Special Report

Vein of Galen Aneurysms: A Review and Current Perspective

Michael Bruce Horowitz, Charles A. Jungreis, Ronald G. Quisling, and lan Pollack

The term vein of Galen aneurysm encom­ the internal cerebral vein to form the vein of passes a diverse group of vascular anomalies Galen (4). sharing a common feature, dilatation of the vein Differentiation of the venous sinuses occurs of Galen. The name, therefore, is a misnomer. concurrently with development of arterial and Although some investigators speculate that vein venous drainage systems. By week 4, a primi­ of Galen aneurysms comprise up to 33% of gi­ tive capillary network is drained by anterior, ant arteriovenous malformations in infancy and middle, and posterior meningeal plexi (3, 4). childhood ( 1), the true incidence of this a nom­ Each plexus has a stem that drains into one of aly remains uncertain. A review of the literature the paired longitudinal head sinuses, which in reveals fewer than 300 reported cases since turn drain into the jugular veins ( 3, 4). Atresia of Jaeger et al 's clinical description in 1937 (2). the longitudinal sinuses leads to the develop­ As we will outline below, our understanding of ment of the transverse and sigmoid sinuses by the embryology, anatomy, clinical presentation, week 7 (3, 4). At birth only the superior and and management of these difficult vascular inferior sagittal, straight, transverse, occipital, malformations has progressed significantly and sigmoid sinuses remain, along with a still over the past 50 years. plexiform torcula (3, 4). On occasion, a tran­ sient falcine sinus extending from the vein of Embryology and Vascular Anatomy of the Galen to the superior sagittal sinus is seen ( 4). Vein of Galen Such sinuses represent persistent intradural channels located within the falx cerebri. The development of the human cerebral vas­ Under normal circumstances, the mature cular system is complex; a thorough analysis vein of Galen persists as a bridge between the has been conducted by Padget (3) . Cerebral deep parenchymal venous system and the ve­ vascularization begins during gestational week nous sinuses. As such, it serves as a conduit 4, at the time of neural tube closure. By the end between the internal cerebral veins, basal veins of week 5, the choroidal and quadrigeminal ar­ of Rosenthal, precentral cerebellar vein, ver­ teries, the main afferents to the vein of Galen, mian veins, and straight sinus (5). are well developed ( 4). During week 6 the circle Lying within the subarachnoid space in an of Willis is completed. The anterior cerebral ar­ area known as the great transverse cleft, the tery supplies the choroid plexus of the lateral vein of Galen is bordered superiorly by the free ventricles, and the middle cerebral artery sup­ margin of the falx, posteriorly by the tentorium plies the striatum (4). Meanwhile, at the roof of cerebelli, anteriorly and inferiorly by the roof of the diencephalon, the median prosencephalic the third ventricle, and laterally by the choroidal vein, or primitive internal cerebral vein, devel­ fissures of the lateral ventricles ( 4) (Fig 1). ops as the main draining structure for the telen­ cephalic choroid plexus. By week 10 the me­ Arterial Supply dian prosencephalic vein is largely replaced by the paired internal cerebral veins, which then In a series of 23 patients with vein of Galen become the predominant means of choroidal aneurysms, Raybaud et al found the posterior drainage (4). Although the median prosen­ choroidal arteries to be the primary feeders ( 4). cephalic regresses, its most caudal portion joins The anterior cerebral arteries were the second

From the Departments of Neurosurgery (M.B.H., C.A.J. ) and Radiology (C.A.J.}, University of Pittsburgh Medical Center; Department of Neurosurgery, Children's Hospital of Pittsburgh (I.P.}; and Department of Radiology, University of Florida , Gainesville (R.G.Q.). Address reprint requests to Michael Bruce Horowitz, MD, University of Texas Southwestern Medical Center, Division of Neuroradiology, Department of Rad iology, 5323 Harry Hines Blvd, Dallas, TX 75235-8896. Index terms: Vein of Galen; Veins, abnormalities and anomalies; Arteriovenous malformations, cerebral; Special reports AJNR 15:1486-1496, Sep 1994 0195-6108/ 94/ 1508-1486 © American Society of Neuroradiology 1486 AJNR: 15, September 1994 VEIN OF GALEN 1487

Fig 1. Midsagittal section of the bra in il­ lustrating the large thrombosed vein of Galen aneurysm (open arrows) overlying the cerebellum and the collicular plate. The ventricles are distended with recent hem or­ rhage. Multifocal subarachnoid hem orrhage is also seen. Ye llow streaks represent a postmortem attempt at perfusing the arter­ ies with yellow silicone. Note the sm all size of the brain and cerebellum. White fibrotic meninges cover the m edial occipital lobe adjacent to the m alformation (curved ar­ row). (Courtesy of Dr M. A . Barmada, Chil­ dren's Hospital of Pittsburgh.}

most commonly involved vessels, generally superior sagittal sinus, blood flowed posteriorly providing bilateral blood supply. The anterior into the torcula and then into one transverse thalamoperforators were common secondary sinus. Some blood, however, flowed anteriorly tributaries, joining primary afferents at the level within the superior sagittal sinus, entered a sec­ of the choroidal fissure. Perimesencephalic ves­ ond falcine sinus, which angiographically sels were constantly involved in neonates and seemed to cross the first (in a separate dural frequently involved in older children. Distal sheet), and finally discharged into the torcular branches of the posterior cerebral arteries and or other transverse sinus. In these situations posterior thalamoperforators supplied the mal­ blood may drain via petrosal and tentorial ve­ formations in a moderate number of neonates. nous channels into the cavernous sinus. Falcine In approximately 50% of patients, the menin­ sinuses were generally associated with high­ geal arteries were significant. flow shunts. Five of Raybaud's cases revealed angiographic absence of straight, falcine, trans­ Venous Drainage verse, and sigmoid sinuses with stasis of con­ trast within the sacs and lack of jugular vein In healthy persons the vein of Galen drains opacification. In terms of nonsinus venous the internal cerebral veins, basal vein of drainage, the authors at no time demonstrated Rosenthal, posterior mesencephalic vein, supe­ dilatation of the internal cerebral veins, al­ rior vermian vein, precentral cerebellar vein, though they did see retrograde flow in these and superior cerebellar veins (5). Sixty-eight structures. Large choroidal veins and an en­ percent of Raybaud's patients had major ve­ gorged subependymal system drained into the nous anomalies including absent or interrupted basal veins, uncal veins, and cavernous si ­ straight sinuses, straight sinuses divided into nuses. Lateral mesencephalic venous drainage two segments, and straight sinuses judged too entered the transverse sinus. small in relationship to the sacs (4) . A small number of patients demonstrated both falcine and patent straight sinuses. An equally small Categorization number presented with falcine loops. This ar­ rangement consisted of a falcine sinus draining Yasargil divides vein of Galen aneurysms into the sac into the superior sagittal sinus. From the four categories (6). Type 1 contains pure fistu - 1488 HOROWITZ AJNR: 15, September 1994

las between arteries and the vein of Galen with venous aspect of the malformation. In grade 1 the nidus of the lesion being the ampulla of the venous structure, the degree of ectasia of the vein. This entire lesion is extrinsic to the brain straight sinus is proportional to that of the vein parenchyma. Type 2 is composed of thalam­ of Galen, with both being only minimally en­ operforators that travel through normal paren­ larged. Grade 2 structure occurs when the vein chyma and supply both brain tissue and give of Galen is more dilated than the straight sinus, branches to the vein of Galen. These lesions are with both structures moderately increased in both intrinsic and extrinsic to the central ner­ size. Grade 3 lesions demonstrate marked dila­ vous system. Type 3 malformations are mixed tation of both structures, and grade 4 have sig­ lesions with characteristics of both type 1 and nificant enlargement of the veins of Galen with type 2 lesions. Type 4 lesions have malforma­ normal, stenotic, or absent straight sinuses (7). tions proximal to the vein of Galen aneurysms These angiographic findings correlated well that drain into veins that then empty into the with measurements of venous pressure within veins of Galen. the malformation. Whereas the mean venous A further modification of these classifications pressure within Galenic aneurysms in individu­ has been provided by Quisling and Mickle, who als with venous restrictions was 40 em of water, categorized Galenic vascular malformations on the pressure in patients without venous restric­ the basis of several factors: nidus complexity, tions averaged 25 em of water (3). These an­ afferent supply, and efferent drainage patterns giographic findings and pressure measure­ (7) . Type 1 consists of "true" Galenic fistulas ments were related in a logical way to a number with direct arteriovenous communication via a of clinical features. For example, no patient with unilateral, choroidal arterial trunk. As it ap­ obstructed drainage was in cardiac failure at the proaches the vein of Galen aneurysm this trunk time of presentation, thus confirming that some can be divided into as many as five smaller measure of cardiac protection is provided by distal branches. When an angiomatous matrix is restriction of venous outflow from the malfor­ present it is usually less than 1 em in greatest mation. Conversely, no case in which the effer­ diameter and is typically in direct continuity ent venous pressure was less than 20 em of with the Galenic aneurysm. Type 2 Galenic fis­ water had brain calcifications, implicating ele­ tulas are actually "ordinary" deep arteriovenous vated venous pressure in the development of malformations located within the thalamus the finding. Finally, grade 4 patients with severe and/or hypothalamus. They are supplied by the outflow restriction were more likely to undergo thalamoperforating arteries and drain via the spontaneous thrombosis of their malformations, superior thalamic veins and Galenic system. Ar­ which suggests that a lower flow rate is present teriovenous malformation (AVM) matrix size in in those fistulas that have high-grade efferent such cases ranges from 1 to 2 em in greatest stenosis. Taken together, these observations diameter. Type 3 Galenic vascular malforma­ provided the rationale for initial attempts to tions are similar to type 1 fistulas but have sig­ treat Galenic malformations via the venous nificantly more afferent vascular complexity. In­ route particularly in patients with high-output stead of single feeding arteries, type 3 cardiac failure. malformations are supplied by both anterior and posterior choroidal arteries and the persis­ Developmental Theory tent embryonic remnants of the distal anterior cerebral arteries. The authors observed that Raybaud proposes that vein of Galen aneu­ their angiographic distinctions correlated with rysms are not a result of dilatation of the veins of the clinical presentation of the lesion. For ex­ Galen, but rather a consequence of dilatation of ample, no patients in categories 1 or 2 had overt persistent median prosencephalic veins. The cardiac decompensation (7), whereas the type evidence he cites supporting this statement in­ 3 Galenic fistulas, which as a group exhibited cludes the following: (a) the vein of Galen de­ the most shunting, were more likely to present velops late and lacks connections to the choroi­ with high-output cardiac failure in the newborn dal branch of the anterior cerebral artery, which period. is a primary feeder in most vein of Galen aneu­ In addition to categorizing the arterial supply rysms; (b) the typical vein of Galen aneurysm to the vein of Galen aneurysm, these authors directly drains both prosencephalic and mesen­ also favored using a grading system for the cephalic arteries in a pattern typical of the me- AJNR: 15, September 1994 VEIN OF GALEN 1489 dian prosencephalic vein, but the normal ma­ age who present with headaches, exercise syn­ ture vein of Galen does not ( 4). Anomalous copes, and subarachnoid hemorrhage ( 1 0). In venous drainage as described in previous sec­ addition, certain presenting signs such as visual tions probably represents persistent fetal drain­ deterioration, proptosis, seizures, hemiparesis, age that remains intact because it effectively developmental retardation, facial vein enlarge­ deals with the high-flow system ( 4). Such per­ ment, epistaxis, and vertigo do not necessarily sistent fetal drainage may prevent the develop­ coincide with age-related groupings. Nonethe­ ment of the normal sinus system (4). Alterna­ less, the above classification schema provides a tively, persistent falcine sinuses may be a useful basis for categorizing patients with vein consequence of straight sinus occlusion early in of Galen aneurysms. the developmental period (4) . Lasjuanias et a! have proposed additional theories concerning the development of vein of Congestive Heart Failure Galen aneurysms (8). They agree that these Congestive heart failure is the major cause of aneurysms may develop secondary to proximal mortality and morbidity in neonates and infants angiomatous malformations. However, they harboring vein of Galen aneurysms. In severe also point out the frequency of sinus obstruction cases, as much as 80% of left ventricular output (especially the straight sinus) associated with may be delivered to the head as a consequence vein of Galen malformations, thus speculating of the low vascular resistance within the malfor­ that increased resistance to outflow at an early mation (12). Because this output returns di ­ stage may lead to proximal venous ectasia. rectly to the right ventricle, right heart failure These authors felt that venous agenesis was a from volume and work overload may ensue. more likely mechanism of outflow obstruction Myocardial ischemia is further promoted by de­ than was sinus thrombosis, because acquired creased afterload induced by the AVM . Conse­ thrombosis usually fails to produce subsequent quent reduction in diastolic pressures jeopar­ vein of Galen aneurysms. Mayberg and dizes myocardial perfusion (8) . Other cardiac Zimmerman, however, have reported a case of anomalies reported in association with vein of a 64-year-old man with a dural AVM, vein of Galen aneurysms include transposition of the Galen aneurysm, and straight sinus thrombosis great vessels and aortic stenosis ( 13, 14). (9), and contend that the straight sinus throm­ Heart failure generally presents not before, bosis was the primary event leading to the de­ but shortly after birth. The explanation for this velopment of both vascular abnormalities. may reside in the fact that in utero, the pla­ centa's low vascular resistance reduces the Clinical Presentation amount of blood, which is "stolen" by the ab­ normal, low-resistance cerebral shunt (12). On The association in neonates of intractable examination, the neonate or infant with cardiac congestive heart failure and a cranial bruit pro­ decompensation from a vein of Galen aneurysm vides the most striking manifestation of vein of may manifest cyanosis, decreased peripheral Galen aneurysm; however, less fulminant pulses, and in some cases audible cranial bruits modes of presentation are the norm in older (12). In the absence of an obvious bruit, the infants, children, and adults. Although attempts correct diagnosis initially may be missed unless have been made to subdivide clinical presenta­ a high index of suspicion is maintained. tion on a strictly age-related basis, it is readily apparent that, between age groups, signs and symptoms overlap (10, 11). For example, in Hydrocephalus Amacher and Shillito's classification schema, group 1 consists of neonates with cranial bruits The etiology of hydrocephalus is multifacto­ and severe congestive heart failure; group 2 rial and includes Sylvian aqueduct obstruction, consists of neonates and infants with mild heart resorptive blocks, hydrocephalus ex vacuo (a failure who develop craniomegaly and cranial consequence of encephalomalacia and cerebral bruits within 1 to 6 months. Group 3 comprises atrophy [15]) , and abnormal transependy­ children 1 to 12 months old with craniomegaly mal cerebrospinal flu id resorption. Resorptive and cranial bruits, but no heart failure; and blocks may be attributable to increased pres­ group 4 consists of persons 3.5 to 27 years of sure within the sagittal sinus ( 7, 8). 1490 HOROWITZ AJNR: 15, September 1994

Developmental Retardation like, compressible skin lesions composed of Developmental retardation is common with blood-filled venous and cavernous angiomas. vein of Galen aneurysms and is often used as an Whether the association of these diseases with argument against offering treatment to severely vein of Galen aneurysms is a chance occur­ affected infants. Mechanisms implicated for rence is not known at this time. Other malfor­ such damage are arterial steal, ischemia caused mations reported in association with vein of by compression from engorged draining veins Galen aneurysms include supernumerary digits, and an enlarged vein of Galen, and increased hypospadias, transposition of the great vessels venous pressure with subsequent venous infarc­ (28), and aortic stenosis (13, 14). tion after spontaneous, partial, or complete an­ eurysm thrombosis (7, 8, 16). Grossman et al Evaluation and Diagnostic Studies recognized the role of arterial steal after noting Ultrasound resolution of optic disc pallor in two patients undergoing vein of Galen aneurysm excision Ultrasound is an excellent method of screen­ (17). They concluded that early surgery might ing for and evaluating vein of Galen aneurysms, abort ischemic brain damage in those fortunate both in utero and during the neonatal period enough to be born with normal parenchyma. ( 29-31). Ultrasonic demonstration of vascular pulsations helps differentiate vein of Galen an­ Failure to Thrive eurysms from other possible midline structures (30) (Figs 2 and 3). Color Doppler ultrasound Many neonates and infants with vein of Galen permits the characterization of blood flow within aneurysms fail to thrive. Cardiac decompensa­ the malformation and, although useful in delin­ tion undoubtedly plays a tremendous role in eating feeding and draining vessels, is espe­ such failure. However, hypothalamic and hy­ cially valuable in evaluating the effectiveness of pophyseal dysfunction secondary to venous therapy (32, 33). congestion within these structures also must be considered a potential mechanism (8). Chest Radiographs

Vein of Galen Aneurysms Thrombosis Chest radiographs may reveal cardiomegaly with right-sided chamber enlargement, widen­ Spontaneous thrombosis of vein of Galen an­ ing of the superior mediastinum, retrosternal eurysms may be heralded by the development fullness, posterior displacement of the upper of obstructive hydrocephalus or by the onset of trachea, and retropharyngeal soft tissue promi­ intraventricular hemorrhage (18 -24). Heinz et nence caused by encroachment on this space al, the first to describe thrombosis of a vein of by dilated carotid arteries and jugular veins Galen aneurysm, felt it occurred in utero or dur­ (34). ing birth (20). However, later reports clearly indicated that thrombosis could take place Skull Radiographs throughout infancy and, in some cases, in adult­ hood (18, 25). There is no typical presentation Radiographs of the skull are of minimal utility of thrombosed vein of Galen aneurysm except in the diagnosis and evaluation of suspected the nearly ubiquitous presence of hydrocepha­ vein of Galen aneurysms. Occasionally they lus and its attendant signs and symptoms. demonstrate rims of calcium corresponding to a calcified aneurysm sac (35). Associated ILLnesses Computed Tomography (CT) Both Turner syndrome and blue rubber bleb nevus syndrome have been reported to occur in CT images of vein of Galen aneurysms gen­ conjunction with vein of Galen aneurysms (26, erally reveal round masses lying in the quadri­ 27). The former involves the absence of a single geminal cistern behind the posterior border of X chromosome in female patients and has been an anteriorly displaced third ventricle (Fig 4A). associated with other vascular anomalies in­ High density within the lesion may suggest vein cluding coarctation of the aorta and pulmonic of Galen aneurysm thrombosis (5, 22, 36). Af­ stenosis. The latter presents with blue, nipple- ter administration of contrast, dense, homage- AJNR: 15, September 1994 VEIN OF GALEN 1491

Fig 2. Sagittal-view head ultrasound revealing a dilated lat­ Fig 3. Axial -view head ultrasound with dilated lateral ventri­ era l ventricle (small arrow), a dilated and anteriorly displaced cles (small arrows) and a midline vein of Galen aneurysm (larg e third ventricle (curued arrow), and a vein of Galen aneurysm arrow). (large arrow). neous opacification of both the vein of Galen ever, MR has not obviated the need for catheter aneurysm and the adjacent tentorial vessels and angiography, especially when intervention is draining sinuses is seen (5, 36) (Fig 4, B and planned (38, 39). MR angiography, on the other C) . When the malformation is thrombosed con­ hand, has begun to provide substantial insight trast tends to enhance the aneurysm wall and into the anatomy of many vascular diseases and opacify small zones within the aneurysmal with improvement may become the primary pouch (5, 36). A "target sign" has been de­ tool for the evaluation of vein of Galen aneu­ scribed in this circumstance. Calcification of the rysms. malformation wall, seen in approximately 14% of patients, is rarely seen in patients younger Angiography than 15 years of age ( 18). Cerebral parenchy­ mal calcifications are generally attributed to Angiography remains the standard of refer­ ischemia especially when located in watershed ence for the evaluation of vein of Galen aneu­ regions and, as such, may be an index of cere­ rysms (Fig 4, D and E). bral damage. Treatment Magnetic Resonance (fVJR) and fVJR The primary indication for treating neonates Angiography with vein of Galen aneurysms is congestive The ability of MR to image noninvasively in heart failure refractory to medical treatment. sagittal, coronal, and axial planes makes it an Surgery or endovascular treatment can in many invaluable tool in the characterization of arterial cases be postponed by medical care until the afferents, venous drainage, malformation posi­ child is older, at which point intervention is safer tion and size, and appearance of surrounding and easier. In those patients requiring invasive brain. MR allows the early identification of sinus treatment, the goal of therapy is not necessarily abnormalities and venous drainage patterns, the complete obliteration or extirpation of the which not only facilitates therapeutic planning aneurysms, but rather the arrest of congestive of transvenous or transtorcular endovascular heart failure. Relative contraindications to treat­ approaches, but also helps guide the angiogra­ ment include medi cally controlled congestive pher toward the most important vessels for heart failure or uncontrollable systemic failure. study (37). This is particularly critical in neo­ Finally, imaging evidence of brain damage has nates in whom venous access is difficult, and been considered a contraindication by some total acceptable contrast loads are low. How- (40). 1492 HOROWITZ AJNR: 15, September 1994

D E F

Fig 4. Neonate with a vein of Galen aneurysm. A, Contrast-enhanced axial head CT scan revealing a 2.5-cm midline vein of Galen aneurysm anteriorly displacing the third ventricle with accompanying hydrocephalus. 8, Contrast-enhanced axial head CT in the same patient demonstrating an enlarged straight sinus. C, Contrast-enhanced axial head CT more superiorly demonstrating the extensive surrounding vascular plexus. 0 , Lateral internal carotid artery angiogram revealing the anterior cerebral artery (Large arrow), anterior choroidal artery (small arrow), and posterior choroidal artery (curued arrow) supply to the vein of Galen aneurysm. E, Lateral angiographic view showing aneurysm drainage via enlarged falcine, transverse, and sigmoid dural sinuses. Notice that the junction of the falcine sinus with the superior sagittal sinus is not at the torcula. F, Lateral angiogram via superselective catheterization of posterior circulation. Posterior choroidal artery supply is opacified. Prominent venous drainage via the straight sinus is apparent. G, Lateral angiogram displaying transvenous approach with the catheter (arrow) in the sinus system and the catheter tip in the vein of Galen aneurysm. Some coils have been deposited in the aneurysm. H, Lateral skull radiograph demonstrating minicoils within both the vein of Galen aneurysm and the right pericallosal artery. A transvenous approach had been used for coil deposition in the aneurysm, and a transarterial approach had been used for coil deposition in the pericallosal artery. I, Lateral view of a right posterior cerebral artery angiogram demonstrating residual posterior choroidal artery supply to the vein of Galen aneurysm. Endovascular coils have been deposited in the aneurysm and the anterior pericallosal artery. The flow through the malformation has been decreased sufficiently by the coils to resolve the congestive heart failure in this infant. AJNR: 15, September 1994 VEIN OF GALEN 1493

Surgery shunts placed at surgery. The authors felt that Jaeger et al performed carotid ligation in an all patients requiring shunts should have cath­ attempt to control the degree of blood flow eters placed before malformation ablation, be­ through a Galenic malformation (2). This pro­ cause after ablation the subependymal ve ins may become distended and thus possibly prone cedure provided no clear protection against fur­ to rupture if a catheter is passed through the ther cardiovascular compromise and eventual ventricular wall (42). Distended ependymal death. Subsequent to that initial case report, veins, however, may be present before malfor­ numerous other reports have described surgical mation ablation, and the risks of shunt place­ approaches to Galenic malformations (6, 11 , ment may be high at this time as well. 15, 41, 42). Certain issues must be considered In many patients, particularly those with ob­ before undertaking any planned ablative proce­ structive hydrocephalus secondary to throm­ dure. The delicacy of the poorly myelinated bosed vein of Galen aneurysms, cerebrospinal neonatal brain makes the retraction necessary fluid shunting is the only therapy required (21 ). to visualize and treat the vein of Galen aneu­ In such patients, attempts to resect the throm­ rysm adequately and its arterial supply poten­ bosed aneurysm sacs have been associated tially more dangerous than in older children. with unacceptable morbidity (20-23, 25, 42). Moreover, the risk of life-threatening blood loss is accentuated in such patients because of their limited blood volumes. Accordingly, where fea­ Endovascular Approaches sible, every attempt should be made to treat Advances in catheter design and emboliza­ such lesions nonsurgically in this age group tion materials have brought neuroradiologic en­ with the thought that if surgery is required, it can dovascular approaches to the forefront of ther­ be undertaken more safely in an older patient. apeutic options in treatment of vein of Galen Theoretical risks of normal perfusion pres­ aneurysms. Berenstein et al's indications for sure breakthrough must be considered when embolization include: (a) preoperative oblitera­ planning any treatment of vascular malforma­ tion of less surgically accessible feeding vessels tion. After obliteration of some vascular malfor­ in the hope of reducing surgical morbidity; (b) mations, previously hypoperfused peripheral postoperative obliteration of smaller feeding brain tissue has increased blood flow. Sudden vessels after surgical ligation of major arterial increases in blood flow to these regions has suppliers; and (c) definite therapy of vein of been reported to result in brain swelling, hem­ Galen aneurysms using a staged technique orrhage, and seizures (43, 44). Normal perfu­ (47). Lasjaunias et al have made an important sion pressure breakthrough has been associ­ distinction in their discussions of endovascular ated with malformations greater than 4 em in treatment of vein of Galen aneurysms. In those largest dimension, angiograms showing steal, patients with vein of Galen aneurysms second­ and individuals with possible steal-related neu­ ary to a parenchymal or choroidal AVM, they rologic deficits ( 45). Many surgeons and inter­ emphasize the necessity of avoiding venous ventionalists, therefore, feel that staged treat­ embolization. Approaches to such malforma­ ment of complicated Galenic malformations tions should be from the arterial side to avoid should be considered, especially when the venous hypertension and congestion and their above-mentioned risk factors are present. associated morbidity and mortality (40) . The need for and timing of ventricular drain­ Various techniques have been described for age in conjunction with primary treatment of obliteration of vein of Galen aneurysms, includ­ vein of Galen aneurysms remains controversial. ing transarterial, transvenous, and transtorcular Schneider et al have described a number of embolization (8, 40, 47-52) (Fig 4, F- 1) . The complications associated with ventriculoperito­ specific endovascular approach has depended neal shunts in children with hydrocephalus and on the specific anatomy of the given case. Ar­ vein of Galen aneurysms. These included status teriovenous fistulas can be occluded on the ar­ epilepticus, intraventricular hemorrhage, sub­ terial side from either a transarterial or trans­ dural collections, and new neurologic deficits venous approach using embolic agents such as (46). In Yasargil et a) 's series two postoperative coils, acrylics ( cyanoacrylates), and endovas­ deaths were heralded by intraventricular hema­ cular balloons. Fistulas pose the technical chal­ tomas in hydrocephalic patients who had lenge of depositing emboli at the site of the 1494 HOROWITZ AJNR: 15, September 1994 shunt in such a way as to maintain their posi­ 20 years). Of these patients, 110 presented with tions. High-flow fistulas are notorious for trans­ congestive heart failure, 94 with increased in­ mitting even large emboli to the venous side tracranial pressure, 57 with cranial bruits, 37 and to the pulmonary circulation with fatal re­ with focal neurologic deficits, 26 with seizures, sults. As a consequence of such pass-through and 25 with hemorrhage (41). Ninety-one pa­ phenomena, venous occlusion therapy has tients underwent direct surgical treatment; 29 gained popularity. In cases of multiple fistulas received shunts and remote vessel ligation; 46 converging on the vein of Galen, the trans­ had medical treatment alone; and 79 had no venous and transtorcular approaches have even therapy or no details of therapy in their reports. more appeal. The goal in these approaches is to Overall mortality was 55.6% with 37.4% mortal­ occlude the outflow in the vein of Galen, thus ity for surgical cases and a 46.3% incidence of inducing retrograde thrombosis and obliteration significant morbidity in postoperative survivors. of the fistulas. Many embolic agents have been Neonates had 91.4% surgical mortality, which used, although coils are currently the primary approximated the nonsurgical outcome. The 1- agents used in this approach. Complete cure is to-12-month age group suffered 31.7% surgical not usually required, and partial occlusion of the mortality, and the older-than-1-year age group dilated vein frequently reverses the cardiovas­ had 25.6% surgical mortality and 42.3% major cular compromise (Ron Quisling, personal morbidity. Yasargil's series consisting of 70 pa­ communication). tients showed 67% neonatal (younger than 1 When approaching these lesions from a month old) postoperative mortality, 40% infant transarterial route with primary arterial emboli­ (1 to 24 months old) postoperative mortality, zations, the interventionalist must be aware of and 27% child and adult postoperative mortality the risks of normal perfusion pressure break­ (6). Total survival in this series of patients op­ through. Mickle and Quisling tried to avoid nor­ erated on and not operated on was 1 0% for mal perfusion pressure breakthrough by reduc­ neonates, 4 7% for infants, and 56% for children ing blood flow 50% in stage 1 and then returning and adults. An inescapable conclusion from 3 to 21 days later, if necessary, to eliminate these studies, which include cases Spanning completely all residual flow (51). If total oblit­ many eras of neurosurgical, medical, and radio­ eration could not be achieved, embolization was logic advances, is that neonates have pro­ aimed at stabilizing the patient's cardiovascular foundly worse outcomes than other age groups, status in the hope of converting a neonate or most likely as a consequence of cardiac de­ infant into an older-age-group member in whom compensation with resultant multisystem fail­ surgery or embolization has a better outcome ure. (47). Fortunately, in the current era of endovascu­ An unusual but potentially fatal complication lar therapy, morbidity and mortality rates have of endovascular therapy is a consumptive improved. Lasjaunias et al have reported 36 coagulopathy manifested by a precipitous cases treated by endovascular approaches postembolization thrombocytopenia that is fol­ (78% pediatric, 22% adult) with a mortality of lowed by intracranial hemorrhage. The cause of 13% (40). Casasco et al reported 100% survival such coagulation abnormalities may rest in the in seven infants treated via transvenous embo­ rapid deposition of large amounts of thrombus lization (54). Dowd et al reported transvenous within the recently treated vascular anomaly. approaches to the venous and/or arterial sides As in the related Kasabach-Merritt syndrome of vein of Galen aneurysms in three neonates (53), treatment consists of clotting factors and who survived and were stable at 9 to 12 months platelet replacement. follow-up (52). Mickle's experience with tran­ storcular embolization in 15 infants and older Outcome children and 9 neonates was favorable. Forty­ four percent of the latter and 93% of the former Johnston et al reviewed 232 cases of vein of survived (55). Lylyk et al used endovascular Galen aneurysms reported in the literature be­ therapy in 28 children. Forty-five percent of fore 1987 and recorded cases involving 80 ne­ those younger than 1 year of age had good onates, 82 infants ( 1 to 12 months of age), 39 outcomes; 61.5% of those ages 1 to 2 years had children ( 1 to 5 years), 22 children and young good outcomes, and 100% of those older than 2 adults ( 6 to 20 years), and 22 adults (older than years had good outcomes (56). AJNR: 15, September 1994 VEIN OF GALEN 1495

Summary and Conclusions 4. Raybaud CA, Strother CM, Hald JK. Aneurysms of the vein of Galen: embryonic considerations and anatomical features relating Our approach to treating a patieAt with a vein to the pa thogenesis of the malformation. Neuroradiology 1989; of Galen aneurysm is, of course, influenced 31 :1 09-128 greatly by the age of the patient, the clinical 5. Skirkhoda A, Wha ley RA, Boone SC, Scatliff J H, Schnapf D. Varied CT appea rance of aneurysms of the vein of Galen in in­ symptoms, and the angiographic architecture fancy. Neuroradiology 1981 ;21 :265-270 of the malformation. Therapeutic options are 6. Yasargil MG. Microsurgery 1118. New York: Theme Medical Pub­ primarily based on whether a true AVM is lishers, 1988:323-357 present or if the malformation represents an 7. Quisling RG, Mickle JP. Venous pressure measurements in vein of Galen aneurysms. AJNR Am J Neuroradiol1989; 10:411-417 arteriovenous fistula involving the vein of Galen. 8. Lasjaunias P, Ter Brugge K, Lopez lbor L, et al. The ro le of dural Arterial endovascular approaches, microneuro­ anomalies in vein of Galen aneurysm s: report of six cases and surgery, and/or radiosurgery are preferred for review of the literature. AJNR Am J Neuroradio11987;8: 185-192 management of the former; the transvenous en­ 9. Mayberg MR , Zimmerman C. Vein of Ga len aneurysm associated with dural AVM and straight si nus thrombosis: case report. J dovascular approach has become the corner­ Neurosurg 1988;68:288-291 stone of treatment in the latter. The most critical 10. Amacher A L, Shill ito J Jr. The syndromes and su rgical treatment group, however, is the neonates in extreme car­ of aneurysm s of the great vein of Galen. J Neurosurg 1973;39: diovascular distress. In this case our therapeutic 89-98 11. Hoffman HJ, Chuang S, Hendrick EB, Humphreys RP. Aneurysms intervention is initially endovascular from the of the vein of Ga len: experience at the Hospital for Sick Ch ildren, venous side, either transfemoral or transtorcu­ Toronto. J Neurosurg 1982;57:316-322 lar. The immediate goal is to increase resistance 12. Pellegrino PA, Milanesi 0 , Saia OS, Carollo C. Congestive heart to right ventricular output. Advantages of this failure secondary to cerebral arterio-venous fistula. Childs Nerv Sys£ 1987;3:141-144 approach over a transarterial approach include 13. Gom ez JR, Whitten CF, Nolke A, Bernstein J, Meyer JS. Aneu­ a shorter anesthesia time, minimal fluid and/or rysmal malfo rmation of the great ve in of Galen causing heart contrast administration, and creation of a wire fa ilure in early infancy. Pediatrics 1983;31 :400 "basket" or "bird's nest" on the venous side that 14. Hirano A, Solomon S. Arteriovenous aneurysm of the vein of Galen. Arch Neuro1 1960;3:589 helps prevent emboli that may be deposited on 15. Rosenfeld J V, Fabinyi GC. Acute hydrocephalus in an elderly the arterial side in subsequent embolizations woman with an aneurysm of the vein of Galen. Neurosurgery from passing through the malformation. The 1984; 15:852- 854 16. Norman MG , Becker LE. Cerebral damage in neonates resulting transvenous approach can be easily repeated from arteriovenous malformation of the vein of Galen. J Neural multiple times and may be supplemented by Neurosurg Psychiatry 1974;37:252-258 transarterial embolizations. Endovascular coils 17. Grossman Rl, Bruce DA, Zimmerman RA, Goldberg HI , Bilaniuk have been the mainstay for such venous embo­ LT. Vascular steal associated with vein of Galen aneurysm. Neu­ lizations. The end point of treatment is not com­ roradiology 1984;26:381- 386 18. Chapman S, Hockley AD. Calcification of an aneurysm of the vein plete occlusion of the fistula but improvement in of Galen. PedialrRadio1 1989;19:541-542 cardiac function. Often, more than one stage is 19. Dean DF. Management of clotted aneurysm of the vein of Galen. required to reach our goal. Neurosurgery 1981 ;8:589 -592 The results in recent years have been encour­ 20. Heinz RE, Schwartz FJ, Sears RA. Thrombus in the vein of Galen malformation. Br J Radiol1968;41 :424-428 aging and are to a large degree attributable to 21. Mancuso P, Chiaramonte I, Pero G, Tropea R, Guarnera F. A case the advances in endovascular approaches. With of thrombosed aneurysm of the vein of Galen associated with future improved tools for diagnosis and treat­ superior sagittal sinus thrombosis. J Neurosurg Sci 1989;33:305- 309 ment, perhaps the prognosis for this difficult 22. Six EG, Cowley AR , Kelly DL Jr, Laster DW. Thrombosed aneu­ malady also will continue to improve. rysm of the vein of Galen. Neurosurgery 1980;7:274-278 23. Weir BK, Allen PB, Miller JD. Excision of thrombosed vein of Galen aneurysm in an infant. Case report. J Neurosurg 1968;29: References 619-622 24. Whitaker JB, Latack JT, Venes JL. Spontaneous thrombosis of a 1. Long DM, Seljeskoge El, Chous SN, French LA. Giant arterio­ vein of Galen aneurysm. AJNR Am J Neuroradio11987;8:1134- venous malformations and childhood. J Neurosurg 1974;40:304 1136 2. Jaegar JR, Forbes RP, Dandy WE. Bilateral congenital cerebral 25. Lazar ML. Vein of Galen aneurysm: successful excision of a com­ arteriovenous communication aneurysm. Trans Am Neural Assoc pletely thrombosed aneurysm in an infant. Surg Neural 1974;2: 1937;63: 173-1 76 22-24 3. Padget DH. Cranial venous system in man in reference to devel­ 26. Jarrell HR, Schochet SS Jr, Krous H, Barnes P. Turner's syndrome opment, adult configuration and relation to arteries. Am J Anal and vein of Galen aneurysm: a previously unreported association. 1956;98:307- 355 Acta Neuropatho11981;55:189-191 1496 HOROWITZ AJNR: 15, September 1994

27. Rosenblum WI, Nakoneczna I, Konderding HS, Nochlin D, Ghatak 42. Yasargil MG , Anti! J , Laciera R, Jain KK, Boone SC. Arteriovenous NR. Multiple vascular malformation in the "blue rubber bleb nae­ malformations of vein of Galen: microsurgical treatment. Surg vus" syndrome: a case with aneurysm of vein of Galen and vas­ Neural 1970;6: 195-200 cular lesions suggesting a link to the Weber-Osler-Rendu syn­ 43. Barrow DL. Intracranial vascular m alformations. In: Barrow DL, drome. Histopathology 1978;2:301-311 ed. Neurosurgical Topics. AANS 1990:91 28. Eide J, Foiling M. Malformation of the great vein of Galen with 44. Spezler RF, Wilson CB, Weinstein P, Mehdorn J , Townsend J, neonatal heart failure: report of two cases. Acta Paediatr Scand Telles D. Normal perfusion pressure breakthrough theory. Clin 1978;67:529-532 Neurosurg 1978;25:651-672 29. Jea nty P, Kepple D, Roussis P, Shah D. In utero detection of 45. Barrow DL. Intracranial Vascular Malformations. In : Barrow DL, cardiac failure from an aneurysm of the vein of Galen. Am J ed . Neurosurgical Topics. AANS 1990:160 Obstet Gyneco/1990;163:50-51 46. Schneider SJ, Wisoff JS, Epstein FJ. Complications of ventricu­ 30. Mendelsohn DB, Hertzanu Y, Butterworth A. In utero diagnosis of loperitoneal shunt procedures or hydrocephalus associated with a vein of Galen aneurysm by ultrasound. Neuroradiology 1984; vein of Galen malformations in childhood. Neurosurgery 1992;30: 26:417-418 706-708 31. Rodemyer CR, Smith WL. Diagnosis of a vein of Galen aneurysm 47. Berenstein A, Epstein F. Vein of Galen malformations: combined by ultrasound. JCU 1982; 10:297-298 neurosurgical and neuroradiologic intervention. In : American As­ 32. Deeg KH, Scarf J. Colour Doppler imaging of arteriovenous mal­ sociation of Neurological Surgeons, eds. Pediatric Neurosurgery, formation of the vein of Galen in a newborn. Neuroradiology Surgery of the Developing Nervous System. New York: Grune & 1990;32:60-63 Stratton, 1982:638-647 33. Tessler FN, Dion J , Vinuela F, et al. Cranial arteriovenous mal­ 48. Hawkins J , Quisling RG , Mickle JP, Hawkins IF. Retrievable Gi­ formations in neonates: color Doppler imaging with angiographic anturco-coil introducer. Radiology 1986; 158:262-264 correlation. AJR Am J Roentgenol 1989; 153:1 027-1039 49. King WA, Wackym PA, Jinuela F, Peacock WJ. Management of 34. Swischuk LE, Crowe JE, Mewborns EJ Jr. Large vein of Galen vein of Galen aneurysms: combined surgical and endovascular aneurysms in the neonate: a constellation of diagnostic chest and approach. Childs Neru Syst 1989;5:208-211 neck radiologic findings. Pediatr Radio/1977;6:4-9 50. McCord FB, Shields MD, McNeil A, Halliday HL, McClure G, Reid 35. Agee OF, Musella R, Tweed CG. Aneurysm of the great vein of MM. Cerebral arteriovenous malformation in a neonate: treatment Galen. Report of two cases. J Neurosurg 1969;31 :346-351 by embolization. Arch Dis Child 1987;62:1273-1275 36. Martelli A , Scotti G, Harwood-Nash DC, Fitz CR, Chuang SH. 51. Mickle JP, Quisling RG. The transtorcular embolization of vein of Aneurysms of the vein of Galen in children: CT and angiographic Galen aneurysms. J Neurosurg 1986;64:731-735 correlations. Neuroradiology 1980;20: 123-133 52. Dowd CF, Halbach W, Barnwell SL, Higashida RT, Edwards MSB, 37. Seidenwurm D, Berenstein A, Hyman A , Howalski H. Vein of Hieshema EM. Transfemoral venous embolization of vein of Galen Galen malformation: correlation of clinical presentation, arteriog­ malformations. AJNR Am J Neuroradiol 1990; 11 :643-648 raphy and MR imaging. AJNR Am J Neuroradiol 1991; 12:347- 53. Kasabach HH , Merritt KK. Capillary hemangioma with extensive 354 purpura: report of a case. Am J Dis Ch ild 1940;59: 1063-1080 38. Leff SL, Kronfeld G, Leonidas JC. Aneurysm of the vein of Galen: 54. Casasco A, Lylyk P, Hodes JE, Kohan G, Aymard A, Merland JJ. ultrasound, MRI and angiographic correlations. Pediatr Radio/ Percutaneous transvenous catheterization and embolization of 1989;20:98-100 vein of Galen aneurysms. Neurosurgery 1991 ;28:260-265 39. Roosen N, Schirmer M, LinsE, Bock WJ, Stork W, Gahlen D. MRI 55. Mickle AP. The transtorcular embolization of vein of Galen aneu­ of an aneurysm of the vein of Galen. AJNR Am J Neuroradiol rysms and update on the use of this technique in twenty-four 1986;7:733-735 patients. In: Marlin AE, ed. Concepts in Pediatric Neurosurgery. 40. Lasjaunias P, Rodesch G, Terbrugge K, et al. Vein of Galen aneu­ Basel: Karger, 1991;11:69-78 rysmal malformations: report of 36 cases managed between 1982 56. Lylyk P, Vinuela F, Dion JE, et al. Therapeutic alternatives for vein and 1988. Acta Neurochir 1989;99:26-37 of Galen vascular malformations. J Neurosurg 1993;78:438-445 41. Johnston IH, Whittle IR, Besser M , Morgan MK. Vein of Galen malformation: diagnosis and management. Neurosurgery 1987; 20:747-758