1. Anomalies of the Posterior Fossa and the Spinal Cord- Fetal MRI Chen Hoffmann, MD Neuroradiology Sheba Medical Center, Israel Affiliated to Tel-Aviv University XIX SYMPOSIUM NEURORAGIOLOGICUM BOLOGNA OCTOBER 4-9, 2010

2. Indications Ventricular dilatation Ventricular asymmetry Malformations Disease found in siblings in previous pregnancies Vascular malformations Infectious diseases

3. Indications (cont’) US is the first imaging of choice When US is abnormal the MR is done to verify the diagnosis and to identify additional malformations US can be suboptimal (head position) Vermis is formed by 18 weeks GA

4. Anomalies of the Posterior Fossa Small PF (Chiari II) Cystic anomalies (Dandy-Walker, arachnoid cyst, mega cisterna magna) Others (rhombencephalosynapsis, Walker Warburg syn., vascular)

5. Myelomeningocele + Chiari II © Erin S. Schwartz, CHOP

6. Chiari II Small PF Downward herniation of cerebellum and brainstem Cervicomedullary kink 4 th ventricle elongated with no posterior point Open dysraphism (MMC) in 100%

7. 22w GA: Chiari II & Myelomeningocele on US Postnatal MRI: In Utero Repair © Orit Glenn, UCSF

8. Missed MMC 33 weeks GA Ventricular dilatation Partial agenesis of corpus callosum No associated anomalies known After birth- MMC! Only one image showed a cystic mass not in the midline

9. Additional Anomalies

10. Differential Diagnosis: Sacrococcygeal Teratoma

11. Differential Diagnosis: Currarino Syndrome

12. Suspected Chiari III

13. sagital axial Cranial Meningoencephalocele Post natal US

14. Cranial Meningoencephalocele Pre OP © Liat Ben Sira, TAMC

15. Cranial Meningoencephalocele Post OP MR Bone anomm.Diastemat.Post op PF

16. 22w GA: Lumbar spine bony anomaly on US © Orit Glenn, UCSF

17. Postnatal MRI at one day of age confirms findings of fetal MRI Dx: segmental spinal dysgenesis

18. Cystic Anomalies Dandy walker malformation Blake’s pouch Arachnoid cyst Mega cisterna magna

19. Dandy-Walker Complex Dandy-Walker Complex Dandy-Walker Complex Tentorium elevated Tentorium elevated Posterior fossa is enlarged Posterior fossa is enlarged Hypo genetic vermis and anti-clockwise rotated Hypo genetic vermis and anti-clockwise rotated Brainstem compressed Brainstem compressed

20. Dandy-Walker Complex The cerebellar hemispheres are dysplastic The 4 th ventricle is opened to the cisterna magna

21. Blake’s Pouch 22 weeks GA Large PF Lower part of the vermis is not formed Posterior part of the 4 th ventricle is open to the cisterna magna

22. Arachnoid Cyst A cystic lesion posterior to the cerebellum Vermis is intact A thin septum between the cyst and the cisterna magna

23. Others

24. Walker-Warburg Syn. Age of 1 week

25. Rombencephalosynapsis Fused cereballar hemispheres Absent vermis Absent primary fissure Narrow 4 th ventricle in Ax plane (key hole shape) +/- septo-optic dysplasia

26. 29w GA: Post. Fossa Mass on US, ? Subdural © Orit Glenn, UCSF

27. 31w GA: Follow-up MRI Dx: dural sinus malformation

28. Vein of Gallen Malformation A-V fistula between deep choroidal arteries and the median prosencephalic vein Of Markovski

29. The Chaim Sheba Medical Center Tel Hashomer, Israel Chen.hoffmann@sheba.health.gov.il