PRENATAL DIAGNOSIS
Prenat Diagn 2003; 23: 779–783. Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/pd.697
SHORT COMMUNICATION
Prenatal diagnosis of cavum velum interpositum cysts: significance and outcome Vered H. Eisenberg1 *, Yaron Zalel1 , Chen Hoffmann2 , Zeev Feldman3 and Reuwen Achiron1 1 Departments of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel Hashomer, and Sackler Faculty of Medicine, Tel Aviv University, Israel 2 Departments of Radiology, The Chaim Sheba Medical Center, Tel Hashomer, and Sackler Faculty of Medicine, Tel Aviv University, Israel 3 Departments of Neurosurgery, The Chaim Sheba Medical Center, Tel Hashomer, and Sackler Faculty of Medicine, Tel Aviv University, Israel
Objectives
To describe a fetal cavum velum interpositum cyst (CVIC) and to review its clinical significance.
Methods Description and follow-up of two cases with prenatal diagnosis of a midline cyst in the fetal brain, at the Chaim Sheba Medical Center. The cases were reviewed and followed-up by a multidisciplinary team that included sonographers, pediatric neurologists, pediatric neurosurgeons, radiologists, and clinical geneticists. Medline search of cases of cysts of the cavum velum interpositum as reported in the English literature. Results Two patients referred for consultation owing to midline cysts were diagnosed with isolated cysts of the cavum velum interpositum without other anomalies. Magnetic resonance imaging (MRI) of the fetal brain did not reveal any additional malformations in either case. Prenatal follow-up showed the cysts to be stable in one case and decreased in size in the other. Postnatal neurodevelopmental outcome to date is normal. (Range of follow-up: 6–24 months.) Eight cases reported in the literature as CVIC resulted in favorable prognosis in all without further intervention. However, one infant required ventriculoperitoneal shunting due to progressive hydrocephalus, but developed normally nonetheless. Conclusion Prenatal diagnosis of cysts of the cavum velum interpositum, which are isolated, single, stable in size, and not associated with other anomalies, is consistent with a favorable postnatal outcome. Copyright 2003 John Wiley & Sons, Ltd. KEY WORDS: cavum velum interpositum cyst; prenatal diagnosis; neurodevelopmental outcome; asymmetric ventricles; interhemispheric cysts
INTRODUCTION The prenatal sonographic detection of midline cystic lesions of the fetal brain presents a diagnostic challenge. The cavum velum interpositum (CVI) represents a potential space above the tela choroidea of the third ventricle and below the columns of the fornices. A cystic structure in this region may raise concerns about the presence of other pathological conditions. Interhemispheric supratentorial fluid collections may represent physiologic median structures, which have no clinical significance, such as an enlarged cavum vergae (Sahinoglu et al., 2002). However, interhemispheric cysts, such as glioependymal and arachnoid cysts, which cause early ventriculomegaly, may carry a worse prognosis (Hassan et al., 1996). Differentiating between pathological and physiological conditions is imperative in order to counsel the *Correspondence to: Vered H. Eisenberg, Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel Hashomer, 52621 Ramat-Gan, Israel. E-mail:
[email protected]
Copyright 2003 John Wiley & Sons, Ltd.
patients and manage the pregnancy accordingly. Since the literature on cavum velum interpositum cysts (CVIC) is scarce, our aim in this report was to improve our knowledge of the prenatal diagnosis and the neurodevelopmental outcome of these findings. The available literature was reviewed with an emphasis on the clinical significance.
CASE REPORTS
Case 1 A 27-year-old woman, at 24 gestational weeks, was referred for evaluation because of asymmetric cerebral ventricles. She was previously healthy, was pregnant for the first time, and her family history was unremarkable. The maternal serum alpha-fetoprotein test and an amniocentesis performed at her request had both been normal. The TORCH screen was negative for cytomegalovirus and toxoplasma. A systemic fetal sonographic evaluation, which had prompted her referral, revealed lateral Received: 24 January 2003 Revised: 23 June 2003 Accepted: 30 June 2003
780
V. H. EISENBERG ET AL.
ventricles measuring 8 to 9 mm on the left side and 6 mm on the right, both within normal limits. A midsagittal view revealed a cystic lesion 3 × 6 mm, located supratentorially in the midline above the pineal body, between the cerebral hemispheres (Figure 1). On posterior coronal view, a hypoechoic lesion was seen in the midline, measuring 6 mm (Figure 2). These findings were consistent with a CVIC. The third ventricle was pronounced and the fourth was not enlarged. The corpus callosum was clearly seen and the rest of the brain anatomy was normal. A detailed anatomic survey ruled out other malformations. Repeat evaluation at 28 weeks’ gestation showed similar findings with normal brain development and normal fetal growth parameters. Magnetic resonance imaging (MRI), which was performed at 30 weeks’ gestation, did not reveal any additional pathologic findings (Figure 3). During repeat evaluation at 32 weeks’ gestation, the lesion measured 8 × 6 mm and the asymmetry in the cerebral ventricles remained unchanged. A female child weighing 3300 g was born Anterior
Posterior
Figure 1—Transvaginal sonogram in midsagittal view showing a supratentorial cystic lesion (c), located above the pineal body and beneath the cavum septum pellucidum (sp), consistent with a CVIC
at 41 weeks’ gestation by vacuum extraction. Ultrasound of the infant’s brain was normal at two months of age. The neurological examination was normal at the last follow-up at six months of age.
Case 2 A 28-year-old woman at 19 weeks’ gestation was referred for consultation because of a cystic lesion in the fetal brain, which was seen on a routine scan. She was generally healthy and had previously had a normal vaginal delivery, with a healthy baby, and one first-trimester miscarriage. The current pregnancy was spontaneous and had run a normal course until her referral. She had not performed a maternal serum alpha-fetoprotein test. Her first sonogram revealed a clear cystic lesion 8 × 4 mm located above the third ventricle in the midline and slightly to the right between the cerebral hemispheres, in the area of the cavum velosum. The lateral ventricles measured 7 to 8 mm, the right being somewhat more pronounced. The third and fourth ventricles were not enlarged. The corpus callosum was seen and it measured 1.2 cm in length and in width, corresponding with 19 gestational weeks’ measurements (Figures 4, 5 and 6). A detailed anatomic evaluation revealed no other findings. A second examination two weeks later showed that the lesion had become significantly smaller, now measuring 3 to 4 mm. The couple was counseled that the finding was probably not significant and they chose to continue the pregnancy. Consecutive sonograms at 23 and 27 gestational weeks were similar. MRI performed at 30 weeks’ gestation revealed normal brain anatomy without additional pathologic findings without visualization of the CVIC. On repeat transvaginal sonography at 33 weeks’ gestation, the lesion was no longer visible. The fetal biometric parameters were normal for gestational age. A male child was born at 39 weeks’ gestation by normal vaginal delivery, weighing 3430 g. MRI performed at 23 months of age was normal. The child has normal neurodevelopmental milestones and is now almost two years old.
DISCUSSION
Figure 2—Transvaginal posterior coronal sonographic image showing a hypoechoic lesion in the midline measuring 6 mm Copyright 2003 John Wiley & Sons, Ltd.
The velum interpositum, the choroid plexus of the third ventricle, forms the roof of the third ventricle, extending from above the pineal body, anteriorily, to the foramen of Monro, posteriorily (Hertzberg et al., 1997; Vergani et al., 1999). During intrauterine life, it becomes visible only when cysts develop. A potential space is formed between the layers of the tela choroidea, an extension of the quadrigeminal plate cistern, and when this space is filled with fluid the term cavum velum interpositum (CVI) is applied. The CVI can be seen in 2 to 3% of children above two years of age and is usually an incidental finding (Hertzberg et al., 1997). However, it has been reported in association with mental and motor development retardation, epilepsy, and infantile autism (Gangemi et al., 1997; Meller et al., 1985). Prenat Diagn 2003; 23: 779–783.
PRENATAL DIAGNOSIS OF CAVUM VELUM INTERPOSITUM (a)
781
(b)
(c)
Figure 3—MRI in (a) axial; (b) coronal; and (c) sagittal views: the CVIC is marked by the arrowhead
Various pathological processes can originate in the velum interpositum and, when obstruction of the ventricles occurs as a result of these, hydrocephalus may develop. Arachnoid cysts (Spiegel et al., 1988; Hassan et al., 1996), arterio-venous malformations (Lunsford et al., 1977), meningiomas (Mallucci and Obukhov, 1995), and hemorrhages (Berne and Lourie, 1966) have all been reported. Cysts in the velum interpositum have been described in neonates and adults and, more recently, in utero (Chen et al., 1998; Spiegel et al., 1988; Lees et al., 1978; Hertzberg et al., 1997; Vergani et al., 1999). Copyright 2003 John Wiley & Sons, Ltd.
The differential diagnosis of midline cystic brain lesions, which includes an enlarged third ventricle, a vein of Galen aneurysm, an interhemispheric cyst in association with agenesis of the corpus callosum, and a suprasellar arachnoid cyst, should also include a CVIC. Aids in the differential diagnosis are the position of the cystic lesion in relation to the ventricular system and midline structures. The presence of turbulent blood flow within the lesion, as in the vein of Galen aneurysm, will be easily identified by color Doppler imaging. Agenesis of the corpus callosum will usually be associated with other sonographic markers. Prenat Diagn 2003; 23: 779–783.
782
V. H. EISENBERG ET AL.
Anterior
Posterior
Figure 4—Transvaginal sonogram in midsagittal view. CVIC marked by arrowhead
Figure 5—Semiaxial view. CVIC marked by measurement
Figure 6—Axial view. CVIC marked by measurements Copyright 2003 John Wiley & Sons, Ltd.
Hertzberg et al. (1997) described one case of a CVIC, which was diagnosed at 29 weeks’ gestation. The initial presentation was progressive dilatation of the lateral ventricle, finally reaching 17.2 mm at 37 weeks’ gestation, and an ovoid midline cyst, which was initially seen at 29 weeks and progressively enlarged. There were no associated anomalies other than attenuated fetal growth. After delivery, CT and MRI confirmed the cystic lesion to be in the cistern of the velum interpositum, obstructing the foramen of Monro, thus causing the hydrocephalus. The rest of the brain anatomy was normal. The infant was initially neurologically normal but became increasingly irritable over time. A followup CT demonstrated worsening hydrocephalus; ventriculoperitoneal shunting was performed, and the infant was reported to attain normal developmental milestones following this. Vergani et al. (1999) reviewed their experience with 19 cases of interhemispheric supratentorial hypoechoic cystlike lesions without parenchymal involvement, over a period of 8 years in order to establish prenatal diagnostic criteria. Of the 19 cases that were reviewed, 12 cases were lesions related to physiologic midline structures; 7 of these involved the velum interpositum. Of the seven fetuses with CVIC, in six the lesion remained stable and in one it resolved. The median cyst diameter was 10 mm (range 10–30 mm). There were no additional overt abnormalities, other than borderline ventriculomegaly in two fetuses. Pediatric follow-up showed normal neurodevelopmental outcome in all cases (3–84 months). Of the 19 reviewed cases, there were 7 cases of lesions, which were considered pathologic. These cystic lesions were significantly larger (median 40 mm, range 10–80 mm) and progressively increased in size at serial prenatal examinations. The lesions were more likely to be multiple and to be associated with other abnormal findings. Partial or total agenesis of the corpus callosum and overt hydrocephalus were diagnosed prenatally in five of the seven cases that had pathologic cystlike lesions and in none of the 12 cases in which the cystic lesions were related to physiologic structures. Among the five live-born infants with pathologic cysts, two had severe mental and motor delays, whereas the others had normal development following shunt placement. Median age at diagnosis was similar in both groups. The authors conclude that cystlike lesions related to physiologic median structures, such as the CVIC, may be considered variants of normal physiologic structures. We described two cases of cysts of the velum interpositum, representing part of the spectrum of physiologic cysts in median structures. In both cases, the fetal brain anatomy was otherwise normal and the outcome to date was favorable. Table 1 is a summary of cases reported in the literature and of both our cases. The differential diagnosis of midline intracranial cystic lesions is indeed a diagnostic challenge. The cyst diameter, location, progressive change in size, and the presence of associated intracranial anomalies are important parameters in differential diagnosis and parental counseling. Pathologic lesions are more likely to be Prenat Diagn 2003; 23: 779–783.
783
PRENATAL DIAGNOSIS OF CAVUM VELUM INTERPOSITUM
Table 1—Cysts of the velum interpositum diagnosed prenatally
Cases
GA (weeks)
Cyst size (mm)
Associated anomalies
MRI
Outcome
Follow-up
Reference
1 2 3 4 5 6 7 8 9 10
29 19 23 27 30 30 33 34 19 24
NG 15 10 10 10 12 30 10 8 6
Hydrocephalus IUGR Mild ventriculomegaly Mild ventriculomegaly CPC None None None None None None
Postnatal FC NG NG NG NG NG NG NG Fetal FC Fetal FC
VP shunt Stable Stable Stable Stable Resolved Stable Stable DF/U Stable
Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal
Hertzberg et al., 1997 Vergani et al., 1999 Vergani et al., 1999 Vergani et al., 1999 Vergani et al., 1999 Vergani et al., 1999 Vergani et al., 1999 Vergani et al., 1999 Present Present
2 years 9 months 9 months 1 year 6.7 years 5.5 years 1.5 years 5 years 2 years 6 months
GA, Gestational age at diagnosis; NG, not given; VP, ventriculoperitoneal; CPC, choroid plexus cyst; IUGR, intrauterine growth restriction; FC, findings confirmed; DF/U, decreased during follow-up.
larger, to be multiple, to progress in utero, and to be associated with other findings, such as hydrocephalus or agenesis of the corpus callosum. Parents should be counseled that neurodevelopmental delay is possible and even likely in such lesions, and that ventriculoperitoneal shunting may be necessary. A CVIC, however, because of its location, surrounded by the cerebral ventricles, is usually not associated with compression or damage to parenchymal structures (Vergani et al., 1999). These lesions may remain stable or even resolve in utero without any neurodevelopmental sequela. Large lesions, which progress in utero, can be associated with detrimental neurological outcome in the infant or child (Hertzberg et al., 1997). After prenatal diagnosis has been made, the pregnancy should be monitored for changes in cyst size or appearance of associated findings, such as hydrocephalus. Fetal MRI should be performed to aid in ruling out other anomalies. In conclusion, prenatal differential diagnosis of midline cysts demands a careful and thorough search for associated anomalies, correct assessment of cyst location with respect to surrounding structures, measurement of cyst size, and a search for additional cysts. Our experience concurs with previous reports that an isolated CVIC, which remains stable in utero, can be considered to be a finding that carries no detrimental clinical significance.
Copyright 2003 John Wiley & Sons, Ltd.
REFERENCES Berne AS, Lourie H. 1966. Hemorrhage into cistern of velum interpositum in infants. Acta Radiol Diagn 5: 635–643. Chen CY, Chen FH, Lee CC, Lee KW, Hsiao HS. 1998. Sonographic characteristics of the cavum velum interpositum. AJNR Am J Neuroradiol 19: 1631–1635. Gangemi M, Donati P, Maiuri F, Sigona L. 1997. Cyst of the velum interpositum treated by endoscopic fenestration. Surg Neurol 47: 134–136; discussion 136–137. Hassan J, Sepulveda W, Teixeira J, Cox PM. 1996. Glioependymal and arachnoid cysts: Unusual causes of early ventriculomegaly in utero. Prenat Diagn 16: 729–733. Hertzberg BS, Kliewer MA, Provenzale JM. 1997. Cyst of the velum interpositum: antenatal ultrasonographic features and differential diagnosis. J Ultrasound Med 16: 767–770. Lees RF, Harrison RB, Teates D, et al. 1978. Ultrasonic demonstration of a cyst of the velum interpositum. South Med J 71: 401–402. Lunsford LD, Maroon JC, Bank WO. 1977. Localization of velum interpositum AVM with metrizamide ventriculography and simultaneous stereoangiography. J Neurosurg 47: 623–625. Mallucci CL, Obukhov S. 1995. Successful removal of large pineal region meningiomas: two case reports. Surg Neurol 44: 562–566. Meller W, Tsai LY, Chiu LC. 1985. Cavum velum interpositum in a boy with infantile autism. J Autism Dev Disord 15: 109–111. Sahinoglu Z, Uludogan M, Delikara MN. 2002. Prenatal sonographic diagnosis of dilated cavum vergae. J Clin Ultrasound 30: 378–383. Spiegel SM, Nixon B, TerBrugge K, et al. 1988. Arachnoid cyst of the velum interpositum. AJNR 9: 981–983. Vergani P, Locatelli A, Piccoli MG, et al. 1999. Ultrasonographic differential diagnosis of fetal intracranial interhemispheric cysts. Am J Obstet Gynecol 180: 423–428.
Prenat Diagn 2003; 23: 779–783.
