Patterns of Complications of Neonatal and Infant Meningitis on MRI by Organism: a 10 Year Review

Introduction: Imaging of meningitis in neonates and infants is not routine, but is frequent for complications. Aside from tuberculosis and herpesvirus, imaging findings related to most responsible pathogens are thought to be nonspecific, but few studies exist. We reviewed the imaging features of complicated meningitis in infants and neonates at our hospital in the past decade, hypothesizing that patterns of complications might be more specific than previously recognized.

Methods: 10 yr retrospective review of magnetic resonance imaging (MRI) and microbiology data for all neonates (age <30 d) and infants (age <1 yr) imaged for possible complications of meningitis at a tertiary children's hospital.

Results: We had 63 patients (25 neonates, 38 infants). The 3 most common pathogens were streptococcal species (n=32, mean age 4.7 mo), E. coli (n=9, mean 1.2 mo), and herpes simplex virus (n=4). The most common findings were meningeal enhancement (78% of those given IV contrast), infarct (52%), subdural collection (35%), and ventriculomegaly (32%). E. coli presented much more frequently with ventriculomegaly (64% vs. 22%) than streptococcal species. Extensive infarcts were typical of streptococcal meningitis (13/32, 41%) and rarely seen with other organisms (2/31, 6%, p=0.001). All 3 cases of Serratia meningitis had large parenchymal abscesses, and 2/4 cases of meningococcus had occipital cortical necrosis.

Conclusion: Although overlap was present, each organism responsible for neonatal/infant meningitis produced an identifiable pattern of complications on MRI. Recognising these patterns can help the radiologist suggest possible diagnosis and influence early management.