1. To explore the clinical and radiological characteristics of Human Parechovirus-induced encephalitis in infants aged less than three months.

2. To assess the incidence of seizures and characterize brain imaging  findings among patients with Central Nervous System (CNS) involvement.

Human Parechovirus (HPeV) is increasingly recognized as a significant cause of viral meningoencephalitis in infants, with prevalence showing both seasonal and biennial peaks.  According to U.S. National enterovirus surveillance, prevalence has ostensibly risen from 2.1% to 4.5% in 2016. Data on neuroimaging and electrographic features of HPeV are sparse. Despite growing awareness of HPeV's clinical relevance, particularly in neurological involvement, existing research is limited. This study aims to offer a comprehensive description of clinical features and outcomes associated with HPeV-induced CNS manifestations in infants under three months.

A retrospective case study was conducted on infants under three months of age diagnosed with Human Parechovirus-induced encephalitis via CSF-PCR tests. Data were collated on demographics, clinical symptoms, laboratory findings, neuroimaging, and electroencephalographic outcomes. Descriptive statistical methods were employed for data analysis, following institutional review board approval.

The study comprised 12 cases, average age was 26 days. Fever and lethargy emerged as predominant symptoms. All subjects were admitted for hospital care. Of the three patients who underwent brain MRI, all demonstrated abnormal findings. Continuous EEG monitoring was conducted for four patients, revealing multifocal epileptiform discharges in each and seizures in three. No instance of CSF pleocytosis was observed. All patient were discharged from the hospital.

The study illuminates the clinical and radiological signatures of CNS involvement in Human Parechovirus infections in infants younger than three months. The findings underscore the need for heightened vigilance for potential seizure activity and the importance of early brain imaging in this vulnerable population, particularly when seizures are suspected.