Vein Of Galen Malformation Classification Essay



 
 
ORIGINAL ARTICLE
Year : 2017  |  Volume : 11  |  Issue : 3  |  Page : 630-635 

Periprocedural management of vein of galen aneurysmal malformation patients: An 11-year experience

Ajay Prasad Hrishi, Karen Ruby Lionel
Department of Anaesthesiology, Neuroanesthesia Division, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India

Date of Web Publication07-Apr-2017

Correspondence Address:
Ajay Prasad Hrishi
Department of Anaesthesiology, Neuroanesthesia Division, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala
India

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aer.AER_252_16

   Abstract 

Context: The vein of Galen aneurysmal malformation (VGAM) is a rare arteriovenous malformation where a dilated median prosencephalic vein provides a low-resistance conduit for intracerebral blood flow resulting in high-output cardiac failure, severe pulmonary hypertension, with or without central nervous system symptoms secondary to hydrocephalus, in the neonatal and pediatric population. Aim: This study aims to analysis of the anesthetic management of this unique subset of patients with VGAM. Settings and Design: This was a retrospective analysis of case series of VGAM patients admitted between January 2005 and June 2016 in our Institute. Subjects and Methods: Case records of VGAM patients were reviewed for the anesthetic technique and medications administered. The incidence of intra-and post-procedural complications and their management and outcomes were analyzed. Statistical Analysis: Parametric data were expressed as mean and standard deviation. Descriptive statistics was used for describing associated pathologies, drugs and monitors used during the procedure, incidence of any adverse events, and the treatment protocol. Results: Twenty-one patients underwent treatment for the VGAM. There were a total of forty anesthetics administered for embolization, diagnostic angiography, and magnetic resonance imaging. Eighty-five percent had increased head circumference, 40% had associated focal neurological deficits, and 15% had seizures as presenting symptoms. Cardiac anomalies were seen in 41% of the patients, and difficult airway was anticipated in 38% of the patients. The majority of the patients had inhalational induction (62.2%) and inhalation maintenance (84.4%) of anesthesia. Intraprocedural adverse events were noted in 43% and postprocedure complications in 38% of the patients. Conclusion: Anesthetic management for embolization of VGAM with a combination of opioids and inhalational agents helps in minimizing the incidence of intraprocedural adverse events and provides a better hemodynamic profile.

Keywords: Anesthetic implications, interventional neuroradiology, vein of Galen aneurysmal malformation


How to cite this article:
Hrishi AP, Lionel KR. Periprocedural management of vein of galen aneurysmal malformation patients: An 11-year experience. Anesth Essays Res 2017;11:630-5

How to cite this URL:
Hrishi AP, Lionel KR. Periprocedural management of vein of galen aneurysmal malformation patients: An 11-year experience. Anesth Essays Res [serial online] 2017 [cited 2018 Mar 11];11:630-5. Available from: http://www.aeronline.org/text.asp?2017/11/3/630/204092


   Introduction 


The Vein of Galen Aneurysmal Malformation (VGAM) is a rare (1/25,000 deliveries) arteriovenous malformation that presents in the pediatric and neonatal age group.[1],[2] Here, the dilated median prosencephalic vein provides a low-resistance conduit for intracerebral blood flow, ensuing in high-output cardiac failure, and severe pulmonary hypertension with or without central nervous system symptoms secondary to hydrocephalus [Figure 1]. Chronic progressive hydrocephalus attributed to absorptive malfunction secondary to high intracerebral venous pressure results in macrocephaly with cerebral atrophy [Figure 2] and the child not attaining developmental milestones appropriate for age.[3],[4],[5] The VGAM serves as a large intracerebral shunt causing hypoperfusion of the normal brain tissue thus exacerbating neurological injury. This complex pathophysiology also fosters a systemic hypoperfusion which may present as renal and hepatic dysfunction.
Figure 1: Vein of Galen aneurysmal dilatation: Carotid angiogram in a patient with vein of Galen aneurysmal dilatation showing an arteriovenous malformation draining into a dilated venous sac

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Figure 2: Computed tomography scan in a 9-month-old child with vein of Galen malformation. Plain axial computed tomography scan of the brain showing dilated ventricles due to hydrocephalus and gross cerebral atrophy

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Neuroradiological intervention with transcatheter embolism is the procedure of choice to occlude the VGAM owing to the fact that it is less invasive and has a higher survival rate than open neurosurgical procedures.[6],[7],[8] Anesthetic and critical care management of these patients prove to be a challenge due to the risk of periprocedural complications such as congestive cardiac failure (CCF) and cerebral infarction. Furthermore, the airway management of these neonates and infants with macrocephaly secondary to the VGAM and hydrocephalus presents a unique challenge.

A PubMed search regarding VGAM and its management yielded isolated case reports. This is again attributed to the rarity of this complex pathology and presentation of patients with VGAM. An analysis was done to identify the optimal anesthetic and intensive care management of this group of patients as till date there are no set protocols or guidelines referring to the management of the same. This is again attributed due to the rare incidence of VGAM making clinical analysis of the optimal anesthetic and intensive care management a difficult task. We hereby report an 11-year retrospective analysis of the periprocedural management of VGAM patients, which, to the best of our knowledge is the largest case series from a tertiary care neurological center.


   Subjects and Methods 


Since prospective studies are not feasible in the setting of rare pathologies such as VGAM, we decided to retrospectively analyze a case series over the past one decade. We present the data as a descriptive essay of a large case series identifying the optimal clinical management based on our reliable databank. We also illustrate the difficulties commonly encountered in managing these cases and their management at our tertiary care center. After approval from the Institutional Ethics Committee, a retrospective analysis of case records of VGAM patients from January 2005 to June 2016 was performed. Data were collected using a data collection pro forma, and the records were screened for information regarding eight nonvariable entities: (i) Patient demographics, (ii) presence or absence of associated cardiopulmonary involvement, (iii) presence of comorbid illnesses, (iv) airway assessment, (v) baseline hemodynamic parameters, (vi) intraprocedure adverse events, (vii) management of intraprocedure adverse events, and (viii) postprocedural complications. Any case records which did not convey data regarding all these eight clinical entities were deemed incomplete and were not included in the analysis. We followed this method to avoid clinical bias and other confounding variables. The primary parameter assessed was the periprocedural management, including the anesthetic technique used during the neuroradiological intervention for the VGAM. The incidence of intra- and post-procedure complications, their management, and the outcome were the secondary parameters investigated.

We defined an anticipated difficult airway by the following criteria: (i) Previous history of difficult bag-mask ventilation or intubation, (ii) examination revealing a large head (>2.5 standard deviation [SD] of expected), and (iii) Mallampati score of ≥3. Cardiorespiratory adverse events were defined as episodes of hypertension (>20% increase from baseline for >5 min), hypotension (>20% decrease from baseline for >5 min), tachycardia (>20% change from baseline for >5 min), and bradycardia (>20% change from baseline or heart rate <60/min for >5 min). Cardiac arrhythmias and episodes of desaturation (pulse oximetry [SpO2] >5% drop or <92%) were the other adverse events looked for.

Statistical analysis

Stata 11 software (StataCorp. 2015. Stata Statistical Software: Release 14. College Station, TX: StataCorp LP) was used for analysis. Parametric data were expressed as mean and SD. Descriptive statistics was used for describing associated pathologies, drugs, and monitors used during the procedure, incidence of any adverse events, and the treatment protocol. P < 0.05 was considered statistically significant.


   Results 


A total of 25 patients presented with the diagnosis of VGAM to the hospital during the period between January 2005 and June 2016. All of them underwent neuroradiological interventions for VGAM. Four patients were excluded from the analysis as their records it did not fulfill data collection criteria. In the 21 patients whose records were analyzed the mean age was 3.8 years and ranged between 3 months and 16 years, with a male to female ratio of 13:8.

Of these 21, 85% had increased head circumference (>2 SD for the age), 40% had associated focal neurological deficits, and 15% had seizures as the presenting feature. All patients had hydrocephalus diagnosed at the initial imaging, of which 67.6% were moderate to severe in nature. Cardiac anomalies were the most commonly associated congenital malformations as seen in 41% of the patients, out of which 75% had atrial septal defects (ASD), 12.5% ventricular septal defects (VSD), and 12.5% patent ductus arteriosus (PDA). Two (9.5%) of our patients presented with neonatal CCF and severe pulmonary arterial hypertension [Figure 3] both of whom responded to management with periprocedural sildenafil and milrinone. In our study population, 32% were found to be underweight (<2 SD of the weight for age) and 18% were anemic with one subject requiring preprocedural blood transfusion due to a low hemoglobin level of 5.7 g/dl.
Figure 3: Plain radiograph of the chest showing cardiomegaly (right ventricular hypertrophy) and features of pulmonary hypertension and hepatomegaly

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The neuroradiologic procedure carried out was transcatheter arterial embolization in all patients, and the duration of intervention ranged between 75 and 780 min with a mean duration of 340 min. A total of 34 embolization procedures were carried out in these 21 patients as 71.4% of the patients required multiple episodes of embolization during the study period owing to the fact that total embolization of a large shunt in a single sitting can result in rapid deterioration of both cardiac and neurological status due to the sudden removal of a high flow shunt from the circulation. The embolization material used was N-butyl cyanoacrylate (n = 20), or ethylene vinyl alcohol copolymer (n = 14). There were a total of forty anesthetic procedures carried out, of which 85% of the anesthetics were for embolization, 5% were for follow-up check angiography, and 10% were for diagnostic magnetic resonance imaging (MRI).

Preprocedural assessment of the airway revealed that 38% had an anticipated difficult airway, of whom 40% had a Cormack and Lehane (CL) Grading of 1 or 2 and 60% had a CL Grade 3. Out of the total anticipated difficult airways in the study population, 60% were intubated at the first attempt and 40% required 2 or more attempts at intubation aided by airway gadgets (bougie/video laryngoscope).

Among the anesthetics administered to these patients with VGAM, 62.2% had an inhalational induction with sevoflurane. In patients who had an intravenous (IV) induction, 82.3% received injection propofol (1–2 mg/kg), and the rest received injection thiopentone (4–7 mg/kg). Both groups were given injection fentanyl 1–2 μg/kg and injection vecuronium 0.1 mg/kg to facilitate endotracheal cannulation. Mechanical ventilation was done with pressure control mode targeting a tidal volume of 8–10 ml/kg. Anesthesia was maintained in 84.4% of the anesthetics with a combination of sevoflurane up to 0.8 minimum alveolar concentration (MAC), oxygen and air mixture (50:50) and an infusion of injection fentanyl (1–2 μg/kg/h), while the rest received total IV anesthesia (TIVA) with injection propofol (75–100 μg/kg/min) and injection fentanyl (1–2 μg/kg/h). The anesthetic management for diagnostic angiography and MRI was done under sedation with injection propofol (25–75 μg/kg/min) with supplemental oxygen up to 60% FiO2, through face mask. In addition to the routine preinduction monitors of electrocardiograph, SpO2 and noninvasive blood pressure, all patients who underwent embolization had invasive arterial blood pressure (ABP), central venous pressure (CVP), and temperature monitoring as well.

The analysis of intraprocedural adverse events revealed an overall incidence of 43% with episodes of hypotension in 33.3%, hypertension in 13.3%, tachycardia in 11%, and bradycardia in 6.6% of the patients. Postinduction hypotension was higher with IV induction (20%) as compared to the inhalational method (13%), but this was not statistically significant (P > 0.05). About 90% of the hypotensive episodes were managed successfully with IV fluid boluses and injection mephentermine 3 mg boluses. Two infants with preprocedural CCF on treatment with tablet digoxin and injection furosemide responded well to an injection milrinone infusion (0.35–0.75 μg/kg/min). Intraprocedural tachycardia and hypertensive episodes occurred more frequently in patients maintained on inhalational anesthetics (68.9%) when compared to the TIVA group, and this was statistically significant (P < 0.05). Tachycardia was managed successfully in 66.6% of the patients with fentanyl boluses (1–2 μg/kg) and the rest responded to an additional increase in the depth of anesthesia up to 1.0 MAC. In patients who developed hypertensive episodes, 50% settled after fentanyl boluses (1–2 μg/kg) while the other half required injection sodium nitroprusside (SNP) infusion (2–5 mcg/kg/min). Bradycardia was noticed during the deposition of the embolizing material in two patients receiving TIVA compared to one patient in the inhalational group. One of the patients with bradycardia in the TIVA group required treatment with atropine while the others were transient and recovered spontaneously. Other adverse intraprocedural adverse events such as desaturation, arrhythmias, or cardiac arrest did not occur. No adverse events were noted during diagnostic angiography or during MRI procedures.

Postprocedure, all patients were shifted to the interventional radiology Intensive Care Unit for monitoring for a minimum period of 48 h. Postprocedural complications were seen in 38% of patients who underwent embolization. Three patients had transient low sensorium; one had persistent seizures in whom the postprocedural imaging revealed bilateral thalamic infarcts and two other patients had worsening of hydrocephalus requiring placement of external ventricular drains. Another patient presented with an acute drop in Glasgow Coma Scale, 6 h postprocedure due to accelerated thrombosis of the embolized VGAM requiring emergent intubation. One patient who was intubated for worsening of CCF later required a tracheostomy since the cardiac failure was worsened by severe respiratory distress secondary to sepsis. This patient also had a cardiac arrest in the immediate postprocedural period requiring cardiopulmonary resuscitation which was successful. None of the patients presenting for diagnostic procedures had complications.

Sedation for postprocedural mechanical ventilation was instituted with morphine (0.1 mg/kg/h) and midazolam (0.05–0.1 mg/kg/h) infusion in 87.5% of patients, while the rest received injection dexmedetomidine (0.2–0.5 mcg/kg/h) infusion. Pressure control ventilation was used in all patients who required postprocedural ventilation.


   Discussion 


Although this unique condition falls under the broad classification of intracerebral arteriovenous malformations, the anesthetic implications of VGAM vary drastically due to the associated multiple systemic complications and early presentation in life. Our review revealed that majority of our patients presented at a higher average age with neurological symptomatology, such as increased head circumference, neurological deficits, and seizures, in contrast to their counterparts in developed countries where children usually presented in the neonatal period with cardiac symptoms.[9],[10] Hence, our management was tailored to address the same, with goals to ensure no further deterioration in the neurological status by avoiding any further raise in intracranial pressure (ICP), maintenance of normal cerebral perfusion pressure (CPP), and cerebral oxygenation. Our anesthetics were titrated keeping in mind the cerebral steal circulation along with the coexistence of cardiopulmonary pathologies.

The most commonly associated congenital anomalies in our population were structural heart pathologies consisting of ASD, VSD, and PDA with two patients having an Eisenmenger's complex. Both these patients responded well to periprocedural sildenafil and milrinone as our goals were to increase the cardiac output and to keep the systemic vascular resistance (SVR) and peripheral vascular resistance (PVR) low. These patients further sustain a cardiac insult attributed to the fact that blood flow through the VGAM during diastole, creates a steal phenomenon causing a reduction in diastolic pressure which may lead to myocardial ischemia secondary to reduced coronary blood flow.[9],[10]

The majority of these patients fail to thrive due to poor feed tolerance and easy fatigability as seen in children with cardiac failure. The associated nausea and vomiting attributed to the hydrocephalus compounds this, causing them to be malnourished and anemic. Anemia further worsens the existing hyperdynamic circulation and also reduces oxygen delivery to the brain. Thus, a higher PaO2 (100–250 mmHg) is required to ensure adequate brain and peripheral tissue oxygenation, and a higher transfusion trigger (10 g/dl) is preferred as well.[11],[12] Malnourishment leads to hypoproteinemia aggravating the circulatory failure, tissue edema, and altered pharmacokinetics.[13],[14]

All patients undergoing embolization had invasive monitors which included ABP and CVP. Invasive hemodynamic monitoring in these cases proves to be pivotal due to associated coronary heart disease (CHD) and also in optimizing the CPP. The large shunt through the VGAM, compromises blood flow to the peripheries, resulting in collapsed veins and barely felt arterial pulses which makes venous and arterial cannulation a difficult task. Central venous cannulation particularly of the internal jugular vein is a challenge as the intracranial shunt makes even the venous column pulsatile. Furthermore, venous blood appears bright to the naked eye due to low central oxygen extraction which is reflected as a high partial pressure of oxygen in the blood gas sampled from the venous line. Thus, central venous cannulation must be carried out under ultrasound guidance. Longer cables for all monitors as well as adequate length of breathing circuits must be ensured.

More than a quarter (38%) of our patients had an anticipated difficult airway, of which 40% required 2 or more attempts to intubate the trachea. This difficult airway scenario is mainly due to the presence of a larger head compared to normal subjects of the same age and the challenging airway anatomy of the neonate and infant. This can be overcome by stabilizing the head in a head ring and using a small pillow/roll under the back or shoulders to achieve a proper sniffing position, further aided by airway gadgets such as a gum elastic bougie or video laryngoscope. A quick airway establishment is important in this population as they tend to desaturate faster due to the associated congenital heart disease.[15],[16]

In our center, the preferred anesthetic technique for induction was inhalational, using sevoflurane and majority of our patients were maintained with a combination of sevoflurane and fentanyl infusion and the remaining were maintained with propofol and fentanyl TIVA. Postinduction hypotension was higher in patients who underwent IV induction, and though this was not statistically significant (P - 0.12), it was probably attributed to the cardiac depressive effect of thiopentone and propofol.[17],[18] The conventional ketamine induction which is advocated in patients with CHD cannot be utilized here due the risk of aggravating the ICP/seizures and thereby worsening the neurological status.[19] Thus, a titrated inhalational and opioid induction would be beneficial in this subset of patients. Maintenance with isoflurane or sevoflurane is optimal as it has minimal effect on the myocardial contractility or shunt fraction.[20] The increased incidence of tachycardia and hypertensive episodes in the inhalational group maybe due to the inadequate depth of anesthesia possibly due to the slow uptake of the inhalational agent attributed to the cardiac shunt and also to a low target site concentration due the intracranial shunt. These episodes were managed effectively by supplemental doses of opioids and by deepening the anesthetic plane. The hypertensive episodes refractory to this can be effectively management by short-acting vasodilators like SNP which being a nitric oxide donor, improves the pulmonary circulation as well as the cardiac output by reducing the SVR.[21],[22] Hypotensive episodes in these patients can be effectively managed with boluses of short-acting vasopressors like injection mephentermine or injection phenylephrine. Hypotension is commonly encountered due to intraarterial use of vasoactive agents like nimodipine, SNP, and milrinone by the neuroradiologists. Dislodgement of glue (N-butyl cyanoacrylate) during the neurointervention can present with pulmonary embolism-like features. Bradycardia is encountered during embolization of large intracranial shunts. This is attributed to the sudden transient raise in ICP caused by the occlusion of the low-resistance intracranial shunt.

Intraprocedure positioning of the macrocephaly child must be done with great care to prevent kinking of the neck vessels. We position our neonates and infants using a doughnut head pillow to accommodate the large head and a flat pillow below the trunk to avoid hyperflexion. Fluid management too proves to be a difficult task since urine output monitoring will not reflect the volume status, as these patients are on periprocedural diuretics and osmotic agents for the management of the raised ICP, thus warranting intraprocedural CVP monitoring and appropriate replacement with dextrose-free crystalloids.[23] Contrast-induced diuresis caused by hyperosmolar contrast agents and cold diuresis in the interventional radiology suite further aggravates the preexisting hypovolemia and dyselectrolytemia. Hypothermia, commonly encountered in the interventional suite increases the SVR and also delays drug metabolism. Hence, careful temperature monitoring and use of forced air warmers are mandatory.

Postprocedural complications were seen in 38% of patients which included development of new focal neurological deficits, seizures, worsening of hydrocephalus, and precipitation of CCF thus requiring the expertise of the anesthesiologist in securing the airway, mechanical ventilation, and hemodynamic resuscitation. During the postembolization phase, there is a drastic shift in the intracranial circulatory dynamics as occlusion of the low-resistance high-volume conduit results in cerebral hyperperfusion, cerebral edema, and venous infarcts. Other complications include intracranial hemorrhage, cerebral venous thrombosis, and worsening of the hydrocephalus. Hypertension needs to be avoided in the first 48 h after the procedure to prevent neurological hyperperfusion injury, and this is effectively achieved with an infusion of SNP.[9],[10] Exclusion of the low-resistance circuit from the circulation will increase the afterload, transiently worsening the cardiac status of these patients, who usually respond well to milrinone. Sedation in the postoperative period is best achieved with morphine which aids in improving the PVR, apart from providing excellent analgesia and sedation for mechanical ventilation. Pressure control mode of ventilation is preferred, due to the poor lung compliance secondary to pulmonary edema, which can be a common presentation during the postprocedural period.

The anesthetic management of diagnostic procedures inclusive of both angiography and MRI under IV sedation with propofol (25–75 mcg/kg/min) did not have any intra- and post-procedural adverse events. This is ascribed to the fact that there were no alterations in the circulatory dynamics.

This study, apart from representing a small population, due to the rarity of this condition also has the limitation that it does not represent patients who have undergone surgical management of the same. Anesthesia for surgical management will present an even more challenging situation to the anesthesiologist due to perioperative surgical stress, blood loss, dynamic homeostasis, and increased incidence of postoperative complications.[6],[7] A prospective study will be time-consuming and may not be clinically feasible because of the low incidence of cases of VGAM, thus making this large case series a valuable source of clinical information.


   Conclusion 


VGAMs are a rare presentation, with a plethora of pathologies which include neurological deficits, associated congenital heart disease with or without cardiac failure and difficult airways. The goals of management are to avoid further neurological injury by maintaining normal CPP, cardiac stability, and providing a quiet field for successful VGAM embolization. Anesthetic management for embolization of VGAM with a combination of opioids and inhalational agents helps in minimizing the incidence of intraprocedural adverse events and also provides a better hemodynamic profile.

Acknowledgment

Dr. Jayadevan E.R., Associate professor, Imaging sciences and Intervention radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India, for his expert opinion and guidance.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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Etsten B, Li TH. Hemodynamic changes during thiopental anesthesia in humans: Cardiac output, stroke volume, total peripheral resistance, and intrathoracic blood volume. J Clin Invest 1955;34:500-10.  
    
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Mohindra R, Beebe DS, Belani KG. Anaesthetic management of patients with congenital heart disease presenting for non-cardiac surgery. Ann Card Anaesth 2002;5:15-24.  
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    Figures

  [Figure 1], [Figure 2], [Figure 3]

Abstract

The Vein of Galen aneurysmal malformation (VGAM) is a rare and complex arteriovenous (AV) malformation found in about 1% of all fetal AV abnormalities. The high morbidity and mortality requires an early and precise diagnosis to counsel parents and guide physicians for pre-, peri- and postnatal management as well as for prediction of outcome. Fetal MRI is a safe, important and well-established diagnostic tool in the clinical evaluation of fetuses with suspected cerebral anomalies and has become superior to color Doppler ultrasonography in the diagnosis of VGAM in recent years. It provides highly sensitive information not only about the VGAM and related brain injury but also about the systemic impact of the malformation on the fetus. In this report we present the fetal MR imaging findings including the progressing brain injury known as “melting brain”.

Introduction

Arterio-venous anomalies involving the vein of Galen are rare and complex vascular lesions with an incidence of about one in 25000 with a male predominance of 3:1. According to Lasjaunias [1] these vascular lesions can be classified by its angioarchitectural characteristics as a VGAM, and a vein of Galen aneurysmal dilatation (VGAD). A VGAM is an arterio-venous (AV) malformation in which arteries directly connect to a persistent dilated embryonic prosencephalic vein of Markowski whereas in a VGAD arteries directly drain into a dilated but already formed vein of Galen. The vein of Galen is a short trunk which is being formed by the union of the two internal cerebral veins and the basal veins of Rosenthal. If left untreated a VGAM or VGAD has an almost 100% morbidity and mortality. The first attempts of treating these malformations were recorded in an infant with intracranial hypertension in the early 20th century [1,2-8]. It can be diagnosed as early as week 6 to 11 of gestation, but is usually not detected prior to the 24th week of gestation [9]. Two- (2D) and three- (3D) dimensional ultrasound (US), Doppler color US and magnetic resonance imaging (MRI) are the main diagnostic techniques during pregnancy.

Due to the significant arterio-venous shunting and “arterialization” of the draining vein of Galen or persistent vein of Markowski, the normal drainage of the intracerebral veins is impaired increasing the risk for chronic intraperenchymal venous stasis and/or ischemia. This chronic venous congestion may result in a progressive destruction of the hemispheric white matter and overlying cortex known as the “melting brain syndrome”. Furthermore the increased venous pressure impairs the resorption of cerebrospinal fluid at the Pachionic granulations with subsequent hydrocephalus which may be aggrevated by direct compression and obstruction of the Sylvian aqueduct by the dilated vein of Galen [3,6]. Furthermore systemic complications of the AV-shunting include congestive heart failure, pleural and pericardial effusions, ascites as well as generalized subcutaneous edema (fetal hydrops).

As described in the literature [7,10] VGAM/VGAD have a very poor outcome, in particular if a “melting brain” develops or significant systemic complications ensue. Termination of the pregnancy is often considered when the fetus presents with multi-organ failure or brain parenchymal change. However, there are certain factors like Neonatal score > 12 (described by Lasjaunias) or no parenchymal changes (p<0.003), no calcifications (p<0.046), or no arterial steal phenomenon (p<0.001) which are statistically relevant and predict a better patient outcome and possible survival [10]. An early and complete diagnosis during fetal life is consequently essential.

We report on two different cases with fetal melting brain syndrome to emphasize the ability of fetal MRI to detect malformation and its cerebral and systemic complications.

Case report

In a 29 year old pregnant (P0121) woman, a sonogram showed intracranial lateral ventricle dilation of the fetus at 25 weeks of gestation. The corpus callosum appeared slightly wider than expected. A fetal MRI (Figure 1) was done showing moderate contour irregularity along both lateral ventricles with inhomogeneous T2 hypointense signal of the periventricular white matter along both lateral ventricles. Moderate-to-severe supratentorial hydrocephalus and volume loss of the periventricular white matter consistent with a developing “melting brain” as well as moderate cardiomegaly was detected. A significantly dilated vein of Galen (Figure 1) as well as enlargement of the straight sinus, transverse sinuses and sigmoid sinuses was seen. The posterior cereberal arteries and posterior choroidal arteries were also dilated. A follow up ultrasound examination at 31 weeks gestation showed a worsening fetal hydrops, cardiomegaly, ascites, hypoplastic aortic arch with accelerated flow, bilateral cerebral ventriculomegaly, hydrocele. A fetal echocardiogram confirmed the cardiomegaly with a dilated right-sided heart including markedly dilated superior vena cava consistent with a history of a vein of Galen Malformation. A moderate tricuspid regurgitation and moderately depressed right ventricular systolic function was also found.

Figure 1. Triplanar (sagittal, coronal and axial) T2-weighted ultrafast fetal MRI in a fetus with a VGAM. The vein of Galen is seen as an enlarged, T2-hypointense tubular structure in the midline draining into the dilated Torcula Herophilli and subsequent transverse and sigmoid sinuses. The periventricular white matter is significantly reduced in volume and mixed T2-hyper and hypo-intense, the ventricles are enlarged. Findings are characteristic for a melting brain syndrome secondary to a VGAM.

The mother was admitted for prolonged fetal monitoring, 2 doses of betamethasone, and C-section 24 hours after the last steroid dose. 36 hours after administration of her first dose of bethamethasone her Biophysical Profile became increasingly concerning (4/10) prior to 6/10 at the time of admission and the decision was made to proceed with a delivery via C-section prior to the planned 48 hours post betamethasone time. The mother tolerated the procedure well, the baby went to the NICU but did not survive its first day of life.

Case 2

In a 29 year old (P0G1) woman, routine 14-week ultrasound showed a large anterior uterine fibroid which was confirmed on a follow up ultrasound study done at 21 weeks. The fetal anatomy at that time was reported normal. The 25-week ultrasound study was concerning for an enlarged right>left fetal heart. After presenting with vaginal bleeding a maternal fetal medicine ultrasound study was performed which showed a large midline “cystic” structure with dilated intracranial vessels including a large superior sagittal sinus. There were multiple arteries near the “cystic” structure. Pulse Doppler showed high velocity flow profiles consistent with a fetal vein of Galen aneurysmal malformation. Right sided cardiomegaly was seen with moderate-to-severe systolic tricuspid regurgitation. Enlarged vena cava and dilated neck veins were also reported.

In order to further evaluate the anomaly a fetal MRI (Figure 2a) was performed which confirmed a large T2 hypointense tubular structure in the region of the expected location of the vein of Galen, significant elongation and partially deviation to the right of the midline of the vein of Galen which was draining into a significantly dilated torcula Herophilli as well as significant dilatation/widening of the transverse sinus bilaterally, sigmoid sinus and jugular veins. Multiple dilated feeding arteries were noted originating from the circle of Willis predominantly of the carotid arteries bilaterally, draining into the dilated vein of Galen to the right of the midline. The ventricles were of normal size for gestational age, the hemispheric white matter and cortical gray matter unremarkable. A follow up fetal MRI 4 weeks (Figure 2b) later confirmed the vein of Galen aneurysmal malformation, however the periventricular white matter appeared significantly injured with rapidly progressing resorption of the periventricular white matter, intraparenchymal hemorrhages/calcifications, malformed overlying cortical ribbon and a vague dilatation of the ventricles consistent with a “melting brain” syndrome.

Figure 2. Triplanar (sagittal, coronal and axial) T2-weighted ultrafast fetal MRI in a fetus with a VGAM. The initial fetal MRI (a) shows the characteristic dilated vein of Galen draining into a dilated torcula Herophilli and transverse sinus. The periventricular white matter and overlying cortical ribbon are appropriate for gestational age. The follow up fetal MRI (b) four weeks later shows progressive periventricular white matter injury with developing ventriculomegaly and a malformed overlying cortical ribbon. Mild subcutaneous edema is noted along the chest wall. On both studies a large uterine fibroid is noted.

At 31 weeks the child was delivered via primary low-segment transverse cesarean section. The mother tolerated to procedure well and the baby was brought to the NICU where it passed away after 27 minutes of life.

Discussion

The Vein of Galen Aneurysmal Malformation is a rare vascular malformation with an incidence of 1% of all fetal AV abnormalities [1,8,9]. Morbidity and mortality is high, especially if a progressive brain injury develops in combination with systemic symptoms. Even though the vascular anomaly is being formed between the 6th and 11th week of gestation it usually remains un-detected until the end of the second trimester. Color coded Doppler ultrasonography typically allows to identify the vascular anomaly, however progressing white matter injury may remain underrecognized. Fetal MRI is a safe, important and well-established diagnostic tool in the clinical evaluation of fetuses with suspected cerebral anomalies and has become a valuable adjunct to color Doppler ultrasonography in the diagnosis of VGAM/VGAD in recent years [11-13]. Not only can the MRI detect cerebral anomalies in more detail but it can also give a highly sensitive information about the brain ultrastructure as well as associated systemic complications including fetal cardiac failure, pleural effusions, ascites, fetal hydrops and even placental hydrops. The “melting brain” syndrome is caused by chronic hypoxia and venous stasis due to venous hypertension which leads to rapid destruction of the white matter [1,11]. The presence of these factors are associated with poor postnatal outcome for the fetus and may result in maternal complications if not detected early. Fetal MRI provides highly sensitive imaging information relevant for prognostication and management of pregnancy and delivery. Serial or follow up fetal MRI may be necessary to identify progressive brain injury which may be too subtle or even absent on an initial, early study. Radiologists should be familiar with this devastating and characteristic “melting brain” imaging findings.

References

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  11. Wagner MW, Vaught AJ, Poretti A, Blakemore KJ, Huisman TAGM (2015) Vein of galen aneurysmal malformation: prognostic markers depicted on fetal MRI. Neuroradiol J 28: 72-75. [Crossref]
  12. Komiyama M, Nakajima H, Nishikawa M, Yamanaka K, Iwai Y, et al. (2001) Vein of galen aneurysms. Experience with eleven cases. Interv Neuroradiol 7(Suppl 1): 99-103. [Crossref]
  13. Zhou LX, Dong SZ, Zhang MF (2017) Diagnosis of Vein of Galen aneurysmal malformation using fetal MRI. J Magn Reson Imaging 46: 1535-1539. [Crossref]

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