Diagnosis and Management of a Vein of Galen Malformation in a Neonate

Transcription

1 86 JDMS 26:86-90 March/April 2010 Diagnosis and Management of a Vein of Galen Malformation in a Neonate STACY L. FRENCH, RT(R), RDMS, RVT Vein of Galen arterial malformation (VGAM) is an arteriovenous malformation between cerebral vessels of the circle of Willis and the vein of Galen. VGAM is a direct communication between an artery and a vein resulting in increased cardiac output due to arterial blood flowing directly into a vein and returning directly to the heart, without traversing the full vascular system. If left untreated, it can result in heart failure, developmental disabilities, or death. The treatment of choice is endovascular embolization. Postembolization, these patients often require medical imaging follow-up. This is a case in which neonatal neurosonography was used to image the VGAM postembolization. Key words: embolization aneurysm, vein of Galen, Vein of Galen malformation (VGAM) is a rare intracranial arteriovenous malformation that usually causes cardiac failure due to the shunting of blood. It is often detected in utero but may be discovered with neonatal neuroimaging studies. Sonography is one imaging method used to detect a VGAM, which also may be used to follow treatment of the VGAM. This case study discusses follow-up for VGAM and the important protocol additions that should be performed by the sonographer when evaluating postembolization treatment. Case Report From UWHC Ultrasound School, Madison, Wisconsin. Correspondence: Stacy L. French, RT(R), RDMS, RVT, UWHC Ultrasound School, 600 Highland Avenue, Madison, WI staceuw21@yahoo.com. DOI: / A 5-day-old male infant presented to the emergency room with increased respirations and refusal to feed. The infant was born at 40 weeks gestation without complications. The patient was transferred to another facility where an echocardiogram and

2 VEIN OF GALEN MALFORMATION IN A NEONATE / French 87 FIGURE 1. A sagittal view obtained from the anterior fontanelle demonstrating the low-resistant arterial signal in the vein of Galen malformation after the first embolization procedure. neonatal head sonogram were performed. The echocardiogram demonstrated an enlarged right atrium, enlarged right ventricle, mild narrowing of the aortic arch, and a large patent ductus arteriosus with bidirectional flow. The sonogram demonstrated a vein of Galen malformation. The patient was then transferred to a tertiary care center and magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) was performed. The MRI/MRA demonstrated a choroidal fistula; markedly dilated, tortuous intracranial vessels; and enlargement of the cerebral veins, including the vein of Galen. These findings confirmed a large choroidal-type vein of Galen malformation. Because of the intracranial shunt, cardiac failure ensued, which led to multisystem organ failure, including respiratory and liver failure. On the basis of these findings, the patient underwent a coiling embolization. Because of the size of this malformation, it was decided that this patient would need multiple procedures. Postembolization, the patient was followed with MRI and sonography. Both imaging modalities demonstrated a persistent highvelocity arteriovenous (AV) shunt and a complex arteriovenous malformation (AVM) posterior to the third ventricle (Figures 1 and 2) after the second coiling embolization procedure. The internal jugular vein remained enlarged and demonstrated arterialized flow. After the third coiling embolization procedure, the arterial signal became higher resistant, and the venous signal was noted to be less pulsatile (Figures 3 and 4). FIGURE 2. A sagittal view obtained from the anterior fontanelle demonstrating the pulsatile venous signal in the draining vein of the vein of Galen malformation after the first embolization procedure. FIGURE 3. A coronal view through the anterior fontanelle demonstrating a higher resistant arterial signal in the vein of Galen malformation after the second embolization procedure. FIGURE 4. A sagittal view through the anterior fontanelle demonstrating a decreased pulsatile venous signal in the draining vein of the vein of Galen malformation after the third embolization procedure.

3 88 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY March/April 2010 VOL. 26, NO. 2 Discussion The vein of Galen is located inferior to the corpus callosum and courses inferiorly until it becomes the straight sinus. 1 In the past, this malformation has been called a misleading and inaccurate name: a vein of Galen aneurysm. A vein of Galen malformation is, however, not a true aneurysm but is an AVM between vessels of the circle of Willis and the vein of Galen. 2 It is a rare form of an AV shunt, making up only 1% of all intracranial vascular malformations, 3 and is considered a sporadic event with a male dominance. 4 It is located midline in the choroidal fissure and consists primarily of the anterior and posterior choroidal arteries and the anterior cerebral artery. 5,6 Drainage of blood is toward one single deep vein, which becomes aneurysmally dilated. Because VGAM is a direct connection between arteries and veins, it lacks capillaries, which results in elevated velocities flowing through these vessels. Also, with this direct communication between arteries and vein, there is a direct shunt of blood flow directly back to the heart. This direct shunt back to the heart significantly increases the workload of the heart, which may result in cardiac failure. 7 The site of the anastomosis is termed the nidus. The nidus is defined as a group of anomalous blood vessels that can enlarge by incorporating adjacent blood vessels. As the malformation enlarges, it can replace normal areas of the brain. 6 Patients who have an intracranial AVM may present with cerebral hemorrhage, seizures, or decreased brain function. 8 VGAM can be associated with many different abnormalities, but the most common are hydrocephalus and congestive heart failure (CHF). CHF is the most common cause of death in infants. 2,6,9 Hydrocephalus causes an enlarged head, seizures, and delayed development. Older children are often identified because of an enlarged head circumference and failure to meet developmental milestones. Other clinical presentations of VGAM include symptoms of spontaneous VGAM thrombosis and failure to thrive. 6 Intracranial imaging findings suggestive of VGAM include areas of infarction or ischemia, which is due to the shunting. Extracranial findings include cardiomegaly, hepatomegaly, hydrops, and polyhydramnios in utero. Although most children present with FIGURE 5. An image demonstrating the coarctation of the aorta (arrow) associated with this case. symptoms earlier in life, some can have problems later on such as macrocrania or prominent veins of the face caused by obstruction of the draining veins of the malformation. 2 Congenital heart defects also may be associated with VGAM, the most common being septal defects and coarctation of the aorta. This patient had a mild coarctation (Figure 5). Transposition of the great arteries and aortic stenosis also have been reported. 6,10 Other anomalies one might also see with VGAM are supernumerary digits and hypospadias. 6 Different classifications of VGAMs have been discussed. Mitchell et al. 11 categorized VGAMs into two separate types: choroidal and mural. The choroidal type, as seen in this case, usually has bilateral blood supply from the choroidal and pericallosal arteries and usually presents in neonates who also have cardiac failure. Mitchell et al. classified the mural type as VGAMs that arise from collicular and postchoroidal arteries. Prenatal diagnosis of VGAM is essential so treatment plans can be made upon delivery. Even in utero, this abnormality early on may lead to heart failure and hydrops. If the fetus presents with no effects in utero, it may have many problems after birth caused by alterations in blood flow that impede the transition from fetal to neonatal circulation. 10 Sonography has proven to be an excellent modality in diagnosing VGAM in utero and in infancy, especially with the improvement of Doppler and new 3D/4D technology. On a prenatal sonogram, VGAM will appear as a tubular, hypoechoic structure situated midline in the fetal head superior to the thalamus and posterior to

4 VEIN OF GALEN MALFORMATION IN A NEONATE / French 89 the third ventricle. 6,10 This area has been termed the comet tail or keyhole sign. 10 If high-output cardiac failure is present as well, sonography may show an enlarged heart, hydrops, tricuspid regurgitation, and an arterialized umbilical vein. 6 The malformation often enlarges as the pregnancy progresses and is sometimes not detected until the third trimester. Unless there is an indication to perform a thirdtrimester obstetric sonogram, one will not be ordered; therefore, most diagnoses must be made after delivery. 10 For neonatal neuroimaging, 2D sonography offers a portable, lower cost examination without exposure to ionizing radiation. With the many advances that have been made, such as color Doppler, extended field of views, harmonic imaging, and high-resolution transducers, sonography is a particularly valuable technique to evaluate and follow up vascular anomalies such as VGAMs. 12,13 The most recent change for neonatal head sonograms is the implementation of 3D/4D sonography. This has proven to be extremely beneficial because it allows for volume sweeps of the entire cerebral anatomy and any pathology present. 12 A transfontanellar approach is the most common method for imaging neonatal heads. Common findings on the sonogram are multiple, hypoechoic tubular structures situated midline near the circle of Willis. Color Doppler will then show increased amounts of blood flow within this area. 8 Doppler flow patterns that are associated with a VGAM are (1) low-resistance arterial flow and (2) arterialized venous flow. 2 It is important for the sonographer to identify the feeding artery and draining vein anastomosis (nidus), as this will help direct the treatment for the malformation. Bartels 14 reviewed the followup in a 26-year-old patient in whom a 1-year followup postembolization of an AVM demonstrated a higher resistant vascular signal, which was interpreted as a decrease in the number of feeding arteries due to embolization. Griffith et al. 8 also reported a surgical approach that relied on Doppler findings: if a low-resistant signal was demonstrated, the surgeon was directed to continue dissection, and if a higher resistance Doppler flow signal was shown, then it was assumed that the procedure was successful. The higher resistant Doppler signal was believed to represent restoration of normal arterial flow passing through the surgical bed. Therefore, when sonographers perform follow-up examinations, they should look for a higher resistance signal in the artery and decreased pulsatility in the vein. The differential diagnoses for VGAM include holoprosencephaly, hematoma, choroid papilloma, and agenesis of the corpus callosum. 2,6 Other differentials include arachnoid cysts, porencephalic cysts, and choroid plexus cysts, but presence of color flow would eliminate these. 2,6,8,10 Vein of Galen malformation is always fatal if treatment is not initiated. Intense medical management for the cardiac failure is vital for patients survival. 7 By using medical treatment, intervention may then be put off until the infant is 5 to 6 months of age, which is the recommended time for invasive procedures to be done. 5,7,11 At that point, intervention is much safer and easier for these neonates. However, if the patient begins to deteriorate quickly, treatment may need to be performed earlier than 5 to 6 months. 5,11 Surgery has been proven to be very difficult in neonates because of the hypervascularity and frailty of the brain as well as limited access to the feeding vessels. 8,11 According to Griffith et al., 8 the morbidity and mortality rate is directly related to the size, which arteries and veins are involved, and what part of the brain is affected. Gray-scale and color Doppler can be very useful in localizing the vessels and confirming that the malformation has been completely removed. 8 Regrettably, this surgical ablation has very poor outcomes for the patient because of the invasiveness and brain injury. Treatment has greatly improved with the advances made in transcatheter percutaneous embolization. Survival rates reported with this form of endovascular management are 70% to 80%, and it has a cure rate of about 50%. 9 If treatment is required prior to 6 months of age, the timing of the first embolization depends on what symptoms the neonate presents with and how the patient responds to the medical therapy. 11 Embolization is performed via a catheter. The catheter is positioned into the femoral artery and, under sonographic guidance, is advanced until it reaches the vascular malformation. A metal coil is then placed

5 90 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY March/April 2010 VOL. 26, NO. 2 in the feeding artery, resulting in occlusion of the feeding vessel. 7 To achieve successful treatment, multiple procedures must be done over an extensive period of time. 7 The complications of embolizing a VGAM are perforating the feeding vessels or surrounding vessels or infarction. 9 Another complication that also has been reported by McElhinney et al. 9 is the migration of the coil into the malformation and possibly beyond. Although embolization is the preferred method of treatment, complete occlusion of the malformation is rarely obtained, and supplementary surgical clipping may then be necessary. In this case, the patient had received six coiling procedures by 3 months of age, and each one was successful in coiling off a segment of the malformation, although complete occlusion was not obtained. Prognosis for patients depends crucially on when the malformation is detected. The most severe types are often detected in utero. 2,6 Neonates have a reported mortality rate of 91.4%, 6 whereas infants with CHF and VGAM combined have a survival rate of only 8%. 2 VGAMs that are discovered later on in infancy have a variable prognosis, whereas those that are symptomatic in childhood or adulthood usually do very well. 2 Those who have treatment still have mortality rates ranging between 50% and 100%. 10 Conclusion Vein of Galen malformation is a serious, lifethreatening problem that usually results in a poor prognosis. The standard treatment is multiple coiling embolization procedures requiring imaging follow-up. This case report demonstrates the findings associated with serial neonatal head sonograms performed on a patient with a VGAM. The significance of understanding where the malformation is located and an attempt to identify the number of feeding vessels are very important in determining treatment plans. Sonographers also need to understand the hemodynamics associated with VGAM so that the examination can be tailored to demonstrate the success of the treatment. Specifically with effective embolization, the feeding artery develops a progressively higher resistant signal than the prior sonogram, and the draining vein develops decreased pulsatility. References 1. Ahuja AT, Antonio GE, Griffith GE, et al: Brain and Spine, in Ahuja AT, Antonio GE, Griffith GE, et al (eds): Diagnostic and Surgical Imaging Anatomy: Ultrasound. Salt Lake City, UT, Amirsys, 2007, p I Vandy ZK, Drose JA: Color flow detection of vein of Galen malformation in utero. J Diagn Med Sonography 1992;8: Gupta AK, Varma DR: Vein of Galen malformations: a review. Neurol India 2004;52: Hagen-Ansert SL: Neonatal echoencephalography, in Hagen-Ansert SL (ed): Textbook of Diagnostic Ultrasonography. 6th ed. St. Louis, MO, Elsevier, 2006, pp Bhattacharya JJ, Thammaroj J: Vein of Galen malformations. J Neurol Neurosurg Psychiatry Pract Neurol 2003;74: i42 i Liriano B, Levy R: Prenatal sonographic diagnosis of a vein of Galen aneurysmal malformation in a twin. J Diagn Med Sonography 2003;19: Center for Endovascular Surgery: Vein of Galen malformations vein-of-galen.asp 8. Griffith S, Pozniak MA, Mitchell CC, et al: Intraoperative sonography of intracranial arteriovenous malformations: how we do it. J Diagn Med Sonography 2004;23: McElhinney DB, Halbach VV, Silverman NH, Dowd CF, Hanley FL: Congenital cardiac anomalies with vein of Galen malformations in infants. Arch Dis Child 1998;78: Moore LE, Gonzales I, Brogdon K: Diagnostic challenge. J Diagn Med Sonography 2008;24: Mitchell PJ, Rosenfeld JV, Dargaville P, et al: Endovascular management of vein of Galen aneurysmal malformations presenting in the neonatal period. Am J Neuroradiol 2001;22: Riccabona M, Nelson TR, Weitzer C, Resch B, Pretorius DP: Potential of three-dimensional ultrasound in neonatal and pediatric neurosonography. Eur J Radiol 2003;13: Rumack CM, Drose JA: Neonatal and infant brain imaging, in Rumack CM, Wilson SR, Charboneau JW, Johnson JM (eds): Diagnostic Ultrasound. 3rd ed. St. Louis, MO, Elsevier Mosby, 2005, pp Bartels E: Evaluation of arteriovenous malformations (AVMs) with transcranial color-coded duplex sonography. J Ultrasound Med 2005;24: