Address correspondence to Vincenzo Suma, MD, Ultrasonic Service, Dept. of Obstetrics & Gynecology, Ospedale Civile, 35100, Padua, Italy. Ph: 39498213481, Fax: 39498213502

Synonyms: Ectasia or varix of the vein of Galen. BDE: CNS arteriovenous malformation.

Definition: Rare arteriovenous malformation of the central nervous system characterized by a high venous flow.

Types: 1) arteriovenous fistula, 2) arteriovenous malformation with ectasia of the vein of Galen and 3) varix of the vein of Galen1, 2.

Prevalence: Less than 200 cases have been reported.

Etiology: Unknown.

Pathogenesis: Arteriovenous fistula from immaturity of the cerebral vascular system with persistence of fetal vessel.

Embryology: The malformation starts about 712 weeks, when the median prosencephalic vein drains the large choroid plexuses.

Diagnosis: Midline cystic mass in the pineal region of the brain with high velocity flow on Doppler examination.

Associated anomalies: Hydrocephalus, non-immune hydrops and porencephaly.

Differential diagnosis: (see table 2)

Prognosis: Poor when hydrops is present.

Recurrence risk: Not increased.

Management: Standard obstetrical care.

MESH Cerebral veins; vein of Galen BDE 0186 ICD9 747.81 CDC 747.810

A 32-year-old primigravida patient was referred for routine ultrasound at 33 weeks of pregnancy. Her history was unremarkable. Two previous ultrasounds, done elsewhere during the 16th and 25th weeks, demonstrated a live singleton fetus without apparent structural abnormalities and with normal morphological development. An examination was done with an ATL Ultramark 5, with pulsed Doppler and convex 5 MHz transducer. It revealed, in the axial section of the cranium, the presence of a welldefined fluidfilled oval structure measuring 24 x 19 mm, located posteriorly above the thalamus. Angling the probe slightly behind the oval mass revealed a tubular anechoic prolongation reaching up to 3 mm from the skull at the inion (fig. 2).

The lateral, third and fourth ventricles appeared normal and no other intracranial abnormalities were present. Pulsed Doppler of the cystic lesion and its elongation throughout all its extension demonstrated a high velocity venous flow (fig. 3).

This type of flow was not seen elsewhere. Ultrasound imaging suggested the possibility of an arteriovenous aneurysm, and the location strongly suggested an aneurysm of the vein of Galen. The diagnostic, prognostic and therapeutic problems were frankly discussed with the parents by a team of obstetricians, echographists, neurosurgeons and pediatricians.

As a precaution, the mother underwent a cesarean section after the 39th week. The male newborn had its umbilical cord around the neck and presented an Apgar index of 7 and 10 at 1 and 5 minutes. The weight was 3,310g, cranial circumference 362 mm (75th percentile.), thorax diameter 330 mm, and the whole length 500 mm. Immediately after the birth, a transfontanellar ultrasound showed an aneurismal sac of 25 x 20mm, behind the splenium of corpus callosum (fig. 4).

A CT scan confirmed a big aneurysm of the vein of Galen, with marked contrast medium enhancement (fig.5). The superior sagittal sinus and the straight sinus together with the torcularis appeared widened.

Hydrocephalus was absent at birth. Echocardiography showed no heart malformations, with normal Doppler, but the righ-tsided structures (atrium, ventricle, and main pulmonary artery) were slightly enlarged. The child had no signs of cardiac decompensation, polypnea, or liver enlargement. These facts and the absence of hypertensive hydrocephalus warranted postponing surgical treatment.

During the following months, the neuroanatomical evolution was monitored with serial transfontanellar echography and CT scans. At 9 months, the baby underwent MRI that permitted further definition of the aneurysm and the whole brain (fig. 6). After his first year, the patient underwent selective angiographies in our hospital and in other centers, with the intent to embolize the aneurysm. The infant is currently alive and well.

Aneurysm of the vein of Galen was first described by Jager in 1937³. Less than 200 postnatal cases had been reported in the literature up to 19844. The use of high resolution echography and pulsed Doppler sonography allowed the first prenatal diagnosis^4-13. There are only 10 prenatal diagnoses of aneurysm of the vein of Galen by ultrasound and/or pulsed Doppler. We have attempted to identify the common features of these situations (Table 1).

Table 1: Review of cases detected prenatally

The denomination of aneurysm of the vein of Galen includes different arteriovenous fistulae located in the vicinity of the midbrain that vary from a single large aneurysmal dilatation of the vein of Galen to multiple communications between the vein and the carotid and vertebrobasilar systems¹⁴. Three types are described: arteriovenous fistula, arteriovenous malformation with ectasia of the vein of Galen and varix of the vein of Galen^1,2. Both the ectasia and the varix appear to present later in life with bleeding episodes and do not present in the neonate with cardiac failure². Rarely, an aneurysm with a single feeder can exist¹⁵. Arteriovenous fistulae associated with a varix are not part of the definition when they are located elsewhere in the brain¹⁶.

According to Padget¹⁷ the primary cerebral vascular plexus becomes arterial and venous vessels between 7 and 9 weeks. The primary arteries and veins of the neural tube rise from distinct capillary plexuses and are made by simple endothelial canal joints forming right angles. It is thought that the Galenic system arises from the choroidal veins and the arteriovenous fistula, that give rise to the aneurysm of the vein of Galen, and should correspond to the dimension and the number of the perpendicular vessels crossings through the primary arteries and veins. The pressure of high flow and turbulent arteriovenous shunt leads to the arterialization of the vein of Galen with concomitant increase of volume and thickness of its walls. Histological studies have shown that the wall of the aneurysm is thickened and may have an irregular muscle coat, suggesting hemodynamic perturbations^{14, 18}. Recent studies have suggested that since angiography may fail to opacify the straight sinus and part of the transverse sinus, the defect probably occurs in the wall of the vein, instead of in the vein^{14, 18}. Also, since some of the feeders may belong to arteries of the velum interpositum and of the ambient cistern, this suggests that the vessel cannot represent the vein of Galen or an internal cerebral vein but a persistent fetal vein: the median prosencephalic vein. This important study therefore places the origin of the abnormality at around the 7th to 12th week period, during which the median prosencephalic vein drains the large choroid plexuses.

A cystic or tubular mass on the midline of brain or in the pineal region with a turbulent venous and/or arterial flow with Doppler signal is typical of the diagnosis. However, when a clot has formed, it may be iso or even hyperechoic¹⁹.

Differential diagnosis with other midline cystic cerebral lesions (table 2) is based on the typical localization of aneurysm of the vein of Galen, the presence of a high blood flow within the "cystic" and the frequent coexistence of hydrocephalus and cardiomegaly.

Arachnoid cysts  are commonly supratentorial and lack flow on Doppler. They appear as thinwalled, fluidfilled cystic masses that usually displace adjacent brain structure^20-22.

Porencephalic cysts are fluidfilled spaces replacing normal brain parenchyma. They do not create any mass effect and often communicate with the lateral ventricles or subarachnoid space.

Choroid plexus cysts are easily discriminated by their location in the choroid plexus. They are identified in the second trimester and usually resolve by the 24th week^23-25, although occasional cysts may resolve later²⁶. They are usually located in the posterior aspect (atria) of the lateral ventricles, and might be uni or bilateral. Rarely, large choroid cysts may expand the ventricular wall. In that case, there seems to be a significantly greater risk of chromosomal abnormality (trisomy 18)²⁷.

Choroid papillomaare characterized by a large, lobulated, highly echogenic mass in the trigone of the lateral ventricle with uniform dilation of the ventricular system and often with an increase in subarachnoid space suggesting communicating hydrocephalus28.

Intracranial teratomas  are generally large tumors that demonstrate a heterogeneous, bizarre appearance29. Deformation of the cranium, hydrocephalus (if the mass obstructs cerebrospinal fluid flow), and a highly disorganized intracranial anatomy suggest the diagnosis of intracranial teratoma.

Table 2: Differential diagnoses of aneurysm of the vein of Galen

Although vein of Galen aneurysms may become symptomatic in the elderly^30-31, they are more typically diagnosed in the neonatal period. In a large recent review³², 80 patients presented as neonates, 82 between 1 and 12 months, 39 between 1 and 5 years and only 44 were over 6 years. The common clinical features in the neonate are cardiomegaly with congestive heart failure^33-34 and increased intracranial pressure with hydrocephaly or cranial bruit35. When the associated intracranial abnormality is not recognized, unnecessary cardiac examinations are performed that delay the diagnosis and treatment36. Focal neurological deficit, seizure1 and hemorrhages are less common findings. In older patients, a variety of symptoms have been reported, that include headache³⁷, visual defect³⁸, syncope, subarachnoid hemorrhage, seizure³⁹, mental retardation⁴⁰ and even psychiatric disorders^{40, 2}.

In analyzing the clinical aspects of aneurysm of the vein of Galen, Amacher in 1973 identified three groups (neonatal, infantile and juvenile) based on the seriousness of the lesion and the age of the patient at the onset of symptoms⁴². The severity of cardiomegaly and cardiac decompensation depends on the size and complexity of the vein of Galen aneurysm. During intrauterine life, the arteriovenous fistula maintains a low flow rate because of the low resistance of placental vascular bed; at delivery the changes of the blood circulation cause a sudden increase of flux through the fistula^43-45. Therefore, if the aneurysm is small (less than 1 mm), the child may be asymptomatic at birth and the aneurysm may cause no relevant consequences for a long period. Later on, during infancy, adolescence or juvenile age, symptoms may occur such as headache, seizure, visual disturbances, due to chronic hydrocephalus and/or subarachnoid or cerebral hemorrhages. On the contrary, with a large aneurysm (greater than 20 mm), the great amount of blood circulating in the highflow fistula induces an overload of the venous circulation that can cause cardiomegaly, decompensation and hydrops. Therefore, an assessment of the cardiovascular system should be performed to identify early signs of cardiac insufficiency, to establish the time and the type of delivery, and to prepare an adequate assistance for the newborn. A careful echographic prenatal examination allows the neurosurgeon to plan the best neuroradiological and surgical management according to the type of vein of Galen aneurysm and the status of the patient.

No data are available indicating the optimal mode of delivery of fetuses with aneurysm of the vein of Galen. If there are other associated anomalies such as severe porencephaly or cardiomegaly with hydrops, aggressive management is not indicated due to the high neonatal mortality (over 90% of neonate). Hydrocephaly may be an indication for elective cesarean section. In the absence of associated anomalies we think that, to avoid possible damage during labor, an elective cesarean section can be performed.

1. Lasjaunias P, Manelfe C, Terbrugge K, et al: Endovascular treatment of cerebral arteriovenous malformations. Neurosurgery 9:26575 Rev 1986.

2. Lasjaunias P, Terbrugge K, Piske R, et al: Dilatation de la veine de Galien. Formes anatomocliniques et traitement endovasculaire a propos de 14 cas explores et/ou traites entre 1983 et 1986. Neurochirurgie 33: 31533, 1986.

3. Jaeger Jr, Forbes RP, Dandy WE: Bilateral congenital cerebral arteriovenous communications aneurysm. Trans Am Neurol Ass 63:1736 1937.

4. Vintzileos AM, Eisenfeld LI, Campbell WA, et al: Prenatal ultrasonic diagnosis of arteriovenous malformation of the vein of Galen. Am J Perinatol 3:209 1986.

5. Rizzo G, Arduini D, Colosimo C Jr, et al: Abnormal fetal cerebral blood flow velocity waveforms as a sign of an aneurysm of the vein of Galen. Fetal Ther 2 (2):759 1987.

6. Mendelson DB, Hertzami Y, Butterworth A: In utero diagnosis of a vein of Galen aneurysm by ultrasound. Neuroradiology 26:4178 1984.

7. Ordorica SA, Marks F, Frieden JF, et al: Aneurysm of the vein of Galen: a new cause for Ballantyne syndrome. Am J Obstet Gynecol 162:11667, 1990.

8. Reiter AA, Hulita JC, Carpenter RJ, et al: Prenatal diagnosis of arteriovenous malformation of the vein of Galen. JCU 14(8): 6238, 1986.

9. Hirsch JH, Cyr D, Eberhardt H, et al: Ultrasonographic diagnosis of an aneurysm of the vein of Galen in utero by duplex scanning. J Ultrasound Med 2:2313, 1983.

10. Mao K, Adams J: Antenatal diagnosis of intracranial arteriovenous fistula by ultrasonography. Case report. Br J Obstet Gynecol 90:872, 1983.

11. Filly AR, Cardoza DJ, Goldstein BR, et al: Detection of fetal central nervous system anomalies: a practical level of effort for a routine sonogram. Radiology 172:4038, 1989.

12. Mizejewsky JG, Polensky S, MondragonTue AF, et al: Combined use of alphafetoprotein and ultrasound in the prenatal diagnosis of arteriovenous fistula in the brain. Obstet Gynecol 70:4523, 1987.

13. Jeanty P, Kepple D, Roussis P, et al: In utero detection of cardiac failure from an aneurysm of the vein of Galen.Am J Obstet Gynecol 163:501, 1990.

14. Ruchox MM, Renjard L, Monegier du Sorbier C, et al: Histopathologie de la veine de Galen. Neurochirurgie 33:27284, 1987.

15. Koh AS, Grundy HO: Fetal heart rate tracing with congenital aneurysm of the great vein of Galen. Am J Perinatol. 5(2): 98100, 1988.

16. Rayboud CA, Hold JK, Strother CM: Aneurysm of the vein of Galen. Angiographic study and morphogenetic considerations. Neurochirurgie 33(4):30214, 1987.

17. Padget DH: The cranial venous system in man in reference to development, adult configuration and relation to the arteries. Am J Anat 98:30755, 1956.

18. Menezes AH, Smith DE, Bell WE: Posterior fossa hemorrhage in the term neonate. Neurosurgery 13:4526, 1983.

19. Carrillo R, Carreira LM, Prada J, et al: Giant aneurysm arising from a single arteriovenous fistula in a child. Case report. J Neurosurg. 60:10858, 1984.

20. Meizner I, Barki Y, Tadmor R, et al: In utero ultrasonic detection of fetal arachnoid cyst. JCU 16:5069, 1968.

21. Diakoumatis EE, WeinbergB, Molin J: Prenatal sonographic diagnosis of a suprasellar arachnoid cyst. J Ultrasound Med 5:52930, 1986.

22. Chilton SJ, Cremin BJ: Ultrasound diagnosis of CSF cystic lesions in the neonatal brain. Br J Radiol 56:61330, 1983.

23. Ostlere S, Irving H, Lilford R: Choroid plexus cysts in the fetus. Lancet 1:1491, 1987.

24. Gabrielli S, Reece AE, Pilu G, et al: The clinical significance of prenatally diagnosed choroid plexus cysts. Am J Obstet Gynecol 160:120729, 1989.

25. Benacerrof B: Asymptomatic cysts of the fetal choroid plexus in the second trimester. J Ultrasound Med 6:4758, 1987.

26. Chitkara U, Cogswell C, Norton K, et al: Choroid plexus cysts in the fetus a benign anatomic variant or pathologic entity? Report of 41 cases and review of the literature. Obstet Gynecol 72:1859, 1988.

27. Bundy A, Saltzman D, Prober B, et al: Antenatal sonographic findings in trisomy 18. J Ultrasound Med 5:3614 1986.

28. Cappe PI, Lam HA: Ultrasound in the diagnosis of choroid plexus papilloma. JCU 13:1213, 1985.

29. Lipman S, Pretorius D, Rumack C, et al: Fetal intracranial teratomas US diagnosis of three cases and a review of the literature. Radiology 157:4914, 1985.

30. Rosenfeld JV, Fabinyi GC: Acute hydrocephalus in an elderly woman with an aneurysm of the vein of Galen. Neurosurgery. 15(6): 8524, 1984.

31. Mayberg MR, Zimmerman C: Vein of Galen Aneurysm associated with dural AVM and straight

sinus thrombosis. Case report. J Neurosurg. 68(2): 28891, 1988.

32. Johnston IH, Whittle IR, Besser M et al: Vein of Galen malformation: diagnosis and management. Neurosurgery. 20(5): 74758, 1987.

33. Schwechheimer K, Kuhl G: Arteriovenous angioma of the vein of Galen causing cardiac failure in the neonate. Report on clinical and pathological findings in two cases. Neuropediatrics 14(3): 1847, 1983.

34. Stanbridge R de L, Westaby S, Smallhorn J, et al: Intracranial arteriovenous malformation with neurysm of the vein of Galen as cause of heart failure in infancy. Echocardiographic diagnosis and results of treatment. Br Heart J 49(2): 15762, 1983.

35. Marasini M, Ribaldone D, Panizzon G, et al: Grave insufficienza cardiaca neonatale da fistola artero venosa della vena di Galeno. Considerazioni emodinamiche a proposito di 3 casi clinici. G Ital Cardiol. 14(9): 6717, 1984.

36. Ronderos MA, Herraiz Sarachaga JI, Barrio Corrales FR, et al: Fistula arteriovenosa cerebral como causa de insuficiencia cardiaca neonatal. Presentacion de tres casos. An Esp Pediatr 25(1): 57 621, 1986.

37. Pun KK, Yu YL, Huang CY, et al: Ventriculo peritoneal shunting of acute hydrocephalus in vein of Galen malformation. Clin Exp Neurol 23: 209 12, 1987.

38. Wilkins RH: Natural history of intracranial vascular malformations: a review. Neurosurgery 16(3): 42130, 1985.

39. Phillips SJ, Dooley JM, Camfield PR: Vein of Galen malformation with cerebral calcification: a reversible cause of neurodegenerative disease. Can J Neurol Sci 13(2): 1036, 1986.

40. Remington G, Jeffries JJ: The role of cerebral arteriovenous malformations in psychiatric disturbances: case report. J Clin Psychiatry 45(5): 2269, 1984.

41. Aleem A, Knesevich MA: Schizophrenia like psychosis associated with vein of Galen malformation: a case report. Can J Psychiatry 32(3): 2267, 1987.

42. Amacher AL, Shillito J Jr: The syndromes and surgical treatment of aneurysm of the great vein of Galen. J Neurosurg 39:8998, 1973.

43. Kempe L: Venous aneurism and dural venous malformation In: Kappa JP, Schmidek HH: The cerebral venous system and its disorders. Grune and Stratton Inc., New York, 1984.

44. Schwecheimrk, Kuhl G: Arteriovenous angioma of the vein of Galen causing cardiac failure in the neonate. Neuropediatrics 14, 184, 1983.

45. Crippa, Taborelli A, Ballarini V, et al: L"aneurisma della vena di Galeno descrizione di un caso ad esordio in epoca neonatale. Neurologica 1:6975, 1987.