and Marcelo Zugaib4
(1)
São Paulo University, Bauru, Brazil
(2)
Parisian University, Bauru, France
(3)
Member of International Fetal Medicine and Surgery Society, Bauru, Brazil
(4)
Obstetrics, University of São Paulo, Bauru, Brazil
Malformations of the central nervous system, in terms of frequency, are second only to malformations of the urinary tract.
The spectrum of neurological disorders that can be identified in the prenatal period is as wide as the variety of clinical conditions and prognoses. The degree of intellectual, motor, and even real chances of survival for individuals affected is not possible to define in many cases.
Central nervous system malformations include: midline anomalies, posterior fossa, hydrocephalus, destructive abnormalities, the addition of anomalies (cysts, tumors), anomalies of the cranial contour (encephalocele), and, in particular, neural tube defects (addressed in Chap. 4).
3.1 Anomalies of the Cerebral Midline/Anomalies of Ventral Induction of the Fetal Brain: Holoprosencephaly
Holoprosencephaly is an anomaly caused by a failure of embryonic prosencephalic cleavage during the process of formation of the brain and lateral ventricles of the hemispheres. Rare in newborns (1/16,000), it has an impact on miscarriage specimens in about 7.3/1,000 cases.
Fig. 3.1
Cross-section of the fetal cephalic pole, with the posterior portion (P) more caudally inclined, showing the cerebellum (between the black arrows) and midbrain (between the white arrows). The letter T indicates the caudal and posterior portions of the thalamus
Fig. 3.2
Same section as in the Fig. 3.1 showing the cerebellar or cistern magna (white arrow indicating hypoechoic area posterior to the cerebellum), cerebellar vermis (V), cavum septum pellucidum (CSP), and insular lobe (black arrow), medially to the lateral sulcus of Sylvius
Fig. 3.3
Cross-section of the fetal cephalic pole a little laterally shifted demonstrating the posterior horns of the lateral ventricles in their normal 26-week aspect (arrow). SB = white matter, P = choroid plexus
Fig. 3.4
Same section of last figure showing the proper way to measure of posterior horn of the lateral ventricle (arrow, Atrio Ventricular). Atrium is measured where choroid plexus ends (P) from the medial to the lateral wall of the ventricle (calipers)
Fig. 3.5
Transverse oblique section of the cephalic pole demonstrating a normal central nervous system, cavum septum pellucidum (CV), thalamus (TL), lateral sulcus of Sylvius (FS), cerebellar peduncle (PC), hippocampal gyrus (HC), posterior fossa (FP)
Fig. 3.6
Transverse view of the cephalic pole of a fetus at 21 weeks, more cranial than that shown in Fig. 3.5 demonstrating two elongated hyperechogenic areas in both hemispheres corresponding to the choroid plexus (CP, arrows) normally seen in the bodies of the lateral ventricles
Fig. 3.7
Transverse view of the fetal cephalic pole demonstrating the thalami (red arrows) and the normal anterior horns of the lateral ventricles (blue arrows)
Fig. 3.8
Low cross-section of the fetal cephalic pole, at the skull base level, demonstrating the circle of Willis (Willis polygon, arrows)
Fig. 3.9
Illustration of a technical measurement of interorbital distance (DIO), correlating the distance from the center of an eyeball to the other (pictured right) with the biparietal diameter (BPD; pictured left). The normal relationship DIO/BPD is 0.47 with a deviation of 0.02 and is used to define normal, hyper- or hypotelorism
Fig. 3.10
Transverse view of the fetal cephalic pole with a slight caudal inclination in the posterior portion, showing the measurement of the nuchal fold (calipers). A = anterior or front, P = posterior or occiput
Fig. 3.11
Same section as in Fig. 3.10 showing the posterior fossa and the normal appearance of the cerebellum and cisterna magna (horizontal calipers), with their respective measurements (cerebellar hemispheres; V = cerebellar vermis)
Fig. 3.12
Sagittal section of the cephalic fetal pole showing normal corpus callosum (arrows) and cavum septum pellucidum (CSP) at different gestational ages. Gestational age here is 22 weeks and 6 days
Fig. 3.13
Sagittal section of the cephalic fetal pole showing normal corpus callosum (arrows) and cavum septum pellucidum (CSP) at 25 weeks’ gestation
Fig. 3.14
Sagittal section in the cephalic fetal pole showing a normal corpus callosum (arrows) and cavum septum pellucidum (csp) in a normal 30-week fetus
Fig. 3.15
Transverse view of the fetal cephalic pole demonstrating colpocephaly in a case of agenesis of the corpus callosum
Fig. 3.16
Transverse view of the fetal cephalic pole demonstrating the bull horn sign, a habitual aspect in cases of agenesis of the corpus callosum
Fig. 3.17
Cross-section of the cephalic pole with a caudal inclination in the posterior portion showing bilateral ventriculomegaly (VL) with the choroid plexus “pending” (P)
Fig. 3.18
Axial section of the fetal cephalic pole demonstrating mild ventriculomegaly with 10.7 mm, the ventriculomegaly is considered mild up to 15 mm
Fig. 3.19
Sometimes a mild ventriculomegaly is associated with third ventricle cysts
Fig. 3.20
Transverse view of the fetal cephalic pole demonstrating bilateral ventriculomegaly. The arrows indicate the medial wall of the lateral ventricle. V = dilated ventricles
Fig. 3.21
Cross-sections of the fetal head showing ventricular dilation. Note that the dilatation of the proximal lateral ventricle to the transducer may go unnoticed because of the posterior artifact to the cranial bone plate of the same side, requiring a sagittal paramedian section to confirm the bilateral ventriculomegaly. The arrow indicates the lateral wall of the lateral ventricle
Fig. 3.22
Transverse view of the fetal cephalic pole demonstrating severe ventriculomegaly (measurement of caliper A) and the cerebral hemisphere (caliper B). This is the correct location of insonation to accomplish the measurement of the ventricular hemisphere relationship
Fig. 3.23
(a, b) Cross-sections of the fetal cephalic pole showing accentuated ventriculomegaly with severe impairment of the brain parenchyma. Arrows show the lateral ventricle wall and underlying the remaining brain parenchyma (arrows) in Fig. 3.23 are shown the measurements of the ventricular/hemisphere ratio (calipers)
Fig. 3.24
Cross-sections of the fetal cephalic pole showing accentuated ventriculomegaly with severe impairment of the brain parenchyma. Arrows show the lateral ventricle wall and underlying remaining brain parenchyma (arrows). As in Fig. 3.23, the measurements of the ventricular/hemisphere ratio (calipers) are shown
Fig. 3.25
Transverse view of cephalic pole showing arachnoid cyst., Note its posterior position in relation to the occipital horn of the lateral ventricle (VL) The orbits = C = cyst
Fig. 3.26
Transverse view of fetal cephalic pole showing Typical schizencephaly aspect (esa), this defect is supposed to occur by obstruction of the area irrigated by the internal carotid and middle cerebral artery. PC = choroid plexus and cerebellar peduncle, tl = thalamus
Fig. 3.27
A case of porencephaly (POR) which image is similar to Fig. 3.26. Notice that the main difference is that in porencephalic brains the fluid (POR) image is close to the parietal bone practically drawing the mean cerebral artery irrigation territory (here replaced by fluid)
Fig. 3.28
Transverse view of the fetal cephalic pole demonstrating unilateral right ventriculomegaly (VLD). A = anterior, P = posterior
Fig. 3.29
Transverse view of the fetal cephalic pole, where unilateral ventriculomegaly (calipers 1) is observed. Note the normal contralateral ventricle (calipers 2)
Fig. 3.30
Transverse view of the cephalic pole showing the typical aspect of hydroanencephaly where very little (b, P) or no cerebral parenquyma (a) is observable (just water)
