Endovascular management of vein of galen aneurysm malformation: A series of two case reports.

Vein of Galen Aneurysm malformation is one of the most difficult intracranial vascular lesions to manage. The difficulty in management of its shunts is aggravated by the hemodynamic effect and shunting reflected in the growing brain of infants and children. At present, the therapeutic options are widened by the opening of a new horizon in Intervention Neuroradiology. We present a series of two case reports of these malformations treated using the endovascular method, at our institution.

Introduction

Vein of galen aneurismal malformation (VOGAM) is a rare congenital anomaly with a reported incidence of 30% of pediatric malformations.[12] Jaeger et al., first published a reported case of VOGAM in literature.[3]

In the choroidal stage of development of the cerebral vascular system,[4] the venous drainage is mainly by the median venous structure, the MProsV of Markowski.[5] This median vein of prosencephalon usually involutes as the internal cerebral vein develops. The posterior segment of the MProsV persists as the vein of Galen.

Vein of galen aneurismal malformation is a cluster of arteriovenous fistulas (AVFs) draining into the dilated median vein of the prosencephalon. The arterial feeders are usually from the anterior and posterior choroidal arteries, the pericallosal artery, and the transmesencephalic branches of the basilar tip. The VOGAM is mainly divided into mural and choroidal types. In the mural type (simple type), there is a direct high flow shunt located within the wall. In the choroidal type (complex type), there is interposition of the arterial feeders and the venous aneurysm. Clinically, the mural types of VOGAM present later in infants with macrocephaly or failure to thrive and may be associated with mild cardiac failure or asymptomatic cardiomegaly. The choroidal types of VOGAM usually cause heart failure in newborns.

Pathophysiology

On account of a sustained increased flow, enlarged arteries can be associated with aneurysms or occlusions. On the venous side, there is re-routing of the venous flow into the cortical veins. Impairment of the outflow causes increased venous hypertension and increases the risk of intracranial hemorrhage. Communicating hydrocephalus occurs due to impaired absorption of the cerebrospinal fluid by the arachnoid villi.

Case Reports

Case 1

An 11-month-old male child presented with macrocrania. Antenatal scans in the third trimester revealed vein of galen aneurysmal malformation. Eventually the child was followed up with serial imaging. Computed tomography (CT) and magnetic resonance (MR) imaging [Figure 1] done at the time of presentation showed the VOGAM in the posterior interhemispheric fissure, causing a compression of the third ventricle and the cerebral aqueduct, leading to hydrocephalus. Subsequently, an angiogram was done, which revealed a mural type of VOGAM [Figure 2a, b].

Figure 1

Contrast-enhanced MR images showing the vein of galen aneurysm in the midline causing compression of the third ventricle, leading to hydrocephalus

Figure 2

Pre-embolization vertebral artery angiogram of the anteroposterior and lateral views (a,b), demonstrating the mural type of fistula (arrow), Post embolization vertebral artery angiogram (c,d) shows complete obliteration of the fistula with good visualization of the posterior cerebral artery (arrow)

Procedure: Under general anesthesia, using the retrograde Seldinger technique, right femoral access was taken. Using a 5F envoy guiding catheter, the right posterior cerebral artery (PCA) was selectively catheterized with a micro catheter and micro wire combination (Excel14 / Transcend wire) and the fistula was occluded, with 80% N-butyl cyanoacrylate (NBCA). A post-procedure angiogram revealed complete occlusion of the fistula and better visualization of the PCA branches [Figure 2c, d].

The child had an uneventful course in the ward. On the follow-up of three months, six months, and one year there was decrease in the macrocrania. On the two-year follow-up there was significant decrease in the macrocrania, with normal developmental milestones for age.

Case 2

A 15-month-old female child presented with abnormally dilated neck veins and delayed milestones.

A diagnostic angiogram revealed a choroidal type of VOGAM. Numerous arterial feeders were seen from the bilateral posterior choroidal arteries [Figure 3a, b, c]. In order to reduce the risk of contrast and fluid overload, and to prevent the occurrence of hyperperfusion breakthrough, endovascular treatment in multiple sessions was planned. In the first session, the right posterior choroidal feeders were embolized with 33 and 24% NBCA causing 25% flow reduction in the fistulous connection. The child was asked to come for follow-up after three months. At the age of 18 months, a second session of embolization of the left posterior choroidal feeders was done using 33 and 25% NBCA resulting in 50% reduction in the flow [Figure 4a, b]. The child tolerated the procedure well and was followed up after a three-month interval.

Figure 3

Digital substraction angiogram showing multiple feeders from the posterior choroidal arteries (arrows) in the choroidal type of VOGAM (a,b), with venous drainage into a large ectatic vein (c)

Figure 4

Vertebral angiogram demonstrating reduction in the flow to the malformation after the third session of embolization by NBCA (arrow) (a, b). Further reduction in the flow following the fifth session of embolization (c,d)

At the age of 21 months a third session of embolization was done. The right posterior choroidal feeder was accessed and embolized with 25% NBCA. On a post-procedure angiogram there was 60% reduction in the abnormal flow through the VOGAM. On account of the contrast dose limitation, the procedure was terminated at this stage. The child was taken up for the fourth session after an 11-day interval and embolization of the residual thalamoperforators and posterior choroidal feeders was done with 25% NBCA with 70% decrease in the flow to the VOGAM. The child tolerated the session well and was followed up after a two-month interval. The child was taken up for the fifth session, and embolization of the residual feeders was done [Figure 4c, d]. There was 85% reduction of the flow to the VOGAM. The child was doing well, with clinical improvement in the symptoms and normal developmental milestones for the age, on a follow-up of two years. The child is being followed up regularly with us, to date.

Discussion

Recent advances in the field of intervention neuroradiology has changed the treatment and prognosis of children with VOGAM.[5-8] Therapeutic options available for a VOGAM include no treatment, open surgery, endovascular treatment, and stereotactic radiosurgery. The therapeutic options should be individualized with consideration of age, clinical manifestation of the lesion and the angioarchitecture. In the past, surgery was done for VOGAM, which offered little improvement and fatal outcomes.[910] Endovascular treatment has improved the results of treatment in recent years. The transarterial approach is preferred and more effective in controlling the symptoms of VOGAM.[7] NBCA is the embolic agent used which is premixed with lipiodol (to increase the radio opacity)

In our first case, which was a mural type of fistula, we used high concentrated glue, which was fast setting and highly effective in the high flow variety. In our second case, staged embolization is done, to reduce the risk of fluid overload and prevent the perfusion breakthrough. In this child 33 and 25% NBCA was used for better penetration in the choroidal feeders. NBCA allowed precise targeting of the AV shunt and was preferred over other embolic agents like microcoils.[11]

The presence of pre-existing brain damage characterized by severe atrophy and parenchymal calcifications indicated a poor prognosis, with bad outcomes[12] The transvenous approach was described in literature, but it was associated with increased risks of bleeding complications.[1213] Lasjunias et al., described the largest cohort study of these lesions treated using the endovascular method, at their center, in a period of 11 years, with variable outcomes.[14]

Introduction of endovascular techniques modified the prognosis in patients with VOGAM. With the recent advances of technology of endovascular management, these children can be well-managed with a fairly good outcome.

Conclusion

We presented two cases of vein of galen aneurysms. The treatment plan was individualized with consideration to the clinical manifestations and angioarchitecture of the lesion. The goal of the treatment was clinical improvement of the patients presenting with the symptoms and not an angiographic cure. Endovascular treatment was proven as an effective method of treatment with acceptable risk.