headache as first ictal symptom in focal epilepsy

Headache may be associated with seizures as a preictal, ictal, or postictal phenomenon, but it is often neglected because of the dramatic neurological manifestations of the seizure. Headache can also be the sole or predominant clinical manifestation of epileptic seizures, although this is a relatively rare condition. We describe two cases of focal symptomatic drug-resistant epilepsy with headache as the first ictal symptom. In both cases, the headache, which lasted a few seconds, was contralateral to the ictal discharge and did not have the clinical features of migraine. Ictal headache is a rare epilepsy symptom that can help to localize ictal EEG discharges. Recently, the term ictal epileptic headache has been proposed in cases in which headache is the sole ictal epileptic manifestation Diagnosis requires the simultaneous onset of headache with EEG-demonstrated ictal discharges.     

Late postictal residual perfusion abnormality in epileptogenic zone found on 6-hour postictal SPECT

BACKGROUND: Temporal evolution of regional hyperperfusion in the late postictal stage in epilepsy has not been clearly defined. OBJECTIVE: To establish the late temporal evolution of the perfusion in epileptogenic zones using 6-hour postictal SPECT. METHODS: Ictal 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT was performed in 10 patients with intractable epilepsy (4 temporal lobe epilepsy, 6 neocortical epilepsy) followed by delayed acquisition and another 6-hour postictal SPECT after reinjection of 99mTc-HMPAO. The delayed acquired SPECT was subtracted from the reinjection SPECT to yield the 6-hour postictal SPECT. Interictal SPECT was acquired on another day. Late postictal perfusion was examined visually, and asymmetric indexes were compared with each other on ictal, 6-hour postictal, and interictal SPECT. RESULTS: Ictal SPECT images of delayed acquisition were visually and quantitatively similar to those of early acquisition. In 7 of 10 patients, 6-hour postictal SPECT showed hyperperfusion. In one patient, the 6-hour postictal SPECT image showed less perfusion than the interictal SPECT image in the epileptogenic zone. CONCLUSIONS: Late postictal hyperperfusion was found in more than half of the patients. Postictal perfusion abnormalities did not come back to the interictal phase 6 hours after ictus and these were identified on ictal/postictal 99mTc- HMPAO SPECT.     

États de mal épileptiques non convulsifs

Non convulsive confusional status epilepticus is classically divided on the basis of the ictal EEG into absence status (AS) and complex partial status epilepticus (CPSE). The clinical presentation is often insufficient to establish diagnosis and emergency EEG is required. AS is a polymorphic condition that can complicate many epileptic syndromes. In half of cases, confusion of varying intensity is associated with bilateral periocular myoclonias. Clinical and EEG normalization is obtained after intravenous benzodiazepine injection. From a nosographic point of view, four types of AS may be recognized. Typical AS occurs as part of an idiopathic generalized epilepsy. Atypical AS occurs in patients with symptomatic or cryptogenic generalized epilepsies. “De novo” AS of late onset is characterized by toxic or metabolic precipitating factors in middle-aged subjects with no previous history of epilepsy. AS with focal characteristics occurs in subjects with a preexisting or newly developing partial epilepsy, most often of extratemporal origin. Most cases are transitional forms between these four entities. CPSE is characterized by continuous or rapidly recurring complex partial seizures which may involve temporal and/or extratemporal regions. Cyclic disturbance of consciousness is characteristic of CPSE of temporal lobe origin, which requires vigorous treatment to prevent recurrence or cognitive sequelae. CPSE of frontal lobe origin is a diagnostic challenge: it is rare, the symptoms are unusual, and extensive documentation is required. A focal, frontal lesion is discovered in one third of cases.     

Acute Prolonged Confusion in Later Life as an Ictal State

Six patients ranging in age from 42 to 69 with no prior history of seizure disorder presented an acute prolonged or intermittent confusional state, with or without psychotic symptoms, as an ictal manifestation. The EEGs demonstrated protracted generalized spike and wave discharges, but full diagnostic evaluation disclosed no evident cause for the seizures. All promptly responded to small amounts of intravenous diazepam and subsequent oral phenytoin and phenobarbital. Three of the six patients had focal spike or sharp wave discharges on EEGs recorded subsequently, suggesting that the episodes may reflect secondary generalized seizures in some cases. These cases do not fit in the classic category of petit mal status and appear to be a distinct entity.     

Prospective Population-Based Study of Intermittent and Continuous Convulsive Status Epilepticus in Richmond, Virginia

PURPOSE: Previous work suggested that there is a lower mortality for convulsive status epilepticus (SE) with intermittent seizures (intermittent SE) as opposed to SE with continuous seizure activity (continuous SE). A plausible hypothesis to explain this difference is that the shorter ictal time in intermittent SE is responsible for the lower mortality in this group. This study investigates the relative contributions of total ictal time and SE duration to the differing mortalities of intermittent and continuous SE. METHODS: Six hundred forty-five cases of prospectively identified convulsive SE were examined. Nonparametric statistical methods were used to compare continuous SE and intermittent SE variables. Multivariate logistic regression analyses were used to determine which factors were most highly associated with mortality. Intermittent SE cases were analyzed to evaluate the relative contributions of ictal time versus SE duration to mortality. RESULTS: Intermittent SE had a significantly lower mortality than continuous SE (19.6 vs. 31.4%; p < 0.001) in adults but not in children. Intermittent and continuous SE durations did not significantly differ in adult cases but did differ in pediatric cases. Ictal time was significantly shorter than SE duration for intermittent SE in both adults and children. After adjusting for age, etiology, and SE duration, SE type (continuous SE vs. intermittent SE) was shown to have an independent effect on mortality in adults. The relative risk of mortality for continuous SE was 1.79 times that of intermittent SE (p = 0.04). After controlling for SE duration, ictal time did not significantly affect mortality in adults. CONCLUSIONS: Intermittent and continuous convulsive SE were common in both pediatric and adult populations. Intermittent SE had a significantly lower mortality than did continuous SE. This difference in mortality was not completely explained by differences in SE duration, total ictal time, etiology, or age. Further research is needed to identify the factor(s) contributing to the significant difference in mortality between intermittent SE and continuous SE.