Dandy Walker Syndrome

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Dandy Walker Syndrome

Text of Dandy Walker Syndrome

  • 1. Fetal Brain AnomaliesPart II 2007.1.19

2. Dandy-Walker continuum Holoprosencephaly Chiari II malformation 3. Dandy-Walker Malformation Dandy-Walker continuum Dandy-Walker complex Dandy-Walker spectrum 4. History In 1914, Blackfan and Dandy described somealterations of the posterior fossa as (a)cysticdilatation of the fourth ventricle, (b)hypoplasia ofthe cerebellar vermis, (c)separation of thecerebellar hemispheres, (d)dilatation of themesencephalic aqueduct and (e)absence of themediate and lateral apertures of the fourthventricle. TThheessee aabbnnoorrmmaalliittiieess wweerree rreeffeerrrreedd ttoo aass DDaannddyy--WWaallkkeerrmmaallffoorrmmaattiioonn.. IInn tthhee 11997700 aanndd 8800 ddiiffffeerreenntt ddeeffiinniittiioonnsswweerree iinnttrroodduucceedd ffoorr ssiimmiillaarr aabbnnoorrmmaalliittiieess ooff ppoosstteerriioorrffoossssaa aanndd tthheenn tthhee ccllaassssiicc ddeeffiinniittiioonn ooff tthhee DDaannddyy--WWaallkkeerr mmaallffoorrmmaattiioonn.. 5. Classification Dandy-Walker malformation: increaseof the posterior fossa, complete orpartially agenesis of the cerebellarvermis, and a tentorium elevation. 6. Variant of Dandy-Walker: hypoplasiaof the cerebellar vermis in differentdegrees with or without increase ofthe posterior fossa. 7. Mega-cisterna magna: increase ofthe cisterna magna with integrity ofthe cerebellar vermis and fourthventricle. 8. Image Findings Large posterior fossa with big CSF cyst. 4th ventricle appears open and contiguouswith PF cyst. Vermis severely hypoplastic or absent. 9. AAssssoocciiaatteedd FFiinnddiinnggss CNSVentriculomegalyDysgenesis of corpus callosumHoloprosencephalyEncephaloceles, cephalocelesNTD Extra-cranialCleft lip/palateCardiac defectsPolycystic kidneys 10. Genetics The chromosomal abnormalities includetrisomies 18, 13, 21 and Turner syndrome. 11. Differential Diagnosis Mega Cisterna Magna Arachnoid Cyst (AC) Dandy-Walker Variant Persistent Blake Pouch Cyst Congenital Vermian Hypoplasia 12. Environmental Factor &Epidemiology Maternal diabetes. Alcohol. Early in utero infection. 1:25000~1:35000 live birth. 10% of infantile hydrocephalus. 13. Natural History &Prognostic TThhee ccllaassssiicc mmaallffoorrmmaattiioonn iiss uussuuaallllyy cclliinniiccaallllyy mmaanniiffeesstt iinntthhee ffiirrsstt yyeeaarr ooff lliiffee wwiitthh ssyymmppttoommss ooff hhyyddrroocceepphhaallyy aanndd//oorrnneeuurroollooggiiccaall ssyymmppttoommss.. TThhee mmoorrttaalliittyy iiss 2244~~4400%% bbuutt wwiitthhccuurrrreenntt nneeuurroossuurrggiiccaall tteecchhnniiqquueess mmoorrttaalliittyy hhaass bbeeeennddeeccrreeaassiinngg.. TThhee iinntteelllleeccttuuaall ddeevveellooppmmeenntt iinn tthhee ssuurrvviivvoorrss iissccoonnttrroovveerrssiiaall.. IInntteelllleeccttuuaall ddeeffiicciitt mmaayy bbee iinn tthhee rraannggee ooff4400 ttoo 7700%% ooff tthhee ccaasseess.. IIQQ:: 3355~~5500%% nnoorrmmaall.. TThhee iissoollaatteedd ddeeffeecctt sseeeemmss ttoo bbee aassssoocciiaatteedd wwiitthh bbeetttteerrpprrooggnnoossttiicc.. 14. Management There is no modification of standardobstetric management. All fetuses should be karyotyped. Cesarean delivery is indicated only ifmacrocrania is present. 15. Dandy-Walker continuum Chiari II malformationHoloprosencephaly 16. Abbreviations and Synonyms Chiari II Arnold Chiari II Spinal bifida Open neural tube defect (ONTD) 17. History The Arnold-Chiari was first identified in1883 by Cleland. It is characterized by theprolepses of hindbrain structures below thelevel of the foramen magnum. It can beassociated with skeletal abnormalities andneurological dysfunction. The nickname banana sign has beenapplied to the deformity of the cerebellum. 18. Definitions Symptomatic hindbrain herniationCerebellar vermis herniate through foramenmagnum4th ventricle displayed inside neural canalTentorium pulled downwardMedulla displaced inferiorly and kinked Virtually 100% associated with ONTD 19. Three Types of Arnold Chiari Type I: just a lip of cerebellum is downwardly displacedwith the tonsils, but the fourth ventricle remains in theposterior fossa. This is mainly an incidental CTdiscovery. Type II: usually involved in prenatal cases and is acongenital deformity characterized by displacement ofcerebellar tonsils, parts of the cerebellum, fourthventricle, pons, and medulla oblongata through theforamen magnum into the spinal canal. Type III: more severe form, with large herniation of theposterior fossa content and myelomeningocele andhydrocephalus 20. Imaging Findings Posterior fossa banana signCisterna magna obliteration (most common)CM is small or gone (10mm) ONTD (open NTD spinal bifida) 73% lumbar 17% sacral 9% thoracic 1% cervical 21. Special Concerns ONTDBony dorsal arch defect + neural contentexposureU shaped vertebra on axial view Meningocele sac Myelomeningocele Associated findings24% (1/4) clubfoot40% fetus with additional anomalies (67%aneuploid fetuses with other anomalies)Scoliosis & kyphosis 22. Differential Diagnosis Sacrococcygeal teratoma Aqueductal stenosis Moderate to severe hydrocephalus atria > 15mm & dangling choroid plexus DWC Isolated frontal bone concavity Seen in 1% of normal fetuses 3rd trimester resolve Normal CM 23. Genetics & Epidemiology 4% aneuploid rate with spinal bifida Trisomies 13, 18 0.41000 3% of all spontaneous abortion 1~2 % recurrent rate 24. Clinical Issues Most commonmaternal AFP Nature history & prognosis High morbidity and mortality (35% 5yrs) 50% IQ>80 Intrauterine findings outcomeObstructive hydrocephalus Musculoskeletal dysfunction (25% lower ext)GI or GU dysfunction 25. Treatment Cesarean section Immediate post-natal ONTD surgery In utero surgery in clinical trial Preventive treatment with folic acid 4mg/day reduces recurrence by 70% 26. Dandy-Walker continuum Chiari II malformation Holoprosencephaly 27. Psalms chapter 115 13~16HHee wwiillll bblleessss tthheemm tthhaatt ffeeaarr tthhee LLOORRDD,,bbootthh ssmmaallll aanndd ggrreeaatt.. TThhee LLOORRDD sshhaalllliinnccrreeaassee yyoouu mmoorree aanndd mmoorree,, yyoouu aannddyyoouurr cchhiillddrreenn.. YYee aarree bblleesssseedd ooff tthheeLLOORRDD wwhhiicchh mmaaddee hheeaavveenn aanndd eeaarrtthh..TThhee hheeaavveenn,, eevveenn tthhee hheeaavveennss,, aarree tthheeLLOORRDD''ss:: bbuutt tthhee eeaarrtthh hhaatthh hhee ggiivveenn ttootthhee cchhiillddrreenn ooff mmeenn.. 28. QUIZ TIME 29. Dandy-Walker Continuum A. Turner syndromeB. Trisomy 18C. Trisomy 21D. Trisomy 13 30. DWC & Chiari IIA. vermisDWCvermisabsent or severelyhypoplasticB. DWCtentoriumelevatedChiari IIdownward displacementC. DWC100%ONTDspinal bifida 31. Chiari IIA. Banana signB. Lemon head signC. Severe hydrocephalusD. 100% ONTD