Journal of Medical Ultrasound (2012) 20, 150e154
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ORIGINAL ARTICLE
Prenatal Diagnosis of Fetal Encephalocele Using Three-dimensional Ultrasound Sing-Ling Liao 1, Pei-Yin Tsai 1*, Yueh-Chin Cheng 1, Chiung-Hsin Chang 1, Huei-Chen Ko 2,3, Fong-Ming Chang 1,2,3 1 Department of Obstetrics and Gynecology, National Cheng Kung University Medical College and Hospital, 2 Department of Psychology, Asia University, Taichung, and 3 Institute of Behavior Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
Received 15 January, 2012; accepted 30 May, 2012
KEY WORDS encephalocele, three dimensional ultrasound
Fetal encephalocele, with high risk of mortality and morbidity, is one of the most serious congenital neural tube defects. Prenatal diagnosis of encephalocele is important in fetal medicine. In this study, we detected encephalocele using three-dimensional ultrasound (3D US). We reviewed our medical records of prenatal diagnosis of fetal encephalocele in National Cheng Kung University Hospital from May 2000 to November 2011. All the cases were scanned by two-dimensional and 3D US. In total, 10 cases of fetal encephalocele were diagnosed and enrolled for analysis. The range of gestational age at prenatal diagnosis by US was 12e27 weeks, and one case was diagnosed in the first trimester. Among them, 70% were occipital encephalocele, 10% frontal encephalocele, and 20% parietal encephalocele. Compared with previous studies, 3D US can detect fetal encephalocele early and provide additional vivid illustrations after various modes of reconstruction. In conclusion, 3D US may contribute to early detection of fetal encephalocele and provide visual depiction, thus, assisting substantially with prenatal diagnosis as well as genetic consultation. ª 2012, Elsevier Taiwan LLC and the Chinese Taipei Society of Ultrasound in Medicine. All rights reserved.
Introduction
* Correspondence to: Dr. Pei-Yin Tsai, Department of Obstetrics and Gynecology, National Cheng Kung University Medical College and Hospital, 138 Victory Road, Tainan 70428, Taiwan. E-mail address:
[email protected] (P.-Y. Tsai).
Encephalocele is characterized as a protrusion of the brain and/or meninges through a defect in the skull that is covered with skin. It is one of the most severe neural tube defects, with a prevalence estimated to be 0.8e5 per 10,000 live births [1]. Prenatal diagnosis of encephalocele is
0929-6441/$36 ª 2012, Elsevier Taiwan LLC and the Chinese Taipei Society of Ultrasound in Medicine. All rights reserved. http://dx.doi.org/10.1016/j.jmu.2012.07.005
Prenatal Diagnosis of Encephalocele by 3D US
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accomplished by maternal screening of serum a-fetoprotein levels and ultrasound (US). With two-dimensional ultrasound (2D US), encephalocele appears as a defect in the calvarium containing a cystic or solid mass with a gyral pattern that is contiguous with the brain [2]. Prenatal 2D US detects approximately 80% of encephaloceles. The diagnosis is easily and confidently made from sonographic findings during the second trimester and can also be made in the first trimester [3]. The prognosis for patients with encephalocele depends on the extent of herniated neural tissue in the sac and on the presence of associated anomalies. In a previous series, 83% of patients with encephaloceles had mental handicap and/or physical impairment [4]. The mortality rate of encephalocele was 29% [5]. Seizure disorders are present in about 20% of infants with congenital encephalocele [6]. With the advent of three-dimensional (3D) US, various rendering modes of imaging may improve imaging depiction. Since 1992, we have used 3D US in prenatal diagnosis of congenital anomalies, assessing fetal organ volume, predicting fetal weight, as well as prenatal detection of fetal growth restriction [7e25]. In the present series, we collected and analyzed retrospectively cases of encephalocele diagnosed by 3D US from May 2000 to November 2011. Although isolated cases of encephalocele diagnosed by 3D US have been reported previously [26], to the best of our knowledge, this series is one of the largest of prenatal diagnosis of encephalocele using 3D US in the medical literature.
Materials and methods From May 2000 to November 2011, the medical records of patients with fetal encephalocele were reviewed. The cases were from the Antenatal Clinic of National Cheng Kung University Hospital, which is a tertiary medical center in Southern Taiwan. All the US examinations were undertaken in the Antenatal Ultrasound Laboratory of Obstetrics and
Table 1
Gynecology, National Cheng Kung University Hospital, Tainan, Taiwan. All the fetuses were followed to the end of pregnancy to confirm the diagnosis of encephalocele. As encephalocele may be associated with other malformations that may be part of other syndromes [1,27,28], systematic scanning was performed for every individual. In other words, not only the central nervous system, but also fetal cardiovascular, gastrointestinal, genitourinary and musculoskeletal systems, as well as craniofacial deformities were examined. For 3D US examinations, we used a 3.5e7.0-MHz Voluson US scanner (Kretz Voluson 530D; Zipf, Austria) and a 4e8-MHz transabdominal or transvaginal US scanner (Voluson 730 Expert; GE Medical Systems, Milwaukee, WI, USA). The fetus with encephalocele was initially scanned by 2D US to locate the region of interest (ROI). Then, the 3D probe was used to scan all the ROIs systematically and mechanically. All the images were stored for further 3D visualization and reconstruction by a variety of rendering modes of 3D US, including surface-rendering, transparent, X-ray, gradient-light, or maximal intensity mode, or as a mixture of several modes.
Results In total, 10 fetuses were depicted in utero to have fetal encephalocele by 3D US in 11 years. All the results of this series are summarized in Table 1. The range of gestational age was 12e27 weeks and the mean was 20 weeks. Six cases (60%) were diagnosed before 20 weeks gestation. Maternal ages ranged from 21 to 34 years (mean: 29 years). Among the 10 mothers, six (60%) were multiparous. 2D US was used to scan the ROI (Fig. 1). 3D US imaging was undertaken to provide additional illustrations after various modes of reconstruction (Fig. 2). The 3D US images allowed the parents to have a better understanding of the fetal malformation, especially with the images of surface reconstruction.
Prenatal diagnosis of encephalocele by 3D US.
Case no.
Maternal Age (y)
Obstetric history
Gestational age (wk)
US indication
Type of encephalocele
Associated anomalies
Outcome
1
21
G1P0
25
Referral
Occipital
TOP
2
34
G2P1
25þ6
Referral
Occipital
3 4
28 29
G2P1 G1P0
18þ5 17þ6
Referral Referral
Occipital Frontal
5 6 7 8
31 32 32 28
G4P1SA1AA1 G2P1 G1P0 G2P1
18 12þ2 18þ6 19
Referral Routine Referral Referral
Parietal Parietal Occipital Occipital
9
31
G2P1
20
Referral
Occipital
10
24
G3P0AA2
27
Referral
Occipital
Single umbilical artery Cystic hygroma MeckeleGruber syndrome (polycystic kidney disease, club feet, polydactyly) d Amniotic band syndrome, facial distortion, cleft lip and palate d d d Hydrocephalus, absence of 5th mid phalanx Oligohydramnios, cystic hygroma, pleural effusion Meningocele, cystic hygroma
3D US Z three-dimensional ultrasound; A Z abortion; G Z gravida; PZ para; TOP Z termination of pregnancy.
TOP
TOP TOP
TOP TOP TOP TOP TOP TOP
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S.-L. Liao et al. polydactyly and club feet were detected. MeckeleGruber syndrome was diagnosed.
Discussion
Fig. 1 Transverse view of a fetus with occipital encephalocele of 18þ5 weeks of gestation (Case 3) by two-dimensional ultrasound shows a defect in the calvarium containing a cystic or solid mass with a gyral pattern that is contiguous with the brain.
Among these 10 cases, seven (70%) were occipital encephalocele, one (10%) was frontal encephalocele, and two (20%) were parietal encephalocele. In addition, for associated anomalies, 60% were noted to be associated with other malformations. In other words, 30% were associated with cystic hygroma, 10% with single umbilical artery, 10% with amniotic band, cleft lip and palate and facial distortion, and 10% with hydrocephalus. In Case 2, occipital encephalocele with polycystic kidney disease,
Fig. 2 Surface rendering mode of the same fetus in Fig. 1 (Case 3) using three-dimensional ultrasound shows a protruding mass in the occipital area, representing occipital encephalocele.
Encephaloceles are divided into three major types: sincipital (frontoethmoidal), basal (trans-sphenoidal, sphenoethmoidal, transethmoidal, and spheno-orbital), and occipital. Occipital encephaloceles are the most frequent type (w85%) in North America and Western Europe [29]. By contrast, in Southeast Asia, parts of Russia, and Central Africa, frontal encephaloceles are more frequent than occipital type [29]. In our series, seven cases (70%) were occipital encephalocele, one (10%) was frontal, and two (20%) were parietal, which is similar to the series in North America and Western Europe. To date, the underlying mechanism causing congenital encephalocele is still uncertain, although it involves defective closure of the anterior neural tube. Some have proposed that the onset of the most severe lesions may occur prior to 26 days after conception, whereas the less severe lesions that primarily involve skull or meninges may occur later [30,31]. If the encephalocele is bulky, with severe microcephaly or other lethal anomalies, termination of pregnancy may be the choice due to the severe morbidity and mortality. However, postpartum surgical treatment is appropriate for cases with relatively small encephalocele and without other associated lethal anomalies. The procedure basically consists of removing the overlying sac and closing the defect including the dural defect [32]. Therefore, vaginal delivery may be considered if the lesion is relatively small. By contrast, large fetal encephaloceles may require cesarean section to deliver the baby. Factors related to the prognosis and outcome for babies with encephalocele include the size of the sac, the contents of the neural tissue, hydrocephalus, infection, and the presence of associated anomalies. Lo and colleagues [6] have reported that hydrocephalus and other intracranial abnormalities may predict neurodevelopmental outcome, but not the type of the encephalocele [6]. Cognitive development was abnormal in 52% of patients, with mild, moderate or severe mental delay in 11%, 16% and 25% of patients, respectively [6]. In another series, French reported 83% of encephalocele infants were mentally and/or physically impaired [4]. Kiymaz and co-workers reported that the mortality rate of occipital encephalocele was 29% [5]. In our series, all the cases were severe encephalocele, with a large herniated sac and brain tissue. Therefore, all the parents selected termination after US examination and prenatal consultation. Although prenatal detection of fetal encephalocele has been made by 2D US since 1992 [33], prenatal illustration of fetal encephalocele by 3D US has not been reported before 2006 [26]. In 2006, Tsai and colleagues [26] first reported a case of fetal frontal encephalocele using 3D US at 17 weeks gestation. In 2010, fetal occipital encephalocele diagnosed at 13 weeks gestation using 3D US was reported by Sorak and coworkers [34]. In 2011, Borowski and colleagues [3] presented two cases of occipital encephalocele diagnosed at 12 and 13 weeks gestation using 3D US.
Prenatal Diagnosis of Encephalocele by 3D US In our series, the gestational age at prenatal diagnosis by 3D US was 12e27 weeks, with a mean of 20 weeks. In total, 90% of cases were diagnosed at the second trimester. Only 10% were diagnosed at the first trimester. Encephalocele is frequently associated with other malformations that may be part of recognized syndromes [1,27,28]. The most common of the associated syndromes is MeckeleGruber syndrome, which includes occipital encephalocele, microcephaly, microphthalmia, polycystic kidneys, ambiguous genitalia, polydactyly, cleft lip and palate, and other malformations [35]. Other cerebral malformations are often associated with encephalocele such as hydrocephalus, corpus callosal abnormalities, and cerebral dysgenesis [6,35]. In our series, only four cases (40%) were isolated encephalocele and 60% were associated with other malformations. Three cases (30%) had cystic hygroma, one (10%) had single umbilical artery, one (10%) had amniotic band, cleft lip and palate and facial distortion, and one (10%) had hydrocephalus. In Case 2, 3D US revealed occipital encephalocele with polycystic kidney disease, polydactyly and club feet, and MeckeleGruber syndrome was diagnosed. Our frequencies of associated anomalies are different from other studies. Further studies are warranted to investigate the anomalies associated with fetal encephalocele. In conclusion, in order to compare with previous reports of fetal encephalocele diagnosed prenatally using 3D US, we retrospectively analyzed our cases of encephalocele and proved the diagnostic feasibility of 3D US. In addition, this may be the first and probably the largest series of cases of fetal encephalocele diagnosed prenatally by 3D US thus far. From the results of this study, we believe that 3D US may be an important diagnostic tool for clinical application in fetal medicine.
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Acknowledgments [19]
We are grateful to the staff of Ultrasound Laboratory of Obstetrics and Gynecology, National Cheng Kung University Hospital. This study was partly supported by a grant from National Science Counsel, Executive Yuan, Taipei, Taiwan.
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