Characteristic MR Imaging Findings of the Neonatal Brain in RASopathies

Neuroimaging features in neonates with RASopathies are rarely reported, and to date, there are no neuroimaging studies conducted in this population. Our aim was to investigate the occurrence of supratentorial and posterior fossa abnormalities on brain MRIs of neonates with a RASopathy.

An observational case-control study of neonates with a confirmed RASopathy was conducted. The presence of an intraventricular and/or parenchymal hemorrhage and punctate white matter lesions and assessments of the splenium of the corpus callosum, gyrification of the cortical gray matter, and enlargement of the extracerebral space were noted. The vermis height, transverse cerebellar diameter, cranial base angle, tentorial angle, and infratentorial angle were measured.

We reviewed 48 brain MR studies performed at 3 academic centers in 3 countries between 2009 and 2017. Sixteen of these infants had a genetically confirmed RASopathy (group 1), and 32 healthy infants were enrolled as the control group (group 2). An increased rate of white matter lesions, extracerebral space enlargement, simplification of the cortical gyrification, and white matter abnormalities were seen in group 1 (P < .001, for each). The vermis height of patients was significantly lower, and tentorial and infratentorial angles were significantly higher in group 1 (P = .01, P < .001, and P = .001, respectively).

Neonates with a RASopathy had characteristic structural and acquired abnormalities in the cortical gray matter, white matter, corpus callosum, cerebellum, and posterior fossa. This study provides novel neuroimaging findings on supratentorial and posterior fossa abnormalities in neonates with a RASopathy.