Original ArticleThe Role of Continuous Electroencephalography in Childhood Encephalitis
Introduction
Encephalitis occurs in 3.5-7.4 cases per 100,000 person-years in the general population with an incidence up to 16 times higher in children.1 In the National Hospital Discharge Survey between 1988 and1997, encephalitis accounted for 230,000 hospital days and 1400 hospital deaths annually.2 Children with encephalitis have diverse clinical presentations, with variable signs and symptoms including headache, meningismus, fever, changes in mental status such as lethargy or hallucinations, seizures, abnormal movements, or tremor, and focal neurological signs.1, 3 Children with symptoms consistent with encephalitis undergo medical management with a great deal of ambiguity as to their etiologic diagnosis, and most will never have a verifiable etiology for their illness.4 The California Encephalitis Project (CEP) was an attempt to identify etiologic agents and characterize the clinical course of patients with encephalitis; summaries of the infectious agents found and patient outcomes have been reported previously.3, 5, 6
Seizures, both clinical and subclinical, are common in children with encephalitis. Glaser et al.5 reported seizures in 42% of children in the CEP. Misra and Kalita7 reported that 37% of adults and 61% of children with encephalitis in a prospective hospital-based study had seizures. Dubray et al.6 reported that 62% of children with encephalitis had seizures, and that seizures were correlated with a prolonged illness and worse outcome. However, seizures can be difficult to recognize in patients with encephalitis and it is unclear whether routine electroencephalograph (EEG) is sufficient to rule out seizures in this population; in a study of intensive care unit (ICU) patients (adults and children) with suspected central nervous system infection receiving continuous EEG monitoring (cEEG), 33% had a seizure while on the monitor and 64% of those seizures had no clinical correlate.8 Several recent reports of children receiving ICU monitoring in pediatric ICUs show that critically ill children frequency have seizures, seizures are frequency subclinical, and seizures are correlated with poor outcomes.9, 10, 11, 12, 13, 14, 15
In this study, we report EEG and clinical findings from all children who presented to Rady Children's Hospital of San Diego (RCHSD) between 2004 and 2011 and had diagnostic samples sent to the CEP. Our findings suggest that cEEG is important in the diagnosis and management of children with symptoms consist with encephalitis.
Section snippets
Study participants
Between 2004 and 2011, 222 children at RCHSD had diagnostic samples sent to the CEP. To be included in the CEP, children had to be hospitalized with encephalopathy lasting at least 24 hours and meet at least one of the following criteria: fever, seizure, focal neurological signs, pleocytosis, or EEG or neuroimaging evidence concerning to the treating clinicians for encephalitis.5 At the discretion of treating physicians, children who met these criteria had a standardized panel of blood,
Clinical presentation
The most common initial symptoms were fever (25.8%), headache (24.4%), altered sensorium (9.7%), seizure (9.2%), pain (such abdominal, back, eye, or limb pain; 6.0%), or symptoms of an upper respiratory tract infection (5.5%). Forty-four patients (20.3%) presented via emergency management services, whereas the rest were brought to medical attention by family members. Most patients (193, or 88.9%) presented through our emergency room, whereas the rest were transferred from another facility
Discussion
In this study, we presented data from a prospectively identified cohort of children with symptoms consistent with encephalitis who presented to our institution between 2004 and 2011 and had standardized testing for an infectious agent performed through the CEP. This study focused on our experience with EEG, specifically cEEG, in this cohort. We report that (1) when used, cEEG recorded a seizure in more than half of patients; (2) cEEG was more likely to record a seizure than routine EEG; (3) in
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