Vein of Galen aneurysmal malformation diagnosed prenatally: A case report

Abstract

The vein of Galen aneurysmal malformation is a rare congenital malformation of the cerebral blood vessels. It is a result of the persistence of an embryonic vessel that drains multiple arteriovenous shunts. This malformation can cause a multitude of symptoms ranging from cardiac failure to headaches depending on the age of presentation. In the fetus, cardiac manifestations are rare and are linked to a very poor prognosis. That’s why prenatal diagnosis is crucial in early detection and management. We present a case of a vein of Galen aneurysmal malformation, diagnosed prenatally with ultrasonography. The newborn developed widely a high-output cardiac failure. Prenatal diagnosis facilitates the early detection of this malformation as well as predicting the prognosis.

Background

The vein of Galen aneurysmal malformation (VGAM) is a rare congenital malformation of the cerebral blood vessels. It occurs during the embryonic stage as a result of the persistence of the median prosencephalic vein of Markowski and the development of arteriovenous shunts. ¹ The symptoms vary with age ranging from congestive heart failure in neonates to neurocognitive delay in infants and adults. ² Prenatal detection of this malformation is crucial in early detection and proper treatment planning through a multidisciplinary approach. ³ We describe a case of VGAM whose diagnosis was suggested at antepartum ultrasonography and that was confirmed after birth. This case was remarkable because the intrauterine ultrasound signs of heart failure, suggested a poor prognosis, indicating an intractable high-flow anomaly.

Case report

A full-term boy, weighing 3,250 gr was born at 38 weeks gestation. The pregnancy was complicated by pre-eclampsia. An antenatal ultrasound at 36 weeks of gestation demonstrated a cerebral aneurysm and cardiomegaly. A fetal Magnetic resonance imaging (MRI) was missed when the baby had to be delivered via emergency c-section due to fetal distress. At birth, the APGAR scores were 8 and 9 at 1 min and 5 min of life, respectively. The head circumference was 34 cm (25th–50th percentile). Physical examination revealed an accentuated second heart sound, a systolic murmur, and a continuous cranial murmur. The newborn was eupneic and hemodynamically stable. A chest radiography showed a cardiomegaly. An echocardiogram revealed the presence of a dilated right atrium but was otherwise normal. A transfontanelle ultrasound showed a 30 × 24 mm oval lesion situated behind the tectal plate and slightly lateralized to the left. On Doppler, the malformation was heavily vascularized and connected to multiple arterial and venous blood vessels. MRI and angiography confirmed the diagnosis of a VGAM with multiple arterial feeders and venous drainage that goes through a dilated straight sinus. There were no signs of hydrocephaly, cerebral hemorrhage, or parenchymal lesions (Figure 1).

Figure 1.

Cerebral magnetic resonance imaging showed an aneurysm of the Galen vein and vessels feeding the aneurysm.

On the fifth day of life, the newborn developed signs of cardiac failure with mottled skin, prolonged capillary refill time, cyanosis with oxygen saturation at 85%, hepatomegaly, peripheral edema, and gallop sound. Blood analysis showed an increased C-reactive protein level, thrombopenia, and functional renal insufficiency. Furosemide and large-spectrum antibiotics were commenced after performing a blood culture which came back positive for Klebsiella pneumonia. An echocardiogram confirmed biventricular dilation, left ventricular dysfunction, and supra-systemic pulmonary hypertension. The diagnosis was an acute cardiac failure secondary to a VGAM associated with a healthcare-associated infection. Due to the poor prognosis and the severity of the case, endovascular embolization was not performed. He died at 13 days of age.

Discussion

The VGAM is a rare congenital vascular malformation that accounts for 1% of all arteriovenous malformations and 30% of pediatric vascular anomalies. ¹ During the embryonic stage, cerebral vascularization is ensured by choroidal arteries. The median prosencephalic vein of Markowski assumes venous drainage. ² This structure is the precursor to the vein of Galen. Around the 11th week of gestation, cortical arteries develop and take over the cerebral vascularization. The median prosencephalic vein of Markowski involutes leaving only the posterior segment which drains the internal cerebral veins, thus forming the vein of Galen. ¹ In the VGAM, the anterior segment of the median prosencephalic vein of Markowski persists due to shunts with choroidal arterial feeders. This causes its enlargement and the formation of an aneurysmal sac. ² The drainage of the VGAM can be done through a normal straight sinus or an embryonic falcine sinus.^1,2

Clinical presentation varies with age. The manifestations are mostly cardiac and neurologic. ¹ In the infantile age group, this malformation usually leads to hydrocephalus and seizures. Cranial bruit, proptosis, and dilated scalp veins are also observed in infants. ² However, Neonates usually present with high-output cardiac failure. Symptoms appear after birth due to the transition from fetal to neonatal circulation. In the fetus, cardiac manifestations are rare and are linked to a very poor prognosis. The high-flow fistula that is present in a VGAM causes an increase in blood volume in all of the heart chambers and thus cardiac output. The closure of ductus arteriosus aggravates the situation leading to right then left heart failure. Coronary blood flow is decreased resulting in myocardial ischemia. Diastolic flow reversal occurring in the descending aorta results in low perfusion and multiorgan failure. ⁴ Although this disease is rare, it should be included in the differential diagnosis of any case of heart failure of unknown etiology in newborns or infants, for which auscultation of the fontanel and chest are key elements of the physical examination. In the reported case, the neonate rapidly developed severe congestive heart failure after 5 days following sepsis.

The diagnosis can be made prenatally starting from the second trimester of gestation. Ultrasound shows a hypoechogenic cystic structure located posterior to the third ventricle with arterial and venous flow turbulences. ³ However, some limitations make ultrasound less effective in detecting malformations such as maternal obesity and bowel gas, oligohydramnios, and limited penetration through the fetal ossified skull. ⁵ In the reported case, a prenatal diagnosis was made via ultrasound but an MRI was unfortunately missed. Fetal MRI holds a key role in prenatal diagnosis of VGAM. It offers better precision in determining its location and its impact on the neighboring brain tissue. ³ It can detect the signs that are predictive of poor prognosis such as brain atrophy and heart failure. Fetal MRI can also identify middle cerebral artery pseudo-feeders which are correlated with encephalomalacia, pulmonary hypertension, and heart failure. ⁴

It is important to note that the size of the malformation is not indicative of poor prognosis. ⁵ However, there have been specific radiologic metrics that can predict the clinical course. ⁶ This has been used to guide inclusion into a clinical trial. ⁷

However, intrauterine ultrasound signs of heart failure, such as cardiomegaly, tricuspid insufficiency, polyhydramnios, pericardial and pleural effusion, edema, and ascites carry a poor prognosis and indicate an intractable high-flow anomaly. ³ The association with heart failure or severe brain damage can justify palliative treatment after birth. ¹

The choice of a treatment plan is based on the patient’s age, clinical manifestations, and imaging findings. The first step of treatment is to stabilize the patient, especially in neonates who present with high-output cardiac failure. No consentaneous strategy has been established. Diuretics, vasodilators, and inotropic agents have shown great efficiency in reducing the flow to the VGAM thus decreasing pulmonary hypertension and improving kidney and liver perfusion. ⁸ Endovascular therapy by embolization has become the premium treatment option for the VGAM. The malformation can be targeted via a transvenous or a transarterial route. The latter provides better hemodynamic control and a lesser risk of complications. ⁹ The femoral or umbilical artery can be used for access. Transvenous embolization is reserved for cases where transarterial access is not possible or for the final stages of embolization. Venous access is gained via the femoral or jugular veins or the torcula.^2,9 Urgent endovascular intervention is performed in cases of cardiac heart failure, developmental delay or regression, and ischemic signs on imagery. Otherwise, the treatment should be delayed to 5 or 6 months of age for better results.^9,10 Surgical treatment is only reserved for cases in which endovascular treatment has failed or for evacuating intracranial hematomas. ² The neonate in the reported case presented with severe cardiac failure which is associated with a very poor prognosis. This didn’t make him a candidate for endovascular or surgical treatment.

The outcome of this malformation is related to many factors such as clinical manifestation, the presence of multiorgan failure, neurological delay, and parenchymal calcifications. ⁷

Conclusion

The diagnosis of the VGAM must be considered in every infant presenting with heart failure with no underlying cardiac cause. Prenatal diagnosis plays a key role in early detection and treatment of this malformation as well as predicting the prognosis. The management of VGAMs is multidisciplinary and requires the involvement of the intensivist, the radiologist, and the neurosurgeon. To ensure better management of VGAM in our country, it is necessary to develop endovascular embolization techniques and establish specialized centers.