The role of continuous electroencephalography in childhood encephalitis

Background Seizures are a known complication of encephalitis. We sought to determine the incidence of seizures and the relative utility of routine and continuous electroencephalography in children with suspected encephalitis. Methods Records from all 217 children (ages 0-20 years, enrolled 2004-2011) from our institution who had diagnostic samples sent to the California Encephalitis Project were reviewed. Results One hundred children (46%) had at least one seizure observed clinically or recorded on electroencephalography. Diffuse abnormalities (e.g., generalized slowing) were more common than focal or epileptiform abnormalities (88.9% vs 63.2% and 57.3%, respectively; P < 0.0001), but focal and epileptiform abnormalities were more correlated with seizures (91.0% [P = 0.04] and 89.2% [P = 0.05], respectively vs 76.9%). Fifty-four patients (25%) had at least 1 day of continuous electroencephalography. When used, continuous electroencephalography recorded a seizure in more than half of patients. Six children had no recognized seizure (clinical or electrographic) before continuous electroencephalography was performed. Twenty-two children (10%) had a seizure recorded by continuous electroencephalography after routine electroencephalography did not record a seizure. Overall, continuous electroencephalography was more likely to capture a seizure, capture a subclinical seizure, or rule out a concerning event as a seizure than routine electroencephalography (all comparisons P < 0.0001). Conclusions Children with suspected encephalitis are at high risk for seizures. Continuous electroencephalography is better able than routine electroencephalography to determine whether seizures are present. Further, continuous electroencephalography can guide treatment by classifying a clinical event as seizure or seizure-mimic. Our findings support the expanded use of continuous electroencephalography in children with suspected encephalitis.