Preterm cerebellum at term age: ultrasound measurements are not different from infants born at term.

Background: Reduced supratentorial brain growth has been shown in preterm-born infants at term-equivalent age (TEA), but cerebellar growth may be preserved in the absence of supratentorial injury. Our study aims to compare cerebellar size assessed using cerebral ultrasound (cUS) at TEA between preterm infants and term-born controls.

Methods: Cerebellar dimensions (including transverse cerebellar diameter (TCD), cerebellar vermis height, anteroposterior vermis diameter (APVD), and cerebellar vermis area (CVA)) were measured using Image Arena software (TomTec Imaging Systems, Unterschleissheim, Germany) in 71 infants <32-wk gestation without significant scan abnormality at TEA and in 58 term-born control infants. Intra- and interobserver agreement were evaluated.

Results: In comparison with controls, preterms at TEA had smaller TCDs (4.9 vs. 5.2 cm; P < 0.001) but larger CVAs (4.7 vs. 4.3 cm(2); P < 0.005) and APVDs (2.4 vs. 2.2 cm; P < 0.001); however, these differences were no longer seen after accounting for head shape. In <28-wk gestational age infants, CVA was statistically similar to controls, as were for small-for-gestational-age infants.

Conclusion: Our data support neonatal sparing of preterm cerebellar growth that is measureable using cUS, and this includes the most immature and small-for-gestational-age infants. We suggest cUS can be used to assess cerebellar size at TEA, with measures of both width and height being taken into account, and thus may be a useful tool for detecting infants with poorer cerebellar growth who are at increased risk of disability.