2011-02-28-14 Online Continuing Medical Education: Vein of Galen aneurysm © www.TheFetus.net
Vein of Galen aneurysm: Online Continuing Medical Education
This course was jointly developed by Institute for Advanced Medical Education (IAME)
This activity has been planned and implemented in accordance with the Essential Areas and Policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the Institute for Advanced Medical Education and TheFetus.net. The Institute for Advanced Medical Education is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
The Institute for Advanced Medical Education designates this continuing medical education activity for a maximum of 1 Category 1 credit toward the AMA Physicians Recognition Award. Each physician should claim only those credits that he/she actually spent in the educational activity.
The American Registry of Diagnostic Medical Sonographers (ARDMS) accepts AMA Category 1 credits.
Course: Vein of Galen aneurysm
Faculty: Eva Leinart, MD., Philippe Jeanty, MD. PhD.
After completing this course, the participant should be able:
to recognize the diagnostic criteria for Vein of Galen aneurysm
to discuss with the parents the prognosis of the condition
to discuss differential diagnoses of the condition
Target audience: Physicians, sonographers and others who perform and/or interpret OB ultrasound.
Instructions: This Internet-based tutorial requires that you read through the text and related images in their entirety. You may read it from your browser or from hard copy after printing it out. In addition, it is suggested that you refer to references in the bibliography to reinforce the information presented by the author. Following completion of the tutorial, click on "Take the Quiz". After scoring a passing score of 70% or higher you will be taken to a secure payment page where you will have the opportunity to pay the CME fee and receive your certificate.
System requirements: In order to complete this program you must have a computer with a recent version of Internet Explorer or Netscape, and a printer, which is configured to print from the browser.
Volume Pricing: This course is $25.00 for 1 credit. You will receive your CME credits and certificate for this course. Four credit hours for $60.00. ($15.00 per credit). You will receive your credits and certificate for this course plus 2 vouchers which you can use immediately or at a future date. Eight credit hours are $80.00. ($10.00 per credit). You will receive your credit and certificate for this course plus 6 vouchers which you can use immediately or at a future date.
Customer Assistance: For any questions or problems concerning this program, or for problems related to the printing of the certificate, please contact IAME at 914-921-5700 or firstname.lastname@example.org
Estimated time for completion of tutorial: approximately 50 minutes
Date of review and release: March , 2011
Expiration Date: March , 2014
Disclosure: In compliance with the Essentials and Standards of the ACCME, the author of this CME tutorial is required to disclose any significant financial or other relationships they may have with the manufacturer(s) of any commercial product(s) or provider(s) of any commercial service(s) discussed in this program.
Drs. Leinart and Jeanty have indicated that they have no such relationships to disclose.
Vein of Galen aneurysm
Vein of Galen malformation
Vein of Galen aneurysm
Rare, incidence is unknown
Male to female ratio = 2:1
Vein of Galen malformation includes different arteriovenous fistulae located in the vicinity of the midbrain that vary from a single large aneurysmal dilatation of the vein of Galen to multiple communications between the vein and the carotid and vertebrobasilar systems [1,2]. There are 3 types described: arteriovenous fistula, arteriovenous malformation with ectasia of the vein of Galen and varix of the vein of Galen [3,4]. Both the ectasia and the varix appear to present later in life with bleeding episodes and do not present in the neonate with cardiac failure . Rarely, an aneurysm with a single feeder can exist . Arteriovenous fistulae associated with a varix are not part of the definition when they are located anywhere else in the brain .
Vein of Galen aneurysm is most common prenatally diagnosed cerebral vascular malformation. It causes 30% of vascular malformations presenting in the pediatric age group. It results from immaturity of the cerebral vascular system with persistence of the fetal vessel, median prosencephalic vein of Markowski which is a precursor of the vein of Galen. It develops between 7 -12 weeks of gestation when the median prosencephalic vein drains the large choroid plexuses. Median prosencephalic vein fails to regress and dilates and becomes aneurysmal due to a high blood flow. It prevents the development of the vein of Galen. It drains into the straight sinus or embryonic falcine sinus which usually persists in the absence of the straight sinus. So vein of Galen aneurysm is actually a dilation of the median prosencephalic vein of Markowski and not a dilation of the vein of Galen.
Vein of Galen aneurysm can be detected on the prenatal ultrasound. Most cases are detected in the third trimester.
Color Doppler is an important part of the ultrasound evaluation of any brain cystic lesion and should always be performed.
- Enlarged neck veins
Hydrocephalus can be caused by the compressed aqueduct, by venous hypertension which prevents appropriate resorption of the cerebrospinal fluid or due to cerebral atrophy.
Case 1: Images below show a case of a 30-year-old G2P1 who was scanned at 31 weeks of gestation for a suspected anomaly of the fetal head. The ultrasound examination showed a midline vascularized cystic structure. The location and Doppler signal suggested an aneurysm of the vein of Galen.
Arteriovenous shunting with the increased amount of the blood flow can significantly increase a venous return, cardiac preload and cause cardiomegaly and eventually cardiac failure with the fetal hydrops.
High-output heart failure started to develop. The fetal heart was enlarged and jugular veins dilated. Fetus developed a hydrops with ascites and hydrothorax. The findings were so severe that it unfortunately died after delivery .
Images 1-6: Images show a midline cystic structure (indicated by arrows), Doppler shows a strong blood flow within the mass.
Images 7,8: Image show cardiomegaly and enlarged neck veins, dilated jugular vein.
Images 9, 10: Images show dilated carotid artery and jugular vein.
Images 11, 12: Dilated jugular veins, due to a heart failure.
Case 2 : The following images show a vein of Galen aneurysm diagnosed in a fetus in 34th week of pregnancy .
Images 1, 2: 34 weeks of pregnancy; the image 1 represents a power Doppler transverse view of the fetal head showing the vein of Galen aneurysm. Image 2 shows flow within the sinus rectus.
Images 3, 4, 5, and 6: The images represent 3D power Doppler show angioarchitecture of the vein of Galen aneurysm and circle of Willis. (VGA - vein of Galen aneurysm).
Image 7: The image shows 3D power Doppler arterio-venous connections (arrows) between the circle of Willis and vein of Galen aneurysm.
Case 3: The following images were obtained during second trimester scan .
Images 1,2: Axial scans of the fetal head showing the dilated hypoechogenic vein of Galen in the midline and slightly dilated lateral ventricles.
Images 3,4: Power Doppler transverse images the fetal head showing dilated hypoechogenic vein of Galen in the midline.
Images 5,6: Power Doppler transverse images the fetal head showing dilated hypoechogenic vein of Galen in the midline.
: The images below show a case of the vein of Galen aneurysm obtained at 30 week of pregnancy. The baby died 11 hours after delivery because of cardiac insufficiency .
Third trimester fetus with a Vein of Galen aneurysm. The plain grayscale image demonstrates the centrally located aneurysm (a varix in fact, since this is a vein dilatation), and a small amount of ventriculomegaly .
Images 1, 2: Transverse scans of the fetal head at 30 weeks of pregnancy showing a central hypoechoioc structure (15 mm of width) representing aneurysm of the vein of Galen.
Images 3, 4: Color Doppler transverse scans of the fetal head at 30 weeks of pregnancy showing the blood flow in the aneurysm of the vein of Galen.
Images 5, 6: The pulsed Doppler showing the pulsations at the level of the aneurysm (image 5). Image 6 shows marked dilatation of the heart with a right predominence at the level of the four-chamber view.
This is a case of the fetus with a Vein of Galen aneurysm diagnosed in the third trimester. The plain grayscale image demonstrates the centrally located aneurysm and mild ventriculomegaly .
Images 1-3: Axial and coronal view if the aneurysm.
Images 4-9: Color and Power Doppler demonstrated the high amount of flow and turbulence and exquisitely demonstrates the feeder vessels.
Early prenatal management and close follow-up of the affected fetus is very important. It helps to an early detection of the associated complications such as cardiomegaly and congestive heart failure associated with fetal hydrops.
No data are available indicating the optimal mode of delivery of fetuses with aneurysm of the vein of Galen. If there are other associated anomalies such as severe porencephaly or cardiomegaly with hydrops, aggressive management is not indicated due to the high neonatal mortality (over 90% of neonate). Hydrocephaly may be an indication for an elective cesarean section. In the absence of associated anomalies we think that, to avoid possible damage during labor, an elective cesarean section can be performed but spontaneous delivery is possible.
Prognosis and treatment
In analyzing the clinical aspects of aneurysm of the vein of Galen, Amacher in 1973 identified three groups (neonatal, infantile and juvenile) based on the seriousness of the lesion and the age of the patient at the onset of symptoms . The severity of cardiomegaly and cardiac decompensation depends on the size and complexity of the vein of Galen aneurysm. During intrauterine life, the arteriovenous fistula maintains a low flow rate because of the low resistance of placental vascular bed; at delivery the changes of the blood circulation cause a sudden increase of flux through the fistula . If the aneurysm is small (less than 1 mm), the child may be asymptomatic at birth and the aneurysm may cause no relevant consequences for a long period of time. Later on, during infancy, adolescence or juvenile age, symptoms such as headache, seizure, visual disturbances, due to chronic hydrocephalus and/or subarachnoid or cerebral hemorrhages may occur. On the contrary, with a large aneurysm (greater than 20 mm), the great amount of blood circulating in the highflow fistula induces an overload of the venous circulation that can cause cardiomegaly, decompensation and hydrops. Therefore, an assessment of the cardiovascular system should be performed to identify early signs of cardiac insufficiency, to establish the time and the type of delivery, and to prepare an adequate assistance for the newborn. A careful prenatal ultrasound examination allows the neurosurgeon to plan the best neuroradiological and surgical management according to the type of vein of Galen aneurysm and the status of the patient.
There is no known in utero treatment. Cardiac failure may develop after the delivery and can be a cause of death in case the vein of Galen aneurysm is not treated. The prognosis much improved with the endovascular embolization techniques which have better outcome than surgical treatment. The aim is to reduce the shunt flow and prevent congestive heart failure and chronic cerebral hypertension .
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