Enlargement of the vein of Galen

Ectasia or varix of the vein of Galen.

Vein of Galen aneurysm, pial arterovenous malformation, cerebral arterovenous malformation

Enlargement of the vein of Galen is usually the consequence of cerebral artero-venous malformations draining into the deep cerebral veins.

ICD-10: Q 28.2

Enlargement of the vein of Galen during fetal life has been described with two different types of arterovenous malformation: vein of Galen aneurysmal malformation (VGAM) and or pial arterovenous malformation (pial AVM) . In the pediatric literature the two malformations have almost the same frequency.¹ In the prenatal literature VGAM are predomininant with only a handful of cases of pial AVM described thus far.² However, it is likely that a precise differentiation between the two entities was not made in all cases. VGAM includes a spectrum of artero-venous malformations in proximity of the midbrain, ranging from a single large dilatation of the vein of Galen to multiple communications between the vein and the carotid and vertebrobasilar systems.³ Although a continuum of lesions is encountered, three types are commonly distinguished: (1) arterovenous fistula, (2) arteriovenous malformation with ectasia of the vein of Galen and (3) varix of the vein of Galen.^{1, 4} The main difference among these types lies in the number and size of the feeding arteries. The arterovenous fistula is characterized by a maze of large feeding arteries leading to overflow to the cerebral veins and shunting of the brain parenchyma. This may result in high-output cardiac failure and brain damage as a consequence of ischemia and hemorrahe. It is frequently manifest in the fetal and neonatal period with cardiac failure. Both the ectasia and the varix are associated with less shunting arteries and tend to present later in life with bleeding episodes and are not associated with cardiac failure.^{1, 4} The enlarged vein or Galen drains into the dural sinuses either through the straight sinus and the torcular Herophili or, more frequently through a falcine sinus, an embryonic venous channel that connects to the superior sagittal sinus and usually undergoes obliteration in normal foetuses. Pial AVM are intraparenchymal arterovenous malformations occurring within the cerebral parenchyma, most frequently in the supratentorial space. They are usually fed by pial (cortical arteries) and drain into the deep cerebral veins resulting in variable dilatation of the vein of Galen and dural sinuses.. The hemodynamic and cerebral consequences depend upon the size of the arterovenous malformation ans are similar to those encountered with the arterovenous fistula type of VGAM.^{1, 2, 5}

Brain damage as the consequence of arterial blood stealing by the abnormal arterovenous collections in the form of ventriculomegaly, destructive lesions, hemorrage and hydrops are frequently encountered in cases diagnosed antenatally.

The etiology of the vein of Galen aneurysm is unknown.

Not known to be increased.

The most prominent finding of both VGAM and pial AVM is the enlargement of the vein of Galen, that appears on two-dimensional ultrasound as an elongated anechoic area in the posterior part of the midline. Rarely, a thrombus may develop within the enlarged vein of Galen and this appears as an echogenic area.⁶ Color and pulsed Doppler demonstrate turbulent and pulsatile venous blood flow within the enlarged vein of Galen.^7-11In VGAM with an arteriovenous fistula the arterial feeding vessels connecting the arteries of the base of skull with the large vein of Galen may be seen.^7-11 A specific diagnosis of pial AVM is possible by demonstrating the presence of an abnormal arteriovenous network within the brain parenchyma that connects with the enlarged vein of Galen.^{2, 5} The dural sinuses and the neck vessels may be enlarged as well, and it is frequently possible to demonstrate the presence fo the falcine sinus connecting the vein of Galen to the superior sagittal sinus. The cerebral architecture may be intact, or it may be distorted because of the concomitance of edema, ventriculomegaly, hemorrage, porencephaly. Signs of cardiac overload may be present, including cardiomegaly, polyhydramnios, and hydrops. Three dimensional sonography has been used to better demonstrate the abnormal vascular architecture of the lesion^12-15, and Magnetic resonance is commonly utilized, to assess both the vascular malformation and the integrity of the cerebral structures.^{2, 5, 7, 8, 16}

On two-dimensional ultrasound it may be impossible to differentiate enlargement of the vein of Galen from an intracranial cyst. A specific diagnosis is easily made by using Color and/or pulsed Doppler.

Enlargement of the vein of Galen is associated with anomalies that have a variable prognosis, spanning from a completely normal outcome to neonatal death. Visualization of the abnormal vascular network is of value, as the presence of large arterial vessels feeding the lesion is worrysome. However, there are no clear thresholds to evaluate the complexity of the arteriovenous malformation. The most valuable antenatal prognostic factors stressed in most studies include the demonstration of signs of cardiac overload (cardiomegaly, hydrops) and brain damage.⁸

Large vein of Galen aneurysms would be probably identified by a standard sonographic examination. However, most of the cases diagnosed in utero thus far have been recognized in the third trimester. A progressive growth in size of the vascular lesions is documented, and sonographic findings may not be conspicuous in early gestation. We have had experience with paucisymptomatic VGAM with unremarkable sonograms both in the second and third trimester.

Although vein of Galen enlargament may become symptomatic in the elderly¹⁷, it is more frequently seen in the neonatal period.^{1, 4, 18, 19} In a review of VGAM, 39% were diagnosed in the neonatal period neonates, 33% between 1 and 12 months, 15% between 1 and 5 years and 18% over 6 years.²⁰ The common clinical features in neonates are congestive heart failure and increased intracranial pressure with hydrocephaly or cranial bruit.²¹ Focal neurological deficit, seizure and hemorrhages are less common findings. In older patients, a variety of symptoms have been reported²¹, that include headache, visual defect, syncope, subarachnoid hemorrhage, seizure, mental retardationand even psychiatric disorders.²²

There is a controversy in the literature with regard to the outcome of VGAM and pial AVM between pediatric series and prenatal series. Intrauterine selection and early neonatal death of the most severe cases probably account for the discrepancy. Pediatric data do suggest that these lesion can be treated successfully in most cases. In one of the largest available series coming from one single center, the operative mortality of VGAM was 10%, and 74% of survivors were neurologically normal. Pial AVM have a similar outcome with a mortality rate of 10-15% and normal neurologic development in about 80% of survivors. ^{23, 24} The prenatal literature has been extensively reviewed.⁸ The overall mortality rate was 54% and only 44% of survivors had a normal development. The outcome however is strongly dependent upon the antenatal evidence of other intracranial abnomalities (ventriculomegasly, destructive lesions) and/or hydrops. When any of these was found, the prognosis was always poor. Conversely, when these were not present, most (although not all) infants survived in good conditions.8 It may be difficult however to predict the final outcome of lesions seen in early gestation as hydrops and brain injury usually develop in the third trimester.

The prognosis is poor when intracranial abnormalities and/or hydrops are present, and a conservative management is reccomended. Fetuses with isolated enlargement of the vein of Galen, either as a consequence of VGAM or pial AVM can be treated after birth with good results. Serial scans to monitor the cardiovascular conditions of the fetus and identify early signs of hydrops are recommended. Colour Doppler mapping of the vessels feeding the lesion is possible, and we expect that it may help in identifying the cases with a higher probability of successful treatment. Delivery should occur at term but there are no available data on the optimal mode. Vaginal delivery is not contraindicated.

1. Ozanne A, Alvarez H, Krings T, Lasjaunias P. [Pediatric neurovascular malformations: vein of Galen arteriovenous malformations (VGAM), pial arteriovenous malformations (pial AVM), dural sinus malformations (DSM)]. Journal of neuroradiology Journal de neuroradiologie. 2007;34(3):145-66. Epub 2007/07/03. Pathologie neurovasculaire malformative de l'enfant: malformations anevrismales de la veine de Galien (MAVG), malformations arterioveineuses piales (MAVP), malformations des sinus duraux (MSD).

2. Garel C, Azarian M, Lasjaunias P, Luton D. Pial arteriovenous fistulas: dilemmas in prenatal diagnosis, counseling and postnatal treatment. Report of three cases. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2005;26(3):293-6. Epub 2005/07/30.

3. Raybaud CA, Strother CM, Hald JK. Aneurysms of the vein of Galen: embryonic considerations and anatomical features relating to the pathogenesis of the malformation. Neuroradiology. 1989;31(2):109-28. Epub 1989/01/01.

4. Lasjaunias P, Terbrugge K, Piske R, Lopez Ibor L, Manelfe C. [Dilatation of the vein of Galen. Anatomoclinical forms and endovascular treatment apropos of 14 cases explored and/or treated between 1983 and 1986]. Neuro-Chirurgie. 1987;33(4):315-33. Epub 1987/01/01. Dilatation de la veine de Galien. Formes anatomo-cliniques et traitement endovasculaire a propos de 14 cas explores et/ou traites entre 1983 et 1986.

5. Koroglu M, Cil B, Yesildag A, Baykal B, Cekirge S, Oyar O. Prenatal diagnosis of intracranial pial arteriovenous fistula and endovascular treatment during the neonatal period. Diagn Interv Radiol. 2006;12(2):64-7. Epub 2006/06/06.

6. Vijayaraghavan SB, Vijay S, Kala MR, Neha D. Prenatal diagnosis of thrombosed aneurysm of vein of Galen. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2006;27(1):81-3. Epub 2005/12/01.

7. Brunelle F. Brain vascular malformations in the fetus: diagnosis and prognosis. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery. 2003;19(7-8):524-8. Epub 2003/08/16.

8. Deloison B, Chalouhi G, Sonigo P, Zerah M, Millisher-Bellaiche A, Dumez Y, Brunelle F, Ville Y, Salomon L. The hidden mortality of vein of galen aneurysmal malformation: retrospective study and review of the literature. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2012. Epub 2012/05/19.

9. Pilu G, Falco P, Perolo A, Sandri F, Cocchi G, Ancora G, Bovicelli L. Differential diagnosis and outcome of fetal intracranial hypoechoic lesions: report of 21 cases. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 1997;9(4):229-36. Epub 1997/04/01.

10. Sepulveda W, Platt CC, Fisk NM. Prenatal diagnosis of cerebral arteriovenous malformation using color Doppler ultrasonography: case report and review of the literature. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 1995;6(4):282-6. Epub 1995/10/01.

11. Paternoster DM, Manganelli F, Moroder W, Nicolini U. Prenatal diagnosis of vein of Galen aneurysmal malformations. Fetal diagnosis and therapy. 2003;18(6):408-11. Epub 2003/10/18.

12. Heling KS, Chaoui R, Bollmann R. Prenatal depiction of the angioarchitecture of an aneurysm of the vein of Galen with three-dimensional color power angiography. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Utrasound in Obstetrics and Gynecology. 2000;15(4):345. Epub 2000/07/15.

13. Heling KS, Chaoui R, Bollmann R. Prenatal diagnosis of an aneurysm of the vein of Galen with three-dimensional color power angiography. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2000;15(4):333-6. Epub 2000/07/15.

14. Lee TH, Shih JC, Peng SS, Lee CN, Shyu MK, Hsieh FJ. Prenatal depiction of angioarchitecture of an aneurysm of the vein of Galen with three-dimensional color power angiography. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2000;15(4):337-40. Epub 2000/07/15.

15. Sepulveda W, Vanderheyden T, Pather J, Pasquini L. Vein of galen malformation: prenatal evaluation with three-dimensional power Doppler angiography. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 2003;22(12):1395-8. Epub 2003/12/20.

16. Kurihara N, Tokieda K, Ikeda K, Mori K, Hokuto I, Nishimura O, Ishimoto H, Yuasa Y. Prenatal MR findings in a case of aneurysm of the vein of Galen. Pediatric radiology. 2001;31(3):160-2. Epub 2001/04/12.

17. Muquit S, Shah M, Bassi S. Vein of Galen malformation presenting in adulthood. British journal of neurosurgery. 2008;22(5):692-4. Epub 2008/07/29.

18. Lasjaunias P, Manelfe C, Terbrugge K, Lopez Ibor L. Endovascular treatment of cerebral arteriovenous malformations. Neurosurgical review. 1986;9(4):265-75. Epub 1986/01/01.

19. Lasjaunias P, Wuppalapati S, Alvarez H, Rodesch G, Ozanne A. Intracranial aneurysms in children aged under 15 years: review of 59 consecutive children with 75 aneurysms. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery. 2005;21(6):437-50. Epub 2005/04/19.

20. Johnston IH, Whittle IR, Besser M, Morgan MK. Vein of Galen malformation: diagnosis and management. Neurosurgery. 1987;20(5):747-58. Epub 1987/05/01.

21. Wilkins RH. Natural history of intracranial vascular malformations: a review. Neurosurgery. 1985;16(3):421-30. Epub 1985/03/01.

22. Remington G, Jeffries JJ. The role of cerebral arteriovenous malformations in psychiatric disturbances: case report. The Journal of clinical psychiatry. 1984;45(5):226-9. Epub 1984/05/01.

23. Weon YC, Yoshida Y, Sachet M, Mahadevan J, Alvarez H, Rodesch G, Lasjaunias P. Supratentorial cerebral arteriovenous fistulas (AVFs) in children: review of 41 cases with 63 non choroidal single-hole AVFs. Acta neurochirurgica. 2005;147(1):17-31; discussion Epub 2004/12/23.

24. Yoshida Y, Weon YC, Sachet M, Mahadevan J, Alvarez H, Rodesch G, Lasjaunias P. Posterior cranial fossa single-hole arteriovenous fistulae in children: 14 consecutive cases. Neuroradiology. 2004;46(6):474-81. Epub 2004/05/14.

Pilu, G, Buyukkurt S: Vein of Galen enlargement. Visual Encyclopedia of Ultrasound in Obstetrics and Gynecology, www.visuog.org, (December 2012).

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