Brain Bioelectrical Activity in Children with Acute Viral Encephalitis

The aim of the present work was to evaluate changes in brain bioelectrical activity using electroencephalography (EEG) data in children with acute viral encephalitis. A total of 26 children were studied at the Pediatric Scientific Clinical Center for Infectious Diseases, Russian Federal Medical Biological Agency, with clinically confirmed diagnoses of “viral encephalitis.” Boys dominated the sex ratio of 18:8; mean age was 12 ± 2.1 years. All patients were in the acute period (first 14 days). The reference group for EEG analysis consisted of 10 healthy children. The groups were uniform in terms of sex and age. EEG recordings were made in all patients using a Neuron Spectrum 3 encephalograph (Ivanovo, Russia), with visual analysis of the EEG and spectral frequency analysis. Spectral power was evaluated in the α, θ, and δ frequency ranges, and the α/θ, α/δ ratios were also determined. Visual analysis of the EEG showed that 100% of children in the acute period of viral encephalitis showed diffuse slowing with recording of δ and θ frequencies. Focal changes in the form of sharp waves were recorded in 85% of cases (21 patients). Periodic activity was not recorded in even a single case in the study group of patients. Quantitative analysis of the results of statistical processing identified statistically significant decreases in the α/θ ratio (p = 0.035), maximum α (p = 0.046) and minimum θ (p = 0.044) in encephalitis patients as compared with the healthy children group. These data lead to the conclusion that pediatric patients during the acute period of viral encephalitis show significant impairments to the normal α/θ EEG power ratio. This impairment was apparent as a reduction in the power of the α and θ rhythms. It can be suggested that the cause of this reduction is suppression of the functional activity of the thalamus and thalamocortical pathways, as well as the reticular formation of the brain.