Closure of the cerebellar vermis: evaluation with second trimester US.

Bromley, Bryann; Nadel, A.; Pauker, Susan P.; Estroff, J A; Benacerraf, Beryl R.

doi:10.1148/radiology.193.3.7972820

Cited by 143 publications

(99 citation statements)

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“…This counseling to parents is important both for obtaining appropriate knowledge of the potential outcomes in the neonate and child and for making informed decisions regarding future management of the pregnancy. Although a number of studies have compared the findings of fetal sonography and postnatal MRI [11,13,18,19] and of fetal imaging versus pathology results [8,10,20,21], there is a paucity of data comparing the findings on MRI performed during the fetal period versus postnatal MRI in pregnancies that result in delivery of live-born infants.Several objectives were the focus of this study. First, we aimed to describe the prevalence and spectrum of posterior fossa anomalies on sonography and MRI in a major referral center for fetal care over a 5-year period.…”

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confidence: 99%

How Accurately Does Current Fetal Imaging Identify Posterior Fossa Anomalies?

Limperopoulos

Robertson

Khwaja

et al. 2008

American Journal of Roentgenology

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OBJECTIVE-The first objective of our study was to describe the prevalence and spectrum of posterior fossa anomalies over 5 years in a major fetal care center where the referral diagnosis (by fetal sonography) was investigated by fetal MRI and, if confirmed, by postnatal MRI if possible. The second objective was to assess the accuracy with which fetal MRI predicts postnatal MRI findings in this population. MATERIALS AND METHODS-We retrospectively identified all cases of suspected fetal posterior fossa anomalies referred to our center from 2002 through 2006. We reviewed maternal, fetal, neonatal, and follow-up records of all cases and fetal and early postnatal imaging studies.RESUlTS-Of the 90 cases of suspected fetal posterior fossa anomalies (by fetal sonography) referred over the study period, 60 (67%) were confirmed by fetal MRI. Of 42 live-born infants, 39 (93%) underwent postnatal MRI. There was complete agreement in fetal and postnatal MRI diagnoses in 23 infants (59%). In 16 cases (41%), fetal and postnatal MRI diagnoses disagreed; postnatal MRI excluded fetal MRI diagnoses in six cases (15%) and revealed additional anomalies in 10 cases (26%).CONClUSION-Although a valuable adjunct to fetal sonography in cases of suspected posterior fossa anomaly, current fetal MRI, particularly in early gestation, has limitations in accurately predicting postnatal MRI abnormalities. Advancing the accuracy of MRI for the diagnosis of posterior fossa anomalies will require greater understanding of normal brain development and improved tissue resolution of fetal MRI. During the interim, our findings strongly support the need for postnatal MRI follow-up in cases with suspected posterior fossa anomalies by fetal MRI. Posterior fossa malformations are among the most common brain anomalies identified by current fetal imaging techniques. Advances in MRI during fetal and early postnatal life continue to provide important insights into normal and abnormal development of the cerebellum and brainstem [1][2][3][4][5][6]. Despite the rapid progress in fetal imaging, the prenatal diagnosis of posterior fossa dysgenesis remains challenging due to both false-positive and false-negative diagnoses [7][8][9][10][11][12][13]. As a result, a variety of classification schemes have been proposed for posterior fossa anomalies 14-17] without any scheme receiving widespread acceptance to date. KeywordsAbnormalities of posterior fossa development can, in general, be divided into those in a small posterior fossa with "crowding" of its contents (e.g., Chiari's malformations) versus those occurring in a normal or enlarged posterior fossa. The latter category, which is the focus of this study, may be further subcategorized into anomalies in a posterior fossa with normal fluid spaces versus those associated with enlarged (relatively or absolutely) posterior fossa fluid spaces.The primary reason for performing fetal imaging is to gather accurate information about fetal structure on which to base reliable counseling. This counseling to parents is i...

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confidence: 99%

How Accurately Does Current Fetal Imaging Identify Posterior Fossa Anomalies?

Limperopoulos

Robertson

Khwaja

et al. 2008

American Journal of Roentgenology

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“…Increased NT, together with other extracranial findings such as polydactyly, may aid earlier diagnosis especially when a prior family history is present. However, it is not possible to demonstrate Vermian hypoplasia before the 18 th gestational week (18). Due to the marked heterogeneity in this group of disorders and the relatively high frequency of associated medical condi- tions, it is difficult to make generalizations about outcomes.…”

Section: Discussionmentioning

confidence: 99%

Joubert syndrome and related disorders, prenatal diagnosis with ultrasound and magnetic resonance imaging

İskender

Tarım

Alkan

2011

J Turkish German Gynecol Assoc

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Joubert syndrome (JBTS) is an autosomal recessive disorder characterized by intellectual disability, hypotonia, ataxia, tachypnea/apnea, and abnormal eye movements. A pathognomonic midbrain-hindbrain malformation seen on cranial magnetic resonance imaging (MRI), which consists of hypoplasia of the midline cerebellar vermis that resembles the cross-section through a molar tooth, has been described previously.The molar tooth sign is defined by a peculiar appearance resembling a molar tooth secondary to an abnormally deep interpeduncular fossa and enlarged superior cerebellar peduncles on axial images at the pontomesencephalic level. The term Joubert Syndrome and Related Disorders (JSRD) has recently been adopted to describe all disorders presenting the "molar tooth sign" (MTS) on brain imaging. JSRD is characterized by lack of decussation of the superior cerebellar peduncles, central pontine tracts and corticospinal tracts suggesting defective axon guidance. Prenatal sonographic findings in fetuses with JSRD are relatively nonspecific and include increased nuchal translucency, enlarged cisterna magna, cerebellar vermian agenesis, occipital encephalocele, ventriculomegaly and polydactyly. We report a case of JSRD detected prenatally at 23 weeks of gestation. The fetus in the present case had a normal karyotype. Sonographic features of the fetus included polydactyly, partial vermian hypoplasia, dilated 4 th ventricle and mild ventriculomegaly which were also confirmed by prenatal MRI. MTS was demonstrated in a postnatal MRI after pregnancy termination. (J Turkish-German Gynecol Assoc 2012; 13: 135-8)

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“…5 Identification of the fetal fourth ventricle is essential for the characterization of abnormalities of the posterior fossa, cystic masses, hydro-cephaly, and enlarged fourth ventricles. However, little information is found in the English literature 2,[6][7][8][9][10][11][12] regarding the normal size of the fourth ventricle throughout gestation, and no nomograms could be found in the published works.…”

Section: Discussionmentioning

confidence: 99%

Ultrasonographic Nomograms of the Fetal Fourth Ventricle

Goldstein

Makhoul

Tamir

et al. 2002

J of Ultrasound Medicine

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Objective. To characterize normal growth of the fetal fourth ventricle on ultrasonography throughout pregnancy. Methods. Consecutive biometric measurements and fetal organ scans were obtained from 299 patients undergoing fetal anatomic surveys between 13 and 40 weeks' gestation. Using 7-and 3.5-MHz transducers for early (13-to 17-week) and late (>17-week) examinations, respectively, we scanned the fetal head in the axial plane with special focus on the posterior fossa of the brain. The fourth ventricle was identified, and its anteroposterior diameter and width were measured. A "triangle" formula was used for calculating its circumference and area. Results. The fourth ventricle was shown as a hypoechoic triangle below the level of the cerebellum. A linear regression line of the fourth ventricle was observed across gestational age, and a first-degree correlation was found between gestational age and anteroposterior diameter of the fourth ventricle (r = 0.894; P < .0001; y = -0.84 + 0.23 × gestational age), its width (r = 0.657; P < .0001; y = 3.82 + 0.14 × gestational age), its circumference (r = 0.843; P < .0001; y = 5.11 + 0.58 × gestational age), and its area (r = 0.844; P < .0001; y = -10.11 + 1.17 × gestational age). Twelve enlarged fourth ventricles were found between 14 and 16 weeks, but results of follow-up scans at 20 weeks were normal. Conclusions. An isolated enlarged fourth ventricle in the early second trimester might represent a normal variant; it should be followed, but decisions about the fate of the pregnancy should not be based solely on this finding. Key words: central nervous system; fetus; fourth ventricle; prenatal diagnosis; ultrasonography.Received December 27, 2001, from the Department of Obstetrics and Gynecology, Rambam Medical Center, Haifa, Israel (I.G., I.R.M., B.-S.R.); Department of Epidemiology, Technion Faculty of Medicine, Haifa, Israel (A.T.); and Department of Obstetrics and Gynecology, Hospital Dr R. A. Calderon, San Jose, Costa Rica (D.N.) he fourth ventricle is derived from the rhomboencephalon, the most caudal primary vesicle formed after complete fusion of the neural folds and closure of the caudal neuropore.1 Anatomically, the fourth ventricle is considered a fluid-filled cavity that extends from the aqueduct of Sylvius to the foramen of Magendie and separates the brain stem from the cerebellum. It has a "tentlike" appearance, and the lateral walls are formed by the cerebellar peduncles. The roof is formed by the cerebellar peduncles, the medullary velum, and the cerebellar nodules; the floor is delineated by the surface of the pons and the medulla oblongata. The posterolateral extensions of the fourth ventricle are known as the posterior superior recesses.

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Closure of the cerebellar vermis: evaluation with second trimester US.

Abstract: The prenatal diagnosis of Dandy-Walker variant should not be made before 18 weeks gestation because the development of the cerebellar vermis may be incomplete at that time.

Cited by 143 publications

References 0 publications

How Accurately Does Current Fetal Imaging Identify Posterior Fossa Anomalies?

How Accurately Does Current Fetal Imaging Identify Posterior Fossa Anomalies?

Joubert syndrome and related disorders, prenatal diagnosis with ultrasound and magnetic resonance imaging

Ultrasonographic Nomograms of the Fetal Fourth Ventricle

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