Cerebellar subpial hemorrhage - an underestimated location of fetal intracranial hemorrhage.

Abstract

Background and purpose: Subpial hemorrhage (SPH) is a rare form of intracranial hemorrhage, typically observed in neonates. It differs from subarachnoid and subdural hemorrhages in both anatomical location and underlying pathophysiology. The primary aim of this study was to describe the distinct fetal MRI features of cerebellar SPH.

Methods and materials: This retrospective multi-center study included twenty-four fetuses, aged between 20+5 and 34+0 weeks of gestation, from three institutions. Postmortem 3T MRI and neuropathological workup were available for four cases and one post-natal MRI.

Results: SPH was located infratentorially along the cerebellum and vermis in all 24 cases. SPH was observed as either unilateral, bilateral, or multifocal, with several distinct morphological patterns, crescentic or spherical/punctate shapes along the cerebellar surface. Postmortem MRI in one case confirmed the prenatal MRI findings, and neuropathological analysis confirmed SPH extending from the pia-arachnoid through the molecular layer, and hemosiderin-containing macrophages within the external granular layer associated with reduced and disrupted Bergmann glial processes in areas adjacent to SPH.

Conclusion: Fetal cerebellar SPH are characterized by crescentic foci of signal abnormality that appear "attached" to the cerebellar surface. Cerebellar SPH constitutes a distinct entity that may be detected on prenatal imaging, either in isolation or in association with fetal germinal matrix-intraventricular hemorrhage (GM-IVH).

Abbreviations: SPH = Subpial hemorrhage, US = Ultrasound, GM-IVH = Germinal matrix -Intraventricular hemorrhage, IVH = Intraventricular hemorrhage, DWM = Dandy Walker malformation, FGR = Fetal growth restriction, TTTS = Twin-Twin Transfusion Syndrome, SSFSE = Single-shot fast spin-echo, EGL = External granule layer.