Human Parechovirus Meningoencephalitis: Neuroimaging in the Era of Polymerase Chain Reaction-Based Testing

Abstract

Human parechovirus infection is an increasingly recognized cause of neonatal meningoencephalitis. We describe characteristic clinical features and brain MR imaging abnormalities of human parechovirus meningoencephalitis in 6 infants. When corroborated by increasingly available polymerase chain reaction-based testing of the CSF, the distinctive MR imaging appearance may yield a specific diagnosis that obviates costly and time-consuming further clinical evaluation. In our study, infants with human parechovirus presented in the first 35 days of life with seizures, irritability, and sepsis. MR imaging consistently demonstrated low diffusivity within the thalami, corpus callosum, and subcortical white matter with a frontoparietal predominance. T1 and T2 shortening connoting white matter injury along the deep medullary veins suggests venous ischemia as an alternative potential pathogenetic mechanism to direct neuroaxonal injury.

Fig 1.

Axial diffusion-weighted images in patients 1–6 (infants with HPeV infection) demonstrate low diffusivity variably involving the periventricular white matter with frontoparietal predominance and also involving the corpus callosum, thalami, and internal and external capsules. Patients 3 and 4 exhibit greater involvement of the occipital white matter and the occipital cortex. Patient 5 shows more confluent involvement of the subcortical white matter.

Fig 2.

Axial 3D T1-weighted MPRAGE images (upper row) and axial T2-weighted images (lower row) in patients 1–6 (infants with HPeV infection) demonstrate foci of T1 and/or T2 shortening following the distribution of the deep medullary veins (arrows).

Fig 3.

Axial T2-weighted image (A) and sagittal T1-weighted image (B) obtained in patient 1 approximately 3 months after acute HPeV infection show new diffuse enlargement of the extra-axial spaces and thinning of the corpus callosum, suggesting volume loss.