Galenic Pial Arteriovenous Fistulas in Adults

Highlights

• Galenic pial arteriovenous fistulae (GPAVFs) present insidiously in adult.

• Asymptomatic GPAVFs may be serially observed.

• GPAVFs causing symptoms may be obliterated endovascularly.

• Hemorrhagically ruptured GPAVFs may be subjected to operative intervention.

• Further studies are necessary in order to prospectively evaluate lesion natural history.

Abstract

Background

Vein of Galen aneurysmal malformations (VOGMs) are pial arteriovenous fistulas possessing Galenic venous drainage most commonly presenting during the neonatal period and infancy, with initial discovery during adulthood quite rare.

Objectives and methods

We conducted a literature survey of the PubMed database in order to identify Galenic pial arteriovenous fistulas (GPAVFs) with major manifestation or initial presentation during adulthood. Inclusionary criteria included pial AVFs with Galenic drainage with major manifestation or initial presentation at, or older than, 18 years. Exclusionary criteria included exclusive pediatric onset of symptomatology attributable to GPAVFs without a new onset major presentation during adulthood, exclusive or major dural arterial supply, arteriovenous malformations with Galenic drainage, developmental venous anomalies with Galenic drainage, isolated varices or anomalies of the vein of Galen, and any lesions with uncertainty regarding true GPAVF nature.

Results

Our search generated 1589 articles. Excluding duplicates, 26 cases met criteria for evaluation. Mean age was 34.1 +/− 2.53 years. Clinical presentations of GPAVFs among adults included headache, intracranial hemorrhage, seizures, and focal neurologic deficits. Management strategies included observation (n = 5), emergent ventriculostomy or Torkildsen shunt (n = 3), cerebrospinal fluid diversion via ventriculoperitoneal shunting (n = 4), microsurgical obliteration or thrombectomy (n = 4), transarterial and/or transvenous embolotherapeutic obliteration (n = 7), and concurrent embolotherapy and radiosurgical irradiation (n = 1).

Conclusions

GPAVFs in adults often present with symptomatology of mild severity and may be effectively managed conservatively, though occasionally present catastrophically or may be treated via cerebrospinal fluid diversion, microsurgical obliteration, or endovascular embolization. Severity sufficient to require emergent intervention portended a poor outcome.

Introduction

Vein of Galen malformations (VOGMs) constitute complex high-flow vascular lesions [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75]], inaugurally described by Jaeger, Forbes, and Dandy in 1937. Authors have employed the term VOGM to refer to a variety of somewhat related vascular anomalies intimately involving the vein of Galen (VoG). Pial arterial supply and venous drainage into the vein of Galen without interposed dysplastic nidal vessels constitute true vein of Galen malformations [22,66], arising congenitally in the setting of arterial feeders fistulizing with the VoG or with a median prosencephalic vein of Markowski developmentally-arrested during embryogenesis. The VOGM may alternately drain into either or both the posterior third of the superior sagittal sinus via a persistent falcine sinus or directly to the torcular herophili via a normally-formed straight sinus, coursing within the dural leaflets constituting the triangloidally-shaped falcotentorial junction [22] (Fig. 1, Fig. 2, Fig. 3). High blood flow under arterial pressure conveyed by arterial feeders supplying the lesions generates cystic dilation of venous egress routes (Fig. 4), compressing the mesencephalic tectum and effecting aqueductal stenosis, hydrostatic hydrocephalus, and increased ventricular preload with ensuant high output heart failure in neonates and infants (Fig. 5, Fig. 6).

Authors have developed several schemes in order to adequately classify and characterize these lesions [2,11,49,71,75]. One classification designates true Galenic pial AVFs (GPAVFs) to be alternately choroidal or mural. Choroidal GPAVFs possess a network of fine non-dysplastic (distinguishing these lesions from arteriovenous malformations) choroidal vessels interposed between the arterial feeders and venous drainage (Fig. 1), while mural Galenic pial arteriovenous fistulae, lacking this network, involve direct fistulization of the arterial supply through fewer fistulae with the venous outflow [22,36]. Choroidal VOGMs are situated chiefly within the quadrigeminal cistern and may splay the tela choroidea of the velum interpositum, the bulk of which may be found superomedially with respect to mural type vein of Galen malformations [54]. Yaşargil type IV VoG malformations constitute true arteriovenous malformations (AVMs) transmurally conveying venous drainage into the cavity of the vein of Galen [27,71]. A novel classification scheme predicated upon clinical presentation, arterial supply, and venous egress may risk stratify and prognosticate outcomes with microsurgical intervention and endovascular embolotherapy.

Dural arterial supply, acquired consequent to successive venous sinus thrombosis and luminal recanalization [7,27] occurring during embryogenesis or extrauterine life (e.g., induced by a trauma insult to the cranium) distinguishes dural arteriovenous fistulae possessing Galenic venous drainage [7] from true pial Galenic arteriovenous fistulae [22]. Galenic pial arteriovenous fistulae most commonly present with macrocephalic hydrostatic hydrocephalus or high output biventricular myocardial insufficiency (i.e., high output heart failure) during the neonatal month or the infantile year [22]. Vein of Galen malformations manifesting initially during adulthood may present insidiously or suddenly or be incidentally during imaging conducted to evaluate suspected cranial pathology. GPAVFs may cause intracranial hypertension by compressing the cerebral aqueduct of Sylvius or shunting columns of arterial blood under high pressure into the capacious naturally low-pressure VoG [1,[3], [4], [5],10,13,19,20,26,29,30,34,44,46,48,50,53,56,60,61,63,[67], [68], [69], [70]]. Thus, we sought to survey and evaluate the literature in order to present a cohesive synthesis of the natural history, useful therapeutic paradigms, complications of treatment, and neurological outcomes of Galenic pial arteriovenous fistulae in adults in order to provide a coherent set of qualitative metrics upon which to predicate rational clinical decision making in these patients.