Post-delivery evaluation of morphological change in vein of galen aneurysmal malformation – possible parameter of long-term prognosis

Introduction

Vein of Galen aneurysmal malformation (VGAM) is a rare congenital vascular malformation of the central nervous system. It is often accompanied by severe neonatal congestive heart failure, followed by multiple organ failure and death. Although recent advances in the medical treatment have resulted in reduced mortality and morbidity, the long-term neurodevelopmental prognosis is not well described.

We hypothesize that the postnatal morphological changes of aneurysms can be associated with cerebral circulatory disturbance. This is the first case report evaluating morphological changes in VGAM when the exacerbation of heart failure occurred after birth.

Case report

A pregnant woman was referred to our hospital for fetal evaluation following the identification of a brain cyst at 36 weeks of gestation in an obstetric clinic. Before the referral, the course of her pregnancy had been uneventful. The estimated fetal body weight was 2832 g. We observed the cystic structure, with its longest diameter of 25 mm, in the left thalamus area. Swirling blood flow was observed within the brain cyst by color Doppler ultrasound examination in the fetus (Figure 1A and B), while there was no ventriculomegaly or intracranial hemorrhage. These characteristics of the cystic structure were also observed by prenatal MRI. From the above findings, we diagnosed this case as VGAM. The aneurysmal volume calculated on the basis of three-dimensional ultrasound and MRI was calculated as 9.51 cm³ (Figure 1C) and 9.63 cm³ (Figure 2D), respectively. In addition, as prenatal signs of cardiovascular disorders, cardiomegaly, a dilated superior vena cava, and tricuspid regurgitation were detected.

Figure 1:

Ultrasound assessment of VGAM in the fetal brain.

(A) Demonstration of blood flow in the cystic structure in the posterior middle-left portion of the fetal brain. Dilated and tortuous abnormal vessels (arrows) from the territory of the left posterior cerebral artery inflow cystic structure (arrowheads). (B) A three-dimensional rendered image of color-Dopper blood flows. The dilated and tortuous artery (arrows) and cystic structure (arrowheads) were clearly visualized. The left middle cerebral artery could not be detected due to the influence of the overflowing color image of the dilated artery. (C) A three-dimensional rendered image of VGAM. The three-dimensional image of VGAM (d) was reconstructed using horizontal (a), coronal (b), and sagittal (c) sections. The aneurysmal volume was calculated by integrating the area of each horizontal section (a).

Figure 2:

A three-dimensional rendered image of fetal VGAM by MRI.

The three-dimensional image of VGAM (D) was reconstructed using horizontal (A), coronal (B), and sagittal (C) sections. The aneurysmal volume was calculated by integrating the area of each horizontal section (A).

A cesarean section was performed at 38 weeks and 5 days, and a 2758 g male infant was delivered. Neonatal echocardiographs showed tricuspid regurgitation, a dilated superior vena cava, and diastolic regurgitant flow of the arch of the aorta. In the early postnatal period, the infant was observed with the medical management of heart failure. However, at 1-day-old, the exacerbation of heart failure led to a state of oliguria and peripheral circulatory insufficiency. Emergency intravascular treatment following MRI was performed. There was no obvious brain damage, and the calculated aneurysmal volume was 9.68 cm³ based on MRI (Figure 3C).

Figure 3:

The MR images of the neonatal brain.

(A) A transverse section at 1 day old before embolization: The aneurysm (arrowheads) and dilated drainage vessel (arrow) were observed in the left thalamus area. (B) A transverse section one month after embolization. The size of the aneurysm (arrowheads) and dilated drainage vessel (arrow) were markedly reduced. No abnormal finding was observed in other areas. (C) A three-dimensional rendered image of VGAM based on MRI at one day old before embolization (A). The aneurysmal volume was calculated by integrating the area of each horizontal section.

We observed a markedly dilated and tortuous artery and several feeders creating a shunt to the aneurysm on cerebral angiography. We adopted two thicker vessels and performed embolization with no complications. After embolization, diminished shunt flow to the brain was observed. After a month of embolization, we observed reduction in the size of the aneurysm, feeding vessels, and drainage vessels by brain MRI (Figure 3A and B). The infant was making satisfactory progress and discharged at 33 days old. The 2^nd and 3^rd procedures were performed at 9 and 18 months of age. A total of three procedures led to disappearance of the shunt flow, and no neurological developmental problems have been observed for 5 years.

Discussion

This is the first case report evaluating morphological changes in VGAM when the exacerbation of heart failure occurred after birth. Not only ensuring survival but also achieving a favorable neurodevelopmental prognosis is a goal of treatment for patients with VGAM [1]. Yuval [2] proposed prenatal ultrasound indices that may predict the short-term perinatal prognosis. In their report, anatomic brain changes and hydrops were associated with an adverse perinatal outcome. However, the prenatal findings to predict the long-term neurodevelopmental outcome of VGAM patients have not been well described.

Fullerton [3] reported that developmental delay occurred in about 16–40% of their patients. They also showed that choroidal type lesion and presentation with congenital heart failure were associated with a poor outcome. Li [4] showed that the age at the time of embolization is the only associated with a poor prognosis.

In general, neonatal cerebral circulatory disturbance that causes hypoxic-ischemic encephalopathy can lead to subsequent developmental delay. Accordingly, we hypothesize that post-delivery cerebral circulatory disturbance is one of the main causes of developmental delay of VGAM patients.

Following birth, low resistance remains within the cerebral arteriovenous shunts in VGAM, resulting in a further increase in the blood flow of the aneurysm [5]. This may promote the relative imbalance between the blood flow of the aneurysm and the other cerebral parts. Enlargement of an aneurysm may also compress certain cerebral parts.

Cerebral aneurysmal left-to-right shunt increases the right-side cardiac preload and decreases the diastolic coronary blood flow, which cause the exacerbation of cardiac failure [5]. Cardiovascular decompensation exacerbates the increase in aneurysmal pressures, resulting in morphological changes of the aneurysm. Since the severe and continuous cerebral circulatory disturbance may concurrently proceed in parallel with the above sequential cascade, we hypothesize that the morphological changes of aneurysms can be a possible parameter of the long-term prognosis.

However, there have been few studies calculating the aneurysmal volume by three-dimensional ultrasound [6–8] (Table 1), and no study has evaluated the volume changes of aneurysms when the exacerbation of heart failure occurred after birth.

In this case, we successfully evaluated the volume of an aneurysm in pre- and postnatal periods using ultrasound and MRI. The postnatal aneurysmal volume was almost the same as the prenatal volume. Importantly, no developmental delay was observed during the 5-year follow-up. This outcome supports our hypothesis that the stability of the VGAM volume even under the exacerbation of heart failure is one of the useful parameters to predict a favorable long-term prognosis, proposing that the neurological prognosis may primarily depend on the morphological changes of aneurysms with or without heart failure. Although we could not provide more precise data concerning blood flow in VGAM, it should also be noted that a cerebral blood flow steal by shunting in VGAM may be another possible factor causing neurodevelopmental delay.

In conclusion, the post-delivery morphological changes in VGAM can be possible parameters to predict the long-term neurodevelopmental prognosis. To assess the changes precisely, pre- and postnatal morphological analysis by three-dimensional ultrasound and MRI may be recommended in VGAM cases. Further clinical data should be accumulated to evaluate the relationship between post-delivery morphological changes in VGAM and the long-term developmental prognosis.