Chapter 8 - Electroencephalography in Children With Acute Encephalitis/Encephalopathy

Abstract

Electroencephalography (EEG) is considered to be useful for diagnosis and prognostication in children with acute encephalitis/encephalopathy (AE). Several EEG abnormalities have been reported in children with AE. Generalized, unilateral, or focal slowing is frequently observed in children with AE. Low voltage is seen in severely affected children. Increase in fast activities is characteristic in anti-NMDA receptor encephalitis, whereas decrease in fast activities is sometimes seen in children with acute encephalopathy with biphasic seizures and late reduced diffusion. Although periodic discharges, paroxysmal discharges, and episodic transients have been reported in various types of AE, they are considered to be nonspecific findings. Ictal changes can be observed in some children with AE, especially in those with acute encephalitis with refractory, repetitive partial seizures and hemorrhagic shock and encephalopathy syndrome. Continuous EEG monitoring has recently been applied to critically ill children with impaired consciousness. Electrographic seizures or electrographic status epilepticus is not infrequent in such children and can be overlooked without continuous EEG monitoring. Several studies have revealed that seizure burden and abnormal background activities may be related to mortality and poor neurologic outcome. Continuous EEG monitoring is considered to alter clinical management in seriously ill children. However, resource requirements are a limitation of continuous EEG monitoring. Quantitative EEG such as amplitude-integrated EEG has also been applied to seriously ill children with impaired consciousness. The main advantage of quantitative EEG is easy application and interpretation of EEG activities. Therefore, monitoring with quantitative EEG may be used as a surrogate for continuous EEG monitoring, although several limitations are present. Evidence of usefulness of EEG is still insufficient. The diagnostic and prognostic value of EEG should be confirmed by prospective multicenter studies in near future.