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Fetal Brian Development Part 1. 指導 洪正修主任 楊明智主任 陳志堯 2006.12.15. Anatomy. Head and neck. Cerebellum Choroid plexus Cisterna magna Lateral cerebral ventricles (Atrium) Midline falx Cavum septi pellucidi AIUM guideline. Embryologic Events. 3 rd ~4 th wk neural plate and folds appear
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Fetal Brian DevelopmentPart 1 指導 洪正修主任 楊明智主任 陳志堯 2006.12.15
Head and neck • Cerebellum • Choroid plexus • Cisterna magna • Lateral cerebral ventricles (Atrium) • Midline falx • Cavum septi pellucidi AIUM guideline
Embryologic Events • 3rd~4th wk neural plate and folds appear • 3 major divisions of brain • Prosencephalon (forebrain) • Mesencephalon (midbrain) • Rhombencephalon (hindbrain) • 5th week further division of 3 primary brain vesicles • After 5th Further differentiation
Five Cephalons 9+ wks Rhombencephalon Prosencephalon
Cerebral hemisphere • Choroid plexus • Internal capsule • Olfactory bulbs and tracts 5th wk Telencephalon Prosencephalon (forebrain) • Thalamus • Optic nerve • Geniculate & mamillary body • Pineal and pituitary glands Diencephalon Neural tube & folds 3~4th wk Mesencephalon (midbrain) Metencephalon Pons, cerebellum Rhombencephalon (hindbrain) Myelencephalon Medulla
Exencephaly, Anencephaly • Absence of cranial vault and varying amount of supratentorial brain. • Neural tissue wears away. • Neural tissue make D/D between Ex and An. • Mickey Mouse sign or Bart Simpsom appearance. • CRL less than expected.
Exencephaly, Anencephaly 續1 • 2nd and 3rd trimester: neural tissue dissolved. • Protuberant eyes. • Multi-factorial. • Risk Factor~ • Folic acid deficiency • Insulin-dependent diabetes • Hyperthermia • MTX, valporic acid, carbamazepine…(FA antagonist)
Exencephaly, Anencephaly 續2 • Epidemiology~ 1:1000 (UK) • M:F 1:4 • Associated anomalies: • Spinal bifida 27% • GU: 16% • Cleft lip/palate: 10% • GI: 6% • Cardiac: 4%
Agenesis of Corpus Callosum • ACC/Callosal dysgenesis • Ultrasound Findings~ • Mild ventriculomegaly • Colpocephaly (teardrop-shaped ventricle) • Prominent of interhemispheric fissure (IH cyst) • Elevation of 3rd ventricle • Absent of cavum septi pellucidi • Abnormal course of pericallosal artery • Other CNS anomalies: 50% • Lipomas (hyperechoic midline mass; 50% have ACC)
Agenesis of Corpus Callosum 續1 • Chromosomal anomalies in 10~20%: Trisomy 18,13, 8 • Teratogens: alcohol, cocaine, valproate • Infection: CMV & rubella • 0.3~0.7% of general population, M>F • Fetal body anomalies seen in 60%
Thanks for Attention! My son, give attention to my words; let your ear be turned to my sayings. Let them not go from your eyes; keep them deep in your heart. For they are life to him who gets them, and strength to all his flesh. And keep watch over your heart with all care; so you will have life. Proverb 4:20~23
小腦到幾週發育完成? • True BPD view 可以看到哪最重要之三個腦部結構? • Absence of corpus callosum在超音波底下典型的signs,試列出兩項。