Ultrasound Measurements of Intracranial Structures in Growth-Restricted Neonates with Fetal Blood Flow Redistribution: A Pilot Observational Study

Abstract

<b><i>Background:</i></b> Fetal growth restriction (FGR) is associated with neonatal and long-term neuro-morbidity. Preferential redistribution of blood flow to the brain is a common antenatal adaptation in FGR. The impact of this “brain sparing,” which may signify severity of FGR, on the growth of brain structures has not been studied. <b><i>Aim:</i></b> To compare corpus callosum (CC), cerebellar, and ventricular measurements of FGR neonates with evidence of fetal blood flow redistribution with those of gestation-matched appropriately grown (AGA) neonates. <b><i>Methods:</i></b> This was a pilot, prospective observational study conducted at a tertiary level neonatal unit in Melbourne, Australia. Cranial ultrasound was done between days 1 and 3 of life in FGR and AGA neonates. <b><i>Results:</i></b> Cranial ultrasound on 20 FGR, gestation (mean ± SD) 31.4 ± 3.1 weeks, weight 1,205 ± 463 g, and 20 AGA neonates, 31.1 ± 3.0 weeks, 1,668 ± 490 g, was performed. CC length was significantly decreased in FGR neonates as compared to AGA neonates (35.28 ± 3.47 vs. 38.83 ± 4.05 mm, <i>p</i> = 0.0002). CC was significantly thinner at genu (3.36 ± 0.66 vs. 4.04 ± 0.83 mm, <i>p</i> = 0.007), body (1.97 ± 0.36 vs. 2.27 ± 0.39 mm, <i>p</i> = 0.02), and splenium (4.07 ± 0.76 vs. 4.72 ± 0.75 mm, <i>p</i> = 0.003) in FGR vs. AGA neonates. CC-fastigium length was also significantly decreased (39.65 ± 3.87 vs. 41.96 ± 4.50 mm, <i>p</i> = 0.04). Similarly, FGR neonates showed decreased transverse cerebellar diameter (36.15 ± 5.51 vs. 38.81 ± 7.21 mm, <i>p</i> = 0.02), but ventricular measurements were comparable. In multivariate analysis, these differences were evident independent of the birth weight. <b><i>Conclusions:</i></b>CC and cerebellar measurements are significantly smaller in FGR neonates with fetal blood flow redistribution, which warrants further study.

Neurosonographic assessments of corpus callosum related structures in growth‐restricted fetuses

“…When placental dysfunction continues, intrauterine stress and hypoxemia get prolonged and severe, cerebral perfusion shifts to brain structures that is fed by the middle cerebral artery. 2 The decreased resistance 13 In a study by Koning et al, shorter CCL and CCLF were observed in FGR and these measurements might have been important in the neurodevelopmental status of infants born with FGR. 16 However, due to the lack of information related to the umbilical cord blood samples in the present study, the authors could not confirm intrauterine hypoxia.…”

“…12 Previous studies using fetal magnetic resonance imaging and ultrasonographic scanning have detected a smaller CC in preterm and/or growth-restricted fetuses. 13,14 Fastigium can be defined as a thin roof plate of the fourth ventricle and one the crucial marker of the normal posterior fossa development. 15 Koning et al, also demonstrated that fetuses with FGR and neonates born with FGR were associated with decreased growth of CC-fastigium length (CCFL), which is a valuable marker of diencephalon and mesencephalon development.…”

“…Several neurosonogram-based studies have demon-Not only white matter structures but also the gray matter may be affected by intrauterine hypoxia and the intrauterine conditions leading to hypoxia as in FGR. Previous studies have stated the measurement of CCF as a sonographic marker of diencephalon development 13,15,16. Pharande et al, reported that shorter CCL and CCFL, thinner CC at genu, body and splenium were detected in growth-restricted fetuses.…”

Changes in structural brain development after selective fetal growth restriction in monochorionic twins

“…Our results are similar to those of a pilot study on cUS measurements in singletons, reporting that FGR neonates with antenatal brain sparing have a smaller corpus callosum and cerebellum 4 . In our study, no additional effect of brain sparing was found.…”

“…The hemodynamic adaptation of the brain to suboptimal growth conditions can be detected antenatally as ‘brain sparing’, a redistribution of blood flow to the brain indicated by a decreased cerebroplacental ratio (CPR) 3 . Despite this supposedly protective mechanism, deficits in brain structures are prevalent in FGR singletons, and include reduced intracranial volume, corpus callosal size and cerebellar diameter 4 , 5 . These structural deficits are known to have significant consequences for brain function in childhood, being associated with, for example, lower cognitive test scores and impaired motor skills 6 .…”