Neuropediatrics 2013; 44 - A16
DOI: 10.1055/s-0033-1347349

Posterior fossa abnormalities in high-risk term infants: Comparison of ultrasound and MRI

S Steggerda 1, F de Bruïne 2, V Smits-Wintjens 1, P Verbon 1, F Walther 1, G van Wezel-Meijler 3
  • 1Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
  • 2Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
  • 3Department of Neonatology, Isala Hospitals, Zwolle, The Netherlands

Background: On routine cranial ultrasonography (CUS) through the anterior fontanelle (AF), visualization of the posterior fossa (PF) is limited. The mastoid fontanelle (MF) improves detection of PF abnormalities. The objective of this study was to investigate the characteristics of PF abnormalities in high-risk full term infants, using MF-CUS in addition to AF-CUS, and to compare CUS with magnetic resonance imaging (MRI).

Patients and Methods: A database search identified all term infants (≥36 weeks) born between 2008 and 2012 admitted to our level 3 neonatal intensive care unit with hypoxic-ischemic encephalopathy (HIE), central nervous system infection, intracranial hemorrhage, stroke, metabolic disorder, and/or congenital malformation. A total of 108 infants, studied with MF-CUS and MRI, were included. We calculated predictive values of MF-CUS for PF abnormalities on MRI.

Results: PF abnormalities were diagnosed on MF-CUS in 42/108 infants. MRI confirmed the CUS findings in 40 and showed additional abnormalities in 30 infants. Sensitivity and specificity of MF-CUS were 65% and 99% for cerebellar abnormalities, 43% and 98% for other PF abnormalities, and 94% and 100% for abnormalities in/around the fourth ventricle, respectively. Especially small subdural hemorrhage (n= 21), punctate cerebellar hemorrhage (n= 7) and diffusion restriction within the cerebellar vermis in HIE (n= 3) were missed by MF-CUS. In most cases, AF views were insufficient to diagnose PF abnormalities.

Conclusion: In term infants MF-CUS can demonstrate PF abnormalities that are missed with AF-CUS. Punctate cerebellar hemorrhages and involvement of the vermis in HIE may remain undetected even when the MF approach is used. The prognostic implications of these lesions need further investigation.