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

Abstract

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.

Long‐term outcomes of status epilepticus: A critical assessment

“…In comparison, the risk of subsequent epilepsy after a single seizure is 40%‐50% 31, 32. In terms of epilepsy severity after SE, epilepsy becomes refractory in 15%‐25% of children after SE, which is not markedly different from the proportion of refractory cases in the general epileptic population 6, 33. In a population‐based series of 115 children with epilepsy, those who had SE, when compared with those who did not have an SE event, had a lower probability of epilepsy remission (55% vs 80%; risk ratio = 0.58, 95% confidence interval = 0.34‐0.99, P  =   0.044).…”

“…In 15 pediatric studies, SE was defined as any seizure lasting >30 minutes or recurrent seizures lasting a total of >30 minutes without the subject fully regaining consciousness by most studies, except for one paper that used a 5‐minute limit 6. In 21 studies including adults, definitions were more variable, including 30‐minute seizure duration limits,7, 8, 9, 10, 11, 12, 13 and 5‐minute clinical seizure duration or more than two seizures without return to baseline between seizures 14, 15, 16, 17, 18, 19.…”

“…In pediatric patients, this risk ranges from 5% to 36% 6, 26, 27, 28, 29. In mixed populations of adults and children, subsequent epilepsy after SE may occur in 22%‐41%,14, 30 which is less than in patients with history of RSE, who have a 87.5% risk of subsequent epilepsy 14.…”

“…Cognitive outcomes are usually evaluated based on clinical judgment or measured using a wide variety of neuropsychological tests. The underlying etiology is the main factor associated with long‐term cognitive outcome in children,6, 28, 33, 36, 38 with symptomatic SE28, 36, 38 or progressive encephalopathy36 contributing to increased risk. Other factors are young age at the time of SE28, 36, 38 and neuroimaging abnormalities28 (Table 1).…”

“…Most adult studies focus on functional rather than cognitive outcomes using standardized scales like the modified Rankin Score and the Glasgow Outcome Scale, with functional deficits seen in 21‐61%,16, 20, 21, 43, 44 and these could be more severe in RSE20 or SRSE (67%) 16. Functional outcomes in children are mostly based on clinical impression, yielding a wide spectrum of functional impairment after SE from 0% to 79%,6, 17, 24, 26, 27, 28, 29, 35, 36, 38, 45 and this range may also be related to different definitions and assessment of impairment, and often lack of good baseline information. The evaluation of long‐term cognitive outcomes is further complicated by evolution over time in some cases, and in particular outcomes in children are often not static as development progresses.…”