Is a first acute symptomatic seizure epilepsy? Mortality and risk for recurrent seizure

Purpose:   To compare mortality and subsequent unprovoked seizure risk in a population-based study of acute symptomatic seizure and first unprovoked seizure due to static brain lesions.
Methods:   We ascertained all first episodes of acute symptomatic seizure and unprovoked seizure due to central nervous system (CNS) infection, stroke, and traumatic brain injury (TBI). Subjects were residents of Rochester, Minnesota, identified through the Rochester Epidemiology Project's records-linkage system between 1/1/55 and 12/31/84. Information was collected on age, gender, seizure type, etiology, status epilepticus (SE), 30-day and 10-year mortality, and subsequent episodes of unprovoked seizure.
Results:   Two hundred sixty-two individuals experienced a first acute symptomatic seizure and 148 individuals experienced a first unprovoked seizure, all due to static brain lesions. Individuals with a first acute symptomatic seizure were 8.9 times more likely to die within 30 days compared to those with a first unprovoked seizure [95% confidence intervals (CI) = 3.5–22.5] after adjustment for age, gender, and SE. Among 30-day survivors, the risk of 10-year mortality did not differ. Over the 10-year period, individuals with a first acute symptomatic seizure were 80% less likely to experience a subsequent unprovoked seizure compared with individuals with a first unprovoked seizure [adjusted rate ratio (RR) = 0.2, 95% CI = 0.2–0.4].
Discussion:   The prognosis of first acute symptomatic seizures differs from that of first unprovoked seizure when the etiology is stroke, TBI, and CNS infection. Acute symptomatic seizures have a higher early mortality and a lower risk for subsequent unprovoked seizure. These differences argue against the inclusion of acute symptomatic seizures as epilepsy.     

Risk of unprovoked seizure after acute symptomatic seizure: Effect of status epilepticus

We asked whether acute symptomatic status epilepticus (SE) increases the risk for subsequent unprovoked seizure compared with less prolonged acute symptomatic seizure. We also explored whether the risk of unprovoked seizure differs by cause. We ascertained all first episodes of acute symptomatic seizure among residents of Rochester, Minnesota, through the Rochester Project's records-linkage system. Information was collected on seizure duration, age, sex, cause, and subsequent unprovoked seizure. At 10 years of follow-up, the risk of unprovoked seizure was 41% for those with acute symptomatic seizure with SE and 13% for those without SE. Controlling for age, sex, and cause, SE increased the risk for subsequent unprovoked seizure 3.3-fold (95% confidence interval, 1.8–6.1) compared with brief acute symptomatic seizures. Among patients with SE, the risk of unprovoked seizure was increased 18.8-fold for patients with anoxic encephalopathy, 7.1-fold for patients with a structural cause, 3.6-fold for patients with a metabolic cause. The increased risk for unprovoked seizure after SE compared with shorter seizures may be due to SE being a marker for severity of injury, damage caused by SE, or a biological substrate associated with the tendency to experience SE.     

Seizures with Fever After Unprovoked Seizures: An Analysis in Children Followed from the Time of a First Febrile Seizure

Summary: Purpose: To determine how the onset of unprovoked seizures influences recurrence of seizures with fever in children followed from the time of a first febrile seizure.
Methods: In a prospective cohort of children (n = 428) identified at the time of a first febrile seizure, predictors of a second seizure with fever were identified. The occurrence of a first unprovoked seizure was treated as a time-dependent covariate in a Cox regression model rather than as a censoring point as it traditionally has been in the past.
Results: One hundred forty-three (33.4%) children had further seizures. Seven had further seizures with fever only after onset of unprovoked seizures. After adjustment was made for the four previously described predictors of recurrent febrile seizures (age at onset, family history, height of fever, and duration of fever), the onset of unprovoked seizures was associated with a rate ratio of 3.47 (p = 0.0015), indicating a large increase in the risk of further seizures with fever after onset of unprovoked seizures.
Conclusions: Young children who develop unprovoked seizures after a febrile seizure are at substantial risk for further seizures with fever. This may represent part of the spectrum of benign febrile seizures or it may represent the so-called "epilepsy triggered by fever" spectrum. It affects only a small proportion of children with febrile seizures; however, in some children, it may be useful information to consider when making treatment decisions.     

The Prevalence and Incidence of Convulsive Disorders in Children

Summary: Each year, about 150,000 children and adolescents in the United States will come to medical attention for evaluation of a newly occurring seizure disorder of some type. Between 2% and 4% of all children in Europe and the United States experience at least one convulsion associated with a febrile illness before the age of 5 years. The cumulative incidence of febrile convulsions among children ranges from about 1% in China to more than 8% in Japan and 14% in Guam. The peak incidence of a first febrile convulsion occurs in the second year of life. Between 0.5% and 1% of children and adolescents experience a seizure associated with other acute metabolic or neurologic insults; most of these occur in the neonatal period. The incidence of epilepsy (recurrent unprovoked seizures) in children and adolescents seems relatively consistent across all populations studied, ranging from 50 to 100/100,000. The highest incidence of epilepsy is in the first year of life. West syndrome accounts for about 2% of all childhood epilepsy, Lennox-Gastaut syndrome for 1–2%, childhood absence epilepsy (pyknolepsy) for 10–15%, juvenile myoclonic epilepsy for 5%, and idiopathic localization-related epilepsy for 10%. Between 0.5 and 1% of children experience a nonrecurrent, single, unprovoked convulsive episode. Following are the estimated numbers of children and adolescents with newly diagnosed convulsive disorders in the United States for the year 1990: febrile seizures, 100,000; neonatal seizures, 4,000; other provoked seizures, 6,000; single unprovoked seizures, 10,000; and epilepsy, 30,000.     

The Prevalence and Incidence of Convulsive Disorders in Children

Summary: Each year, about 150,000 children and adolescents in the United States will come to medical attention for evaluation of a newly occurring seizure disorder of some type. Between 2% and 4% of all children in Europe and the United States experience at least one convulsion associated with a febrile illness before the age of 5 years. The cumulative incidence of febrile convulsions among children ranges from about 1% in China to more than 8% in Japan and 14% in Guam. The peak incidence of a first febrile convulsion occurs in the second year of life. Between 0.5% and 1% of children and adolescents experience a seizure associated with other acute metabolic or neurologic insults; most of these occur in the neonatal period. The incidence of epilepsy (recurrent unprovoked seizures) in children and adolescents seems relatively consistent across all populations studied, ranging from 50 to 100/100,000. The highest incidence of epilepsy is in the first year of life. West syndrome accounts for about 2% of all childhood epilepsy, Lennox-Gastaut syndrome for 1–2%, childhood absence epilepsy (pyknolepsy) for 10–15%, juvenile myoclonic epilepsy for 5%, and idiopathic localization-related epilepsy for 10%. Between 0.5 and 1% of children experience a nonrecurrent, single, unprovoked convulsive episode. Following are the estimated numbers of children and adolescents with newly diagnosed convulsive disorders in the United States for the year 1990: febrile seizures, 100,000; neonatal seizures, 4,000; other provoked seizures, 6,000; single unprovoked seizures, 10,000; and epilepsy, 30,000.     

Early development of intractable epilepsy in children: a prospective study

BACKGROUND: Little is known about early prediction of intractable epilepsy (IE) in children. Such information could help guide the early use of new therapies in selected patients. METHODS: Children with newly diagnosed epilepsy (n = 613) were prospectively identified from child neurology practices in Connecticut (1993--1997) and followed-up for the occurrence of IE (failure of > or = 2 drugs, > or = 1 seizure/month, over 18 months) [corrected]. Etiology and epilepsy syndromes were classified per International League Against Epilepsy guidelines. RESULTS: The median follow-up is 4.8 years, and 599 (97.7%) have been followed for more than 18 months. Sixty children (10.0%) have met the criteria for IE, including 34.6% with cryptogenic/symptomatic generalized, 2.7% with idiopathic, 10.7% with other localization-related, and 8.2% with unclassified epilepsy (p < 0.0001). After multivariable adjustment for epilepsy syndrome, initial seizure frequency (p < 0.0001), focal EEG slowing (p = 0.02), and acute symptomatic or neonatal status epilepticus (p = 0.001) were associated with an increased risk of IE, and age at onset between 5 and 9 years was associated with a lowered risk (p = 0.03). The absolute number of seizures and unprovoked or febrile status epilepticus were not associated substantially with IE. CONCLUSIONS: Approximately 10% of children meet criteria for IE early in the course of their epilepsy. Cryptogenic/symptomatic generalized syndromes carry the highest risk and idiopathic syndromes the lowest. Half of IE occurs in children with nonidiopathic localization-related syndromes. Initial seizure frequency is highly predictive of IE. By contrast, absolute number of seizures and unprovoked or febrile status epilepticus are not.     

Outcome after prolonged convulsive seizures in 186 children: low morbidity, no mortality

Prolonged convulsive seizures are a common neurological emergency and a potential cause of neuronal damage and functional sequelae. We explored the role of seizure duration and various background factors for neurological sequelae in children with prolonged convulsive seizures. The population-base of this study was all children (age < 16 years) who had been admitted to the Tampere University Hospital, Finland between 1993 and 1999 with convulsive seizures lasting more than 5 minutes. Patients were followed up individually (mean length of follow-up 2 years 1 month, range 0 to 7 years 8 months). All available data on the prolonged seizure episodes and clinical follow-up were analyzed retrospectively by a detailed review of all medical charts and records. In 186 children (94 males, 92 females; mean age 4 years 5 months, SD 3 years 10 months, range 1 month to 15 years 4 months) there were 279 separate convulsive seizure episodes lasting over 5 minutes, yielding an annual incidence of 47.5 out of every 100000 episodes. Seizure aetiology was idiopathic in 26.2% of episodes, febrile in 41.9%, remote symptomatic in 28%, and acute symptomatic in 3.9% of episodes. Mean duration of all seizure episodes was 42.5 minutes (SD 46.1 minutes) and was significantly correlated with the aetiology: shortest in the febrile group (mean 35.4 minutes) and longest in the acute symptomatic group (mean 88.6 minutes; p < 0.001). There was no mortality related directly to these acute seizure episodes. The most common sequela was an onset of epilepsy in 40 children (22%). Permanent neurological sequelae were noted in only four patients (2.2%; mean seizure duration 16 minutes) and non-permanent sequelae in six patients (3.2%; mean seizure duration 38 minutes). Neurological sequelae of prolonged convulsive seizures in children are rare and are related to aetiological factors rather than the duration of a single seizure. The role of acute seizures in the evolution of epilepsy in children remains obscure.     

Short-Term Mortality After a First Episode of Status Epilepticus

Summary: Purpose: Studies evaluating short-term mortality among people who experience status epilepticus (SE) have produced conflicting results. Most studies are derived from clinical series with results affected by unspecified follow-up period and select referral of cases. This study was planned to evaluate short-term mortality after a first episode of SE. Methods: We performed a population-based retrospective cohort study to determine the short-term mortality following a first episode of SE. Between January 1,1965 and December 31, 1984, we studied all first episodes of a febrile SE who received medical attention in Rochester, Minnesota. Cases were followed until death or end of the study (February 1996). Results: Mortality within the first 30 days was 19% (38 deaths out of 201 incident SE). Thirty-four deaths (89%) occurred among those with non febrile acute symptomatic SE, while 4 deaths (11%) occurred among those with unprovoked SE. Within the acute symptomatic group, after adjusting for age, there was a decreased risk of death in women (RR = 0.4; 95% CI: 0.2–0.9). No effect of duration or seizure type was shown after adjusting for other risk factors. Conclusions: One out of 5 subjects with SE died within the first 30 days. Short-term mortality is associated with the presence of an underlying acute etiology. Among acute symptomatic cases, women had a decreased risk of dying.     

Afebrile seizures associated with minor infections: comparison with febrile seizures and unprovoked seizures

This study aimed to demonstrate that afebrile seizures provoked by minor infections constitute a distinct epilepsy syndrome different from febrile seizures and unprovoked afebrile seizures. Of the children who were admitted to hospitals for their first seizure, 1170 had febrile seizures, 286 had provoked seizures, and 125 had unprovoked afebrile seizures. Children with provoked seizures were afebrile at the time of seizure but manifested definite symptoms or signs of minor infection, for example, cough, coryza, vomiting or diarrhea, normal metabolic and cerebrospinal fluid investigations, and no obvious cause for their seizures. The average follow-up was 6.1 years. The Kaplan-Meier estimate of risk at 5 years for subsequent unprovoked afebrile seizures after a first febrile seizure, provoked seizure, or unprovoked afebrile seizure was 1.6%, 5.7%, and 65.7% respectively. All differences were statistically significant (P < 0.0014). In conclusion, afebrile seizures provoked by minor illnesses constitute a distinct type of situation-related seizures, which have not been previously described. Children with provoked seizures have a much lower risk of subsequent unprovoked afebrile seizures than patients with the first afebrile seizure. Careful inquiry for symptoms of minor infections when children present with their first afebrile seizure will help determine the risk for subsequent seizures and the need for antiepileptic drugs.     

Status epilepticus without an underlying cause and risk of death: a population-based study

OBJECTIVE: To determine the independent effect of status epilepticus (SE) on risk of death. DESIGN: Retrospective cohort study. The increased risk of death after SE has been largely ascribed to the underlying medical condition. It is unknown whether SE itself affects risk of death. We address this question by studying idiopathic/cryptogenic SE. SETTING: Population-based study. PARTICIPANTS: We identified all incident idiopathic/cryptogenic unprovoked seizures in the population of Rochester, Minnesota, from January 1, 1955, through December 31, 1984, and observed them until death, loss to follow-up, or the end of the study. MAIN OUTCOME MEASURES: We compared the risk of death in those with a brief unprovoked seizure (<30 minutes) with risk of death in those with an unprovoked seizure of 30 minutes or longer (SE), using Kaplan-Meier and Cox proportional hazards regression. The standardized mortality ratio was also determined. RESULTS: We ascertained 291 people with a first brief unprovoked seizure and 16 with SE. There were 27 deaths among people with seizure and 5 deaths (all aged > 65 years) among people with SE. Compared with people with seizure, the adjusted relative risk for death in those with SE was 2.4 (95% confidence interval [CI], 0.9-6.3) over 10 years. It was increased 5-fold (relative risk, 5.1; 95% CI, 1.6-15.7) among those older than 65 years and 6-fold among those with SE who later developed epilepsy (relative risk, 6.3; 95% CI, 1.5-26.0). Compared with the general population, the standardized mortality ratio was 2.6 (95% CI, 0.8-5.3) for SE and 1.2 (95% CI, 0.8-1.6) for a first seizure of short duration. CONCLUSION: Idiopathic/cryptogenic SE was associated with an increased risk of death among elderly persons and those who later developed epilepsy.