Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 49, Num. 4, 2003, pp. 350-351

Journal of Postgraduate Medicine, Vol. 49, No. 4, Oct-Dec, 2003, pp. 350-351

Images in Radiology

Vein of Galen Aneurysmal Malformation: Antenatal MRI

Maheshwari PR, Pungavkar SA, Narkhede P, Patkar DP

Department of Radiology, K.E.M Hospital, Acharya Dhonde Marg,Parel, Mumbai - 400012
Correspondence Address: Department of Radiology, King Edward Memorial Hospital, Parel, Mumbai - 400012 praveenparikshitdas@rediffmail.com

Code Number: jp03097

CASE HISTORY

Antenatal ultrasound of a 30-year-old lady at 28 weeks of gestation detected an anechoic, tubular structure in the posterior cranial fossa of the foetus with presence of flow on colour Doppler. The foetus also showed signs of cardiac failure. Aneurysmal malformation of the vein of Galen was suspected.

Multiplanar MRI of the foetus was subsequently performed with GE -Echospeed 1.5 T MR, single shot fast spin echo (ssFSE) sequence, TE of 92, TR of 1370, NEx (no. of excitations) of 0.55, Field of view 38 x 26 cm and matrix 256 x 224. It showed a large S-shaped area of flow void along the course of the vein [Figure-1]. The straight and transverse sinuses were also enlarged [Figure-2]. The diagnosis of vein of Galen malformation was confirmed. There was no hyperintense signal within these dilated structures to suggest thrombosis. The rest of the brain parenchyma and ventricles were normal. No other abnormal tortuous vessels were found. MR venography was not done as the patient could not cooperate further.

Pregnancy continued uneventfully and the child was born at 35 weeks' gestation. Post-natal digital subtraction angiography [DSA] corroborated the findings [Figure-3]. Glue embolisation was subsequently done, with successful obliteration of the malformation. However, the child died at 29 hours of age from intractable congestive heart failure.

DISCUSSION

Vein of Galen aneurysmal malformations (VGAM) are rare congenital vascular malformations characterised by shunting of the arterial flow into an enlarged cerebral vein dorsal to the tectum. Most of these malformations present in early childhood, often causing congestive heart failure in the neonate.[1]

VGAM is defined as an aneurysmal dilatation of the vein of Galen, with arterial input from one or more major intracranial arteries, either directly or via an interposed angiomatous malformation.[2] Arteriovenous malformations arise when fistulas develop in positions where primitive vessels cross in the embryo, which is most prominent near the choroid plexus. Fistula formation in the deep midline region, therefore, results in a malformation consisting predominantly of the choroidal vessels drained by the deep venous system, of which the vein of Galen is the main channel.[2]

Although VGAMs constitute only 1% of all cerebral vascular malformations, they comprise up to 30% of all paediatric vascular malformations.[3] VGAM develops between the 6th and the 11th week of gestation, after the development of the circle of Willis. Other venous anomalies such as anomalous dural sinuses and sinus stenoses are commonly present in association with VGAM.[1] A fully developed vein of Galen malformation may vary considerably in complexity from an aneurysmal dilatation fed by the branches of posterior choroidal or posterior cerebral vessels, to an extremely complex malformation fed by all major intracranial vessels.[2] Antenatal MRI can show the malformation in three dimensions and depict the exact anatomy of the dilated channels and thrombosis if any. Magnetic resonance angiography (MRA) with 2D-TOF may be a useful additional technique for evaluating foetal VGAM.[4] Embolisation of the feeding arteries is the preferred therapeutic modality for a patient with severe cardiac failure.[3] MRI is mandatory before endoarterial treatment, to assess the brain parenchyma. If there is severe parenchymal damage, endovascular treatment cannot compensate for the irreversible melting-brain process. MRI has a prognostic value, allowing the decision for therapeutic approach. Angiography is mandatory only at the time of endovascular treatment, while MRA and MRI have a role in follow-up.[5]

Antenatal USG and Colour Doppler can make the diagnosis of VGAM; however, MRI can not only make the diagnosis but also evaluate any associated parenchymal damage and thrombosis to a better extent, because of excellent soft-tissue contrast and lack of interference by bony structures. In conclusion, MR imaging and MR angiography can indicate the major vessels of supply, tortuousity of accessible arteries, venous anatomy, and parenchymal / ventricular status even antenatally and aid in the management and follow-up of such lesions.

REFERENCES

1.	Jones BV, Ball WS, Tomsick TA, Millard J, Crone KR. Vein of Galen aneurysmal malformation: diagnosis and treatment of 13 children with extended clinical follow-up. AJNR Am J Neuroradiol 2002;23:1717-24.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]
2.	Johnston IH, Whittle IR, Besser M, Morgan MK. Vein of Galen Malformation: Diagnosis and Management. Neurosurgery 1987;20:747-58.  Back to cited text no. 2  [PUBMED]
3.	Kothari SS, Naik N, Juneja R, Saxena A. Aneurysm of the Vein of Galen in neonates: Report of Four Cases. Ind Heart J 2001;53:499-502.  Back to cited text no. 3
4.	Kurihara N, Tokieda K, Ikeda K, Mori K, et al. Prenatal MR findings in a case of aneurysm of the vein of Galen. Pediatr Radiol 2001;31:160-2.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.	Campi A, Rodesch G, Scotti G, Lasjaunias P. Aneurysmal malformation of the vein of Galen in three patients: clinical and radiological follow-up. Neuroradiology 1998; 40:816-21.  Back to cited text no. 5

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