Tamara Feygin, Robert A. Zimmerman, Cerebral medullary veins: normal and abnormal pattern in fetal and pediatric patients. Tamara Feygin, Robert A. Zimmerman, Larissa T. Bilaniuk, Monica Epelman, Erin Simon- Schwartz, Avrum N. Pollock imaging appearance of normal anatomy and pathologic pattern of cerebral medullary veins in fetuses and in kids. 1

Cerebral medullary veins Fetal US Fetal MRI Neonatal MRI With modern equipment more and more often seen in fetal and postnatal brain MRIs and US and sometimes it’s difficult to decide if they are pathologic or not and what its their significance

Cerebral Medullary Veins Recent increased interest in imaging of medullary veins. New classification of unilateral periventricular infarction is based on precise anatomy of the affected vessels “Venous subtypes of preterm periventricular haemorrhagic infarction” by J. Dudnink et al,2007. Arch Dis Child Fetal Neonatal Ed 2008;93:F201-F206 doi:10.1136/adc.2007.118067 The importance of familiarity with medullary veins anatomy was shown in excellent paper on subtypes of venous infarctions published in 2007 by Dudnink et al 3

Purpose: To characterize imaging features of normal and abnormal medullary veins. To define their role in the pathogenesis of certain cerebral disorders in fetal and pediatric brains So, we present our work with purpose to … 4

Normal supratentorial medullary veins Superficial medullary veins: short channels in WM, drain to the cortical surface, variable in number and location Deep medullary veins: longer channels, drain toward the ventricles, much less variation Transcerebral (anastamotic) veins are divided on 3 groups: 1st- vast variability in morphology. 2d group is our interest

Deep Medullary Veins ~ 2000-4000 very small (0.05-0.35 mm in caliber) veins drain periventricular WM and GM 1936 First histological report of fan-shaped pattern of medullary veins thrombosis (H.Ehlers,et al) 1986 Periventricular architecture is demonstrated by microvenography (S.Takashima,et al) Run perpendicular to the long axis of the lateral ventricles on sagittal and converge on the corners of lat vent in a fan-shaped pattern Pathology reports on medullary veins abnormality precede imaging because of such a small size of these vessels; Normally M.V. are not seen on conventional imaging. First demonstration by Takashima group

Deep Medullary Veins Pattern is not random Strongly related to embryonic path of neurons migration Unique arrangement and anatomic details may lead to predisposition for thrombosis Seemingly provide vascularization of actively proliferating neuroepitelium and support a pathway along with glia to neurons to their cortical destination

Deep Medullary Veins When engorged appear in a spectrum of pathologies Normally seen in fetal brains from 18 to 32 wks Not seen on conventional cross- sectional imaging or conventional angiogram, but may appear on SWI In normal fetal and postnatal brains MV are fine, linear structures, extending from outer wall of the lat. Vent. They are rather symmetric, although some asymmetry may present. When MV are seen on conventional sequences it strongly suggests serious abnormality of venous drainage, causing pathologic engorgement/thrombosis. Fetal EPI T2WI

Abnormal patterns Apparent on conventional T1, T2,post contrast MRI, US Primary pathology of medullary veins such as thrombosis or septic thrombophlebitis Compensatory proliferation/engorgement (elevated intracerebral venous pressure, tumoral neovascularity, etc)

Abnormal patterns: Thrombosis of medullary veins Periventricular hemorrhagic venous infarction (PVHVI) in the setting of prematurity and germinal matrix hemorrhage. Hemorrhagic periventricular leukomalacia (PVL) Perinatal venous infarction of uncertain etiology with Wallerian degeneration Diffuse hypoxic-ischemic injury to deep cerebral WM

Ex 29 wks, 3 day old boy Periventricular hemorrhagic venous infarction in the setting of prematurity and germinal matrix hemorrhage/IVH. T2WI

Ex-premature at 31 wks 11 day old Periventricular hemorrhagic venous infarction MRI, T2WI Sagittal US It is important to differentiate GM-IVH from bilateral hemorrhagic PVL.These two entities are distinct in their neurodevelopmental outcome, which is more favorable for the GM-IVH 12

FT with severe CHD (Ebstein anomaly), hemorrhagic PVL Sagittal T1 Coronal T2 Axial GRE

Abnormal patterns: Septic thrombophlebitis One of the key factors in pathogenesis of cerebral neonatal abscess Confined to cerebral medullary veins Occurs in the setting of neonatal meningitis caused by Gram negative microbes, such as Citrobacter species and Serratia Marcescens Complicated by deep WM abscesses

Neonatal abscesses, Citrobacter meningitis 3wks old, with sz and fever T2WI DWI Post GD GRE

Serratia Marcescens meningitis GRE Post Gd T2WI 16

Abnormal patterns (engorgement): Primary pathology of dural venous sinuses Abnormal proliferation of medullary veins caused by elevated cerebral venous pressure (dural venous thrombosis) Vein of Galen malformation Dural AV fistula Some superficial arterio-venous malformations

Superficial Arteriovenous Malformation T1WI, 3 Tesla

20wks fetus with numerous anomalies delivered by EXIT procedure at 31 wks of GA. The extend of airway agenesis was inoperable and the fetus expired 17 min post-delivery 19

Conclusion: Deep medullary veins are the smallest cerebral vessels, which can be recognized on MRI, US(linear probe) and conventional angiography. These veins can be viewed as an important site for cascade of pathologic events in fetal/pediatric brain. Early detection of abnormal appearance of medullary veins leads to more prompt diagnosis of serious cerebral injury.

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