Cerebellar hemorrhage in neonates: pattern analysis by ultrasonography and magnetic resonance imaging

BackgroundCerebellar hemorrhage in neonates is increasingly being identified but is still underdiagnosed. While magnetic resonance imaging (MRI) is the optimal imaging modality for cerebellar hemorrhage evaluation, ultrasonography (US) is commonly used for screening. Characterizing the patterns and distribution of cerebellar hemorrhage lesions can help facilitate its detection by aiding to focus on prevailing type of cerebellar hemorrhage.ObjectiveThis study aimed to analyze the patterns of cerebellar hemorrhage in neonates, comparing US findings with MRI.Materials and methodsThis was a retrospective study of 765 neonatal intensive care unit (NICU)-admitted neonates who underwent brain MRI due to various clinical and radiological requirements. Two pediatric radiologists reviewed brain MRI and US in consensus, and cerebellar hemorrhage patterns were classified based on MRI findings: type 1, punctate cerebellar hemorrhage without cerebellar volume loss; type 2, focal cerebellar hemorrhage with cerebellar volume loss; type 3, ovoid/crescent cerebellar hemorrhage in the periphery of the cerebellar hemisphere; type 4, isolated vermian cerebellar hemorrhage; type 5, cerebellar hemorrhage involving almost the entire cerebellar hemisphere. The distribution and US detection rates of cerebellar hemorrhage were compared according to the cerebellar hemorrhage type.ResultsA total of 56 (33 male, 23 female) cases (7.32%) among 765 MRIs showed cerebellar hemorrhage (median gestational age, 27 + 1 weeks [IQR 5 + 2]; median birth weight, 955 g [IQR 882.5]). The most common pattern was type 1 (60.7%). Type 3 cerebellar hemorrhage was more commonly observed in the inferior and peripheral cerebellum compared to types 1 and 2 cerebellar hemorrhage (P=0.002). In retrospective review of images, type 3 was the most commonly missed type of cerebellar hemorrhage (initial US detection rate, 33.3%; retrospective US detection rate, 75%).ConclusionThis study underscores the importance of understanding cerebellar hemorrhage patterns and suggests that careful inspection of inferior and periphery of the cerebellum is important to avoid missed diagnosis of cerebellar hemorrhage.