Researchers at the University of Cincinnati, OH, examined medical records of 75 children, aged 3 months to 21 years (mean age 7.8 years), for prevalence of nonconvulsive status epilepticus (NCSE) by searching a clinical EEG database (n=18) or consecutive inpatient EEG referrals for NCSE over an 8-month period (n=57). NCSE was identified in 26 patients (35%) and in 8 of 57 (14%) patients referred for possible NCSE (>50% from outside the ICU). An acute etiology for encephalopathy was determined in 31 of 75 (41%) patients; it was an extra CNS infection and fever in 12, CNS infection in 8, and hypoxia in 12. Less than half the patients with NCSE were critically ill; 4 NCSE patients (15%) died, and 8 (31%) had significant neurologic morbidity on discharge. Compared to patients identified with NCSE, of the 49 patients without NCSE, 4 (8%) died and 2 (4%) had neurologic morbidity. The majority of patients (15 of 26, 58%) identified with NCSE were in the neurology service. A clinical seizure was witnessed in 24 (92%) patients with NCSE. Of 57 patients with acute neuroimaging within 24 hours of EEG, 20 showed abnormalities including multifocal cortical edema and acute hydrocephalus. Clinical seizures and acute neuroimaging abnormality were associated with an 82% probability of NCSE. NCSE was accompanied by electrographic or electroclinical seizures within the first hour of monitoring; the median duration of monitoring was 11.5 hours. Continuous EEG monitoring is recommended in children with acute encephalopathy. [1]

COMMENT. Risk factors for NCSE in children include a prior clinical seizure and acute cortical imaging abnormality. When both of these variables were present, the probability of NCSE was high (82%). If NCSE is suspected, continuous EEG monitoring is important not only in high-risk neonates in the ICU but also in children and adolescents with disturbed consciousness and symptoms of encephalopathy. The Cincinnati investigators defined NCSE as continuous 30-minute electrographic seizure activity with non-convulsive clinical symptoms or repeated briefer electrographic seizures comprising at least 30 minutes of a 1-hour period. [1]

A NCSE etiological classification included metabolic disorders, coma, acute cerebral lesions, and preexisting epilepsy [2]. NCSE constitutes about 25-50% of all cases of status epilepticus. In comatose patients, NCSE diagnosis is often difficult and potentially fatal if untreated. The EEG may show a variety of rhythmic or periodic patterns, some of unclear significance. Of 19 pediatric patients with NCSE identified from the database of the Columbia University Epilepsy Center, 6 had periodic lateralized epileptiform discharges (PLEDS), and 1 had generalized PEDS. Periodic discharges were associated with worse outcome [3]. The most frequent etiology of NCSE in this study was acute hypoxic-ischemic encephalopathy (26%); other causes included metabolic (21%), infection (16%), AED change (16%), refractory epilepsy (11%), and intracranial hemorrhage (11%). Prompt recognition of NCSE by continuous EEG monitoring should lead to early treatment and improved prognosis.