The Normal and Pathological Fetal Brain

Jean-Philippe Bault • Laurence Loeuillet

The Normal and Pathological Fetal Brain

Ultrasonographic Features Jean-Philippe Bault Laurence Loeuillet Centre d'échographie Ambroise Paré Hôpital Cochin Les Mureaux Paris France France

ISBN 978-3-319-19970-2 ISBN 978-3-319-19971-9 (eBook) DOI 10.1007/978-3-319-19971-9

Library of Congress Control Number: 2015947148

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Nothing could interest me more than this new Atlas of normal and pathological fetal brain ultrasound images prepared by Jean-Philippe Bault and Laurence Loeuillet with assistance from Guillaume Benoist. Its high-resolution images pro- vide not only a “map” of the developing brain but also close-ups of its various “territories.” In my younger days as a pediatrician and embryologist, focused on the problems of developmental anomalies, the fetal brain was terra incognita ! Prenatal brain imaging was in its infancy, and neuropathological examinations were conducted only rarely, for research purposes only. With guidance from Claudie Larroche, who was educated in neuropathology at Harvard, and inspired by her comprehensive knowledge of premature infants, we endeavored to undertake a systematic analysis of the fetal brain. Thousands of examinations later, we collated the results of this pioneering work on the dynamics of brain development and the signifi cance of its malformations – including a special focus on anatomical pathology-ultrasonic correlations – in what today have become a number of classic books: The Pathology of the Developing Human , S Duckett (ed) Lea & Febiger, 1994; Textbook of fetal and perinatal pathol- ogy , Vol. 2, Wigglesworth JS and Singer DB (eds), Blackwell Scientifi c Publications, Oxford 1995. Central Nervous System Malformations. Potter’s Pathology of the Fetus and Infant , Vol 2, Gilbert-Barness E (ed), Mosby, St Louis 1997, 2009. Because the fetal brain changes over time, its evaluation requires a comprehen- sive knowledge of brain development, which begins in the middle of the 3rd week of gestation and continues well after birth. The cerebral hemispheres and the cere- bellum emerge very rapidly at the end of the 4th week, while their synaptic connec- tions are slowly forged. The imaging of this origami-like art as practiced by nature requires patience and pertinence, akin to the special qualities of the great photogra- pher. The authors have met this challenge with talent! They have captured the dynamics of brain development every 2 weeks from the 8th to the 34th week of gestation. Each ultrasound image shown is accompanied by carefully selected pathology specimens and histology preparations, and this superimposition provides a clear picture of the architecture of the normal brain and of deformations in its shape and structure. Generous practical advice is given on how to acquire high- quality images and avoid pitfalls and, along with the precious guidelines provided, make this atlas immensely useful for those interested in the developing brain,

v vi Foreword particularly trainee sonographers and those who already have some experience and are seeking to perfect their technique. In vivo observation of the fetal brain is an ancient dream that has come true! The increasingly early acquisition of ever more high-resolution images has made ultra- sonography the tool of choice for the diagnosis of brain anomalies. After devoting the fi rst part of my life to a gross and microscopic analysis of the developing brain, I should now switch to evaluating its image, which is far more elegant.

Férechté Encha-Razavi, MD President of the Société Française de Foetopathologie , 2005–2009 Unité de Génétique Embryo-Foetale, Necker-Enfants-Malades, Paris Contents

Part I The Normal Brain

1 Brief Review of Embryology ...... 3 2 Ultrasound Images of the Normal Brain ...... 7 From 8 to 10 GW: Early Morphological Examination ...... 7 Anatomical Landmarks ...... 8 From 11 to 13 GW: Early Morphological Examination ...... 9 Anatomical Landmarks ...... 12 From 14 to 16 GW: Morphological Examination ...... 13 Anatomical Landmarks ...... 15 Anatomical Landmarks ...... 16 Anatomical Landmarks ...... 18 From 18 to 20 GW: Morphological Examination ...... 19 Anatomical Landmarks ...... 22 Anatomical Landmarks ...... 24 From 21 to 23 GW: Morphological Examination ...... 27 Anatomical Landmarks ...... 29 Midline ...... 29 From 24 to 26 GW: Morphological Examination ...... 41 Anatomical Landmarks ...... 45 Anatomical Landmarks ...... 48 From 28 to 30 GW: Morphological Examination ...... 48 Anatomical Landmarks ...... 53 Anatomical Landmarks ...... 56 From 32 to 34 GW: Morphological Examination ...... 57 Anatomical Landmarks ...... 62 3 Detailled Study of Certain Brain Structures ...... 63 Corpus Callosum ...... 63 Anatomy of the Corpus Callosum ...... 63 Development of the Corpus Callosum ...... 64 Ultrasonographic Features of the Corpus Callosum ...... 65

vii viii Contents

Lateral Ventricles ...... 73 Lateral Ventricles: Biometrics and Images ...... 73 Morphology ...... 76 Sylvian Fissure ...... 78 Sylvian Fissure and Study of the Gyration ...... 78 Sylvian Fissure ...... 78 Other Anatomical Landmarks ...... 88 Posterior Fossa ...... 91 Changes in the Cerebellum Over Time ...... 92 Normal Ultrasound Images of the Posterior Fossa ...... 97 Cerebral Circulation ...... 104 Pericallosal Circulation ...... 105 Arteries of Central Gray Nuclei ...... 110 Willis’ Circle ...... 111 Venous Circulation ...... 115 Sutures and Fontanels ...... 116 4 Brain Biometrics ...... 123 Biparietal Diameter (BPD) and Head Circumference (HC) ...... 123 Atrial Diameter ...... 125 Cisterna Magna ...... 125 Corpus Callosum ...... 126 Cerebellum and Brainstem ...... 127 Transverse Diameter ...... 127 Cerebellar Vermis and Brainstem ...... 128 Interorbital Distance ...... 130 5 Tips and Traps ...... 131 Choosing the Right Route of Approach ...... 131 Use of the Transvaginal Approach ...... 132 Moving the Fetus ...... 133 Use of 3D Ultrasound ...... 134

Part II The Pathological Brain

6 First-Trimester Pathologies ...... 137 Acrania ...... 137 ...... 141 Opacities in Images ...... 145 Brain Anomalies Related to Neural Tube Closure Anomalies ...... 148 Anomalies of the Posterior Fossa ...... 151 7 Second- and Third-Trimester Pathologies ...... 153 Skull Contour Anomalies ...... 153 Acrania ...... 153 Opacities in Skull Images ...... 154 Other Examples of Skull Deformations Related to Craniosynostosis . . 161 Contents ix

Midline Anomalies ...... 163 Holoprosencephaly ...... 163 Corpus Callosum Anomalies ...... 167 Ventriculomegaly ...... 181 Defi nitions ...... 181 Etiologies ...... 181 Anomalies of the Posterior Fossa ...... 195 Anomalies of the Gyration ...... 197 Ultrasound Images ...... 206 Intracranial Expansive Processes ...... 223 Brain Tumors ...... 223 Tuberous Sclerosis ...... 227 Corpus Callosum Lipomas ...... 228 Arachnoid Cysts ...... 231 Hematomas ...... 234 Cysts of the Germinal Zone ...... 235 ...... 236 Infectious Pathologies ...... 237 Cytomegalovirus (CMV) ...... 237 Toxoplasmosis ...... 252 Hemorrhagic and Ischemic Pathologies ...... 258 Hemorrhagic Pathologies ...... 258 Ischemic Pathologies ...... 262 Vascular Pathologies ...... 266 Vein of Galen Aneurysms ...... 266 Thrombosis of the Dural Sinuses ...... 268 Other Vascular Lesions ...... 269 Biometric Anomalies ...... 271 ...... 271 Major ...... 276 Gyration Disorders ...... 279 Three Groups: Type I (LIS I), II (LIS II), and III (LIS III) ...... 279 Heterotopia ...... 283 ...... 284

Part III Biometric Tables

8 Biometric Tables ...... 289 Biparietal Diameter (Snidjers) ...... 290

Conclusion ...... 301 Index ...... 311