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• 63 yo • SHA • VII cn paresis , • Orbital pain • Dizziness

Natural history and Salvatore Mangiafico Interventional Nurovascular unit classification of dAVF Careggi University Hospital Florence 12

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second case: SHA

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Third Case: seizure

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a problem is always made of several questions and its solution is always to anwser to each one of them

• Is it a A‐V malformation ?

• May this A‐V shunt explain the clincal presentation? the problem is how to treat it ? • Wich is its possible evolution ?

• Where the A‐V shunt is it • Wich way to follow to occlude it ?

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Dural Arterior Venous Fistulas (DAVF) are acquaided vascular «malformations» DAVF account for approximately 10–15% of all intracranial with un unknown aetiology or secondary vascular malformations due to trhombophilic state, phlogistitic or traumatic process in wich multiple 0.16 per 100 000 per year approximately 12.5%of all arteriovenous shunts develop inside dural intracranial AVMs vascular stuctures without the interposition of a malformative nidus. the mean age of presentation is between 50 and 60 years. DAVF are almost exclusively supplied by meningeal arising from esternal , in Japan 0,29 a 100.000 su 1815 casi Acta Neuroch Suppl 2016 internal carotid and vertebral arteries and rarely from intracranial pial branches

Venous drainage can be formed between dural sinus, cortical or both

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Etiopathogenesis : Neo vascularization and venous 3 theories Menigeal arteries have no connection dilatation are induced by an with the sinus and cortical veins (BV) inflammatory process

1)venous sinus occlusion precedes and is 2)DAVFs arise from naturally occurring dormant directly responsible for development of the channels between dural arteries and sinuses, which fistula. Venous sinus thrombosis results in the open when the sinus is occluded and venous pressure is release of angiogenic factors from increased(Pitonet al., 1984; Mullan, 1994). theorganizing thrombus, which subsequently leads to the invasion of small dural arteries and formation of small dural arterio venous 3) Venous hypertension may lead to tissue hypoxia shunts(Houseretal.,1979). and increased production of angiogenic factors, which promote endothelial proliferation and neoangiogenesis (Lawton et al., 1997; Tirakotai et al., 2004; Kojima et al., 2007).

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sinus‐type DAV Fistulas no‐sinus type DAV Fistulas the inflammatory processes and the inflammatory processes throbososis effect a long segment of a and throbosis effect the dural dural sinus It starts from the wall segment of a bridging inside the sinus

Opening of Dural AV Thrombosis of the EV shunt and increases the AV flow Sinus occlusion and penetration of dural Inside the Sinus and EV, reflux in BV arteries inside the Recruitment of other Recruitment of trans sinus Dural feeders osseus feeders

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Hystology

• Histologic studies suggests that microscopic thrombosis is always present and plays an important role in the release of growth factors and theformation o fDAVFs (Uranishi et al., 1999). Site od origin of the DAVF • In immuno‐histochemical studies, expression of basic fibroblast growth factor and vascular endothelial growth factor has been identified in the wall of the dural sinuses in patients withD AVFs (Teradaetal., 1996; Uranishi et al., 1999).

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• The exact site of the original lesion ( EV , DS , BV) may dictate the arterial CDAVF feeders of the lesions, their venous drainage pattern, and as a consequence, their tendency for a certain clinical behavior. • CDAVFs may develop in three distinct levels of the cranial venous system 3 • the bridging veins, BV ,(1) • the dural sinuses, DS ( 2) , • and the , EV (3 ). 2

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dural entrances of the BVs are 1) DAVF of the EV overlapped by a layer of ( osteodural sinus type DAVF) numerous small meningeal Emissary veins pass with cranial nerves through apertures in the cranial wall and veins and venous lacunae establish communication between the sinuses inside the skull and the veins external to it (arrowhead) • mastoid emissary vein • veins in the hypoglossal canal • The parietal emissary • • The • emissary veins of the middle fossa • posterior condylar vein through the foramen ovale, rotundum, lacerum, • temporal emissary • has also the • superficial petrosal vein position and function of an emissary • meningo‐orbital vein vein connecting the cavernous sinus with the

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2 ) DAVF of the SINUS wlall CDAVFs of an Emissary Vein (EV) pure sinus type DAVF

• drain mostly to the sinus and not directly the cortical venous Periostal – dural sinus DAVF system Dural –dural sinus DAVF Sinus at the convexity • • Falcine sinus recruits additionally osseous • arterial feeders • Sinis rectus Base and posterior fossa sinus • adds“purely meningeal” • Tentorial sinus • Transverse sinus branches as the middle • meningeal , posterior • meningeal, or meningeal • branches of the ICA. Torcular

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3) DAVF of the BV( non‐sinus DAVF) (veno‐sinusal Junction)

• The distal segment of a BV embryologically, anatomically, and histologically seems to be part of the dural system. • The BVs are closely attached to the inner dural surface and have a shorter or longer intradural course before they enter the sinus [75]. Therefore,from the embryological point of view, the distal BV segment, veno‐sinusal junction, appears to belong to the dural system.

Tentorial sinus DAVF

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Hui Han Neurosurgery 67; 2010 BV DAV shunt ( two subtypes) Comunicating vein

• arteriovenous dural shunt can be primarily located on a , the veno‐sinus junction is patent ; the A‐V fow is directed towards the sinus and mainly toward the pial vein

• thrombosis of the venous –sinus Junction, the shunt venous drainage is exclusively cortical.

a BV (arrow) from the occipital lobe (O) drains the BVs (arrows) directly entering the dural Disconneted bridging into the meningeal vein (arrowhead) in the sinuses (asterisks) in the middle cranial fossa. vein cerebral falx (F) before entering the SSS Arrowheads indicate the dural entrance sites (asterisk). vein)

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Comunicanting BV

Is the Sinus filling is syncronous with the BV’s

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Disconnected Bridging vein

The Dural AV sunt is on the BV at the conjunction point with Sinus and it does not communicate with the sinus unique drainage trhotugh a pial vein that runs along the falx cerebri Sinus opacifization is delayed

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The natural history of cranial dural arteriovenous malformations (AVM's) is highly variable

Natural history • In adults the natural history of DAVFs is influenced by 1. the pattern of venous drainage 2. the presenting symptoms 3. localization

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The natural history of cranial dural arteriovenous malformations (AVM's) is highly variable

• In adults the natural history of DAVFs is influenced by 1. the pattern of venous drainage DAVFs without CVD 2. the presenting symptoms Sinus type DAVF 3. localization

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DAVF without CVD DAVF with CVD ( cerebral vein drainage)

• a benign clinic course was observed in 98.5% of the patients • annual rate of conversion to a higher • Syntomatology : bruit grade DAVF of 1%‐1.5% angiographic progression to a more aggressive fistula • Managed conservatively • if treatment is contemplated it should not be too aggressive • Follow up of DAVF without VCD (Borden type I) fistulas is generally recommended Bridging vein type DAVF sinus type DAVF with CVD

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• DAVFs that acquire cortical venin dreinage (CVD) can present with aggressive clinical features, including either ICH or nonhemorrhagic neurologic deficits (NHNDs) • The annual ICH, NHND, and related to focal or regional venous hypertension mortality rate was 7.6%, 11%, and • Or progressive clinical features 3.8% (Strom and colleagues (2009 in a dementia,seizures,parkinsonism,or ataxia due series of 28 patients with DAVFs with CVD) to cerebral edema or ischemia related to diffuse and extensive venous hypertension • annual ICH rate o f 8.1%,NHND rate (Barrow et al., 1985; Lasjaunias et al., 1986;Awad etal.,1990). of 6.9%, and a combined annual event rate of 15% • DAVFs draining into perimedullary spinal veins may cause myelopathy and progressive (Toronto Brain Vascular Malformation tetraplegia Group : 20 DAVFs with CVD that were followed over a 4‐year period ) (Hurst et al., 1999; Lv et al., 2011).

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The natural history of cranial dural arteriovenous physiopathology malformations (AVM's) is highly variable

Parenchimal Hem Parenchimal ischemia • In adults the natural history of DAVFs is influenced by ICH is believed to occur from rupture parenchymal ischemia is thought to occur from venous congestion and hypertension, of fragile parenchymal veins as a result 1. the pattern of venous drainage of exposure to increased pressure from Crhronic venous congestion prevents 2. the presenting symptoms retrograde venous reflux.. adequate arterial delivery of oxygen and removal of metabolic byproducts within the 3. localization surrounding parenchyma

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Difference in natural Hystory according to the clinical presentation

• asymptmaic patients : Clinical features of CDVF presenting annual ICH, NHND, and mortality rate was 1.4%, 0%, and 0% with hemorrhage • symptomatic patients : • The vast majority of patients the annual ICH, NHND, and mortality rate was 7.6%, 11%, and 3.8% were male (86%), and the most respectively in common presenting symptom was sudden onset headache. • All DAVFs had cortical venous drainage, and about one‐third (Strom and colleagues ;2009) were associated with a venous varix. The most common location was tentorial (75%).

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1 ) Cotical Dementia from venous congestive encephalopathy DAVF

• Clinically Progressive • intracranial venous pressure with signs • Combination of hig flow fistulas of pseudotumor cerebri with severe with sinus stenosis or thrombosis headaches and papilledema and • Extensive reflux in cortical and occasionally progressive cognitive deep veins decline leading to dementia • Stasis and engorgement in • Two Types of Vascular Dementia related leptmeningeal and deep venous circulation to DAVFs • Trans medullary vein congestion withe matter edema and hydrocepahalus

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of CT or MR imaging revealed abnormalities in each patient, reflecting the impaired parenchymal venous drainage

pseudophlebitic pattern (PPP) describe Tortuous, engorged veins on the venous phase of the brain circulation

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2) Thalamic Dementia Icv hypertenion Bi‐thalamic edema

6 m decline cognitive Cognard grade IIb dAVF. 51 52

The natural history of cranial dural arteriovenous 14 pts mean FU 4,5 years • annual mortality rate of malformations (AVM's) is highly variable Natural Hystory • an 10.4%. Clinical course ovf (35%). • annual risk for hemorrhage8.1% CDAVF with long term • non hemorrhagic • In adults the natural history of DAVFs is influenced by persistent cortical neurological deficit was • Annual risk of non (45%) hemorrhagic neurological 1. the pattern of venous drainage venous reflux • 6 patients expired after a deficit 6.9%, hemorrhage, and 3 patients • resulting in an annual 2. the presenting symptoms died of progressive event rate of 15.0%. neurological deterioration. 3. localization • Two patients a spontaneous closure of the DAVF (10%).

( J.Marc et al Stroke. 2002;33:1233‐1236.)

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Mode of presentation and location of DAVFs • transverse‐sigmoid sinus DAVF (TS DAVF) are closely related . A) Group 1. TS DAVF without restriction of parent sinus. B) Group 2. TS DAVF with stenosis of parent sinus. • Transverse sigmoid junction DAVFs typically suffer from pulsatile tinnitus due to C) Group 3. TS DAVF with one side the presence of a high‐flow,low‐pressure shunt in close proximity to the auditory occlusion(thrombosis) of parent sinus. apparatus. ICH in case of leptomenigeal reflux D) Group 4. TS DAVF with proximal and distal portion occlusion (thrombosis) of parent sinus. • Middle fossa DAVFs are more likely to present with pulsatile tinnitus due to This group has retrograde leptomeningeal increased drainage through the sigmoid and . venous drainage only and was called as TS DAVF with isolated sinus. E) Group 5. TS DAVF with pure leptomeningeal venous drainage. The parent sinus is patent. Subgroup was the presence of LMVD, the presence of venous aneurysm and the presence of spinal venous drainage.

Lalwani’s classification o

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fistulas (DAVF) drains into leptomeningeal vein (LMV) without the venous sinus interposition

C Est sin pre embol

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Cavernous davf

• Cavernous sinus DAVFs (indirect CCFs) arterialize the and typically present with exophthalmos, chemosis, and visual loss due to increased intraocular pressure (Suh et al., 2005)

Barrow classification

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Clinical symptoms and Imaging

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JVjugular vein, SSsigmoid sinus, 6 cerebellar (spinal) drainage into petrous 1 anterior drainage into (SOV) STVsuperficial temporal vein vein (PV), leading to ataxia and hemorrhage and (IOV), which can lead to ocular symptoms (eg, exophthalmos and chemosis); 2 postero.inferior drainage into inferior petrous sinus (IPS), basilar plexus and , leading to bruit and cranial nerve deficits; 3 posterior drainage into superior petrous sinus (SPS), leading to bruit; 4 cortical reflux into and superficial middle cerebral vein (SMV), leading to venous infarction and hemorrhage; 5 deep drainage into deep middle cerebral vein and uncal vein, leading to hemorrhage. .

RadioGraphics 2004; 24:1637–1653 63 64

DAVF Anterior cranial Fossa

• Anterior cranial fossa DAVFs often present with hemorrhage given the frequency 1. Head hache of retrograde CVD with these fistulas, but they can also present with proptosis 2. seisure and chemosis if they acquire cavernous sinus drainage. 3. Visual defect 4. ICH (61 **‐68%*)

Awad et al (1990) * Agid et al (2009) **

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• The tentorial middle region (TMR) includes the midline and paramedian tentorium TMR DAVFs are divided into the following four types: • Tentorial DAVFs have also been observed to carry a high risk of intracerebral hemorrhage since they almost always acquire retrograde cortical vein drainage • incisural DAVF, • Galenic DAVF, • DAVF • and torcular DAVF

Acta Neurologica Belgica https://doi.org/10.1007/s13760‐018‐1044‐3 67 68

Superior Petrsal vein DAVF : VII cn peripheral paresis Tentorial medial region DAVF

• frequently have retrograde drainage through CVs and deep drainage through the vein of Galen • hemorrhage, • bilateral thalamic venous hypertension • perimedullary medullary syndrome. • The draining vein may become variceal due to the high flow. • Even more rarely, the draining vein can dilate into a giant venous ampulla, causing mass effects ( cranial nerve paresis). • are classified as Borden II‐III and Cognard IIb‐IV

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petrosal vein– draining DAVFs • Petrosal vein DAVF : cranial nerve

• were localized to the dural zone around the termination of the petrosal vein as it penetrates the into the Symptomathology • SAH • venous congestion (supratentorial region in and spinal in • , cerebellar hemorrhage , • trigeminal neuralgia • , and mass effect

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’ Venous dreiange of inferior tentorial and petrosal vein DAVF

Petrosal vein DAVF Vena basale

• 2 type of venous Vena latereo dreinage mesencefalica • • Vena ponto Ascending or ipsilateral ascending course trigeminale • Descending through the lateral mesencephalic vein, basal vein, • According to and the vein of Galen anatomical dispostion of the petrosal vein Varice .Lateral type Mmedial type. The vena di dandy The superior petrosal superior petrosal sinus sinus drains laterally and has no connection has no connection with the transvers e- medially with the sigmoid junction and cavernous sinus drains onl y medially

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56 v o m Venous dreiange of inferior tentorial and petrosal vein DAVF since 2 years facial neuroalgia ( trigeminal nerve V2) From few months oral neuralgia induced by swalallowing ( right glossofaringeal nevralgia )

• to the contralateral side through the transverse pontine vein, the vein of the pontomedullary sulcus, or the anastomotic vein of the lateral recess of the fourth ventricle

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Petrosal vein DAVF (BV davf , extrasinusal DAVF

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Superior Petrsal vein DAVF : VII cn peripheral paresis

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Medulla bridging vein

• Brainstem DAVFs are more likely to present with quadriparesis and lower cranial nerve palsies.

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Medulla Bridging Vein–Draining DAVFs

near the foramen magnum Site of dural shunt • Drainage into the medullary vein • the vein of the pontomedullary sulcus and/or the spinal vein • occiput– C1 space • the lateral medullary vein • ascending venous drainage into the • level of the foramen magnum • Pont med cortical vein of the cerebellum or antero lateral med vein sulc v • above the foramen magnum. supratentorially through the lateral are connected with bridging vein to pontine and lateral mesencephalic vein 1. the sigmoid sinus Antero lat • Descending drainage through the med v dural branches 2. inferior petrosal sinus near the jugular foramen, anterior and/or posterior spinal vein Lat med v VA and/or branches of the 3. to the marginal sinus near the hypoglossal canal. neuromeningeal trunk of the ascending pharyngeal artery

Matsushima T, Rhoton AL Jr, de Oliveira E, Peace D: Microsurgical anatomy of the veins of the posterior fossa. J Neurosurg 59:63–105, 1983 85 86

Extra sinusal type DAVF CCJ DAVF,

• feeding vessels were C1 and C2 radicular artery and draining vessels were posterior medullary vein or anterior medullary vein or intracranial vein. When draining vessels were posterior medullary vein or anterior medullary vein, patients presented with myelopthy. • If CCJ DAVF had venous aneurysm, patients presented with subarachnoid haemorrhage

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Davf 1. Introducing in the comunication a common A) Classification based on Embriology Language classifications 2. better understanding the pathology are useful for 3. foreseing the clincial evolution

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Embryology of Dura

• Embryologically, the intracranial dural membrane is derived from bony structures • It is formed by two connective tissue layers: an external periosteal layer and an inner meningeal layer • the outer dural layer forms the inner periosteum ( perioseal layer) it is highly vascularizes • bony structures consist of two types of bony tissue endochondral bone with cartilaginous ossification and membranous bone based on the intramembranous ossification

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three different dural compartments VE group: Ventral Epidural group related to the embryologic bony structures: on the surface of endochondral • 1. The ventral group of endochondral bone bone from the dura propria and osteal dura (VE group) • carotid cavernous sinus, • 2. The dorsal group of membranous bone • sigmoid sinus from the dura propria and osteal dura (DM group) • Anterior condylar confluence • 3. The falx and tent of the cerebellum group only from the dura propria (FT • Dural arteriovenous shunts in these regions involve group) mainly the epidural space and are in direct contact with the adjacent osseous structures that they may invade or recruit the blood • The venous afferents of these regions are closely related to the bony structures‐ Osteodural DAVF

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Sigmoid sinus DAVF

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Clinic features ventral epidural group • female predominance, more benign clinical presentations, lower rate of cortical and spinal venous reflux, restriction of the venous outflow.

ACC: anterior condilar confluence SPS JF : j ugular foramen ACV SM: sinus marginalis sin OS : occipital sinus SPI SCS: sub occipital cavernous sinus AnteriorLCV: lateral condylar condular DAVF vein ACC ACV dx ACV: anterior condilar vein ACV PCV: posterior condilar vein HCG : Hypoglossal Canal SM 97 98

DM group: Dorsal group

On the surface of membranous bone • The transverse sinus, • confluence (torcular Herophili), • marginal sinus (dorsal portion), • medial occipital sinus • accessory epidural sinuses on the dorsal surface of posterior

Marginal sinus ( dorsal portion ) 99 100

3. FT DAVF dura propria group (two folding internal layers ) Clinic features ventral dorsal group The dorsal epidural group had a lower mean age and a higher rate of multiplicity DURA PROPRIA Moore aggressive presentation • superior sagittal sinus High rate of cotical reflux due to outflow restrictin • falcine sinus and inferior sagittal sinus • Tentorial siunus (Falx and tent of the cerebellum ) • olfactory groove (paramedian surface of crista galli),

DVAFs are located where the pial emissary bridging vein pierces the dura BV DAVF

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SM1

Tentorial sinus DAVF

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• The lateral epidural group presented later in life with a male predominance, more aggressive clinical presentations • include DAVS draining into emissary‐ bridging vein .cortical venous reflux is present without evidence of venous outflow restriction.

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Drainage pattern and clinical difference

• Drainage pattern • cranial VE and DE type of b) Hemodynamic Classification based on the DAVSs was primarily through VE the sinuses, resulting in Types FT angiographic findings I, IIa, IIb, and IIab according to the Cognard classification secondary changes of the DAVF outflow and Type 1 and Type 2 according to the Borden classification depending on outflow restrictions. • FT type (Lateral Epidural LE) DM epiduralspaces ) dreinage was Male/female primarly through the BV resulting in BordenType3 and Cognard 3‐5

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SM1 alongi Salvatore Mangiafico, 9/13/2008 04.11.2019

Secondary Thrombotic phenomena of the venous sinus itself or its connections with BVs and EVs apparently will modify this original tendency of the intact anatomic disposition • Djinjian ‐Merland • Borden • Cognard

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Borden type 3

• shunts with exclusive leptomeningeal venous drainage • fistula engaging a bridging vein that had lost its connection to the parent sinus into which it previously drained; it was characterized by an arterial network of feeders converging onto the wall of a bridging vein, with leptomeningeal venous reflux Borden type 2 shunts with mixed sinusal‐cortical • sinus was opacified prior to the BVs Borden Type I dural AVFMs drain venous directly into Partially or Thrombosed or stenotic Sinus or meningeal veins. leptomeningeal venous reflux following the opacification of the sinus

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annual hemorrhage rate and angioarchitecture Cognard Classification Borden type 2 Borden type3 • female predilection • Male predominance , mean age was 59 Patterns of venous drainage allowed classification of dural AVFs into • 18% percent of type II dAVF presented years. with hemorrhage five types: • , and only 3% were cavernous. • the annual hemorrhage rate was 6% • type I, located in the main sinus, with antegrade flow; • the mean age was 60 years and the male‐ • 34% rate of hemorrhagic presentation to‐female ratio was 0.7, similar to type I • annual rate of hemorrhage 10% • type II, in the main sinus, with reflux into the sinus (IIa), cortical veins dAVF. (IIb), or both (IIa + b) • • A notable majority of dAVF were Borden type III dAVF with venous ectasia, rate transverse‐sigmoid (61%), with the of hemorrhagic presentation was similarat26 • type III, with direct cortical venous drainage without venous ectasia second most frequent location being %,but the annual hemorrhage rate 21% cavernous (10%) • type IV, with direct cortical venous drainage with venous ectasia; • The most common location • type V, with spinal venous drainage. Borden 2 and 3 tentorial(28%),and petrosal (13%). annual rates of 4% for NHNDs. • 9% were transverse‐sigmoid Radiology. 1995 Mar;194(3):671-80 The annual mortality rate as a result of Bradley A. Gross, dAVF NATURAL HISTORY NHNDs was 1% Neurosurgery 71:594–603, 2012 113 114 04.11.2019

B) Classification based on the letomenigeal venous dreinage

In both the Bordenand Cognard classification systems, the higher the fistula grade the worse the natural history (Borden et al., 1995; Cognard et al., 1995).

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Classifications ( Borden and Cognard) focused on the venous drainage, presence of leptomeningeal venous refllux, and on the direction of flow

“none of the above classifications ( Broden Cognard ) • Differntiates direct from exclusive leptomeningeal venous drainage, • considers cortical venous congestion • Consider ectasia in dural sinus‐cortical venous drainage

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Caso seno sospeso “ dural shunts are grouped according to three factors

• Directness (d) of leptomeningeal venous drainage expresses the exact site of the shunt (bridging vein vs sinus wall) • Exclusivity (e) Almost all bridging vein shunts and all “isolated” sinus shunts had an exclusive leptomeningeal • Venous strain (s), manifested as ectasia and/or congestion, denotes the decompensation of the cerebral venous system due to the shunt reflux

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• direct LVD was defined by venous drainage that used the bridging and leptomeningeal vein(s) without interposition of any sinus. In these cases, the exact location of the shunt Dural sinus shunt (DDS) and Brdignig vein shunt(BVS) was the bridging vein (BV) and not the venous sinus. 8 groups • non direct LVD was defined by venous drainage that used the BVs but with the interposition of a sinus, which implies that the shunt was primarily or solely located in green have non exclusive LVD ;therefore ,they drain to both the sinus and the cortical veins; they the wall of the sinus. correspond to Borden type II • exclusive LVD was defined as venous drainage by only the leptomeningeal veins either because the shunt was located in a BV with its exit to the sinus occluded or because the text only exit of the sinus was through the BV s to the leptomeningeal venous system. text in in white black • nonexclusive LVD was defined by drainage that occurred both by cortical veins and also have no have by the venous sinuses, dural veins, or emissary veins (EV). signs of signs leptomen of • Presence of ectasias or congestive pseudophlebitic appearance was recorded as cortical ingeal lepto venous strain. Other associated venous outflow restrictions (VOR) of the venous sinuses, venous meni as complete or partial thrombosis or stenotic appearance, werealso recorded. strain ngeal veno us red have an exclusive LVD ( leptomeningeal venous dreinage) ; strain they correspond to Borden type III

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nD‐nE‐nS nD‐nE‐S dural shunt

DAVF with dreinage towards bridging Vein and Dural sinus DAVF with drainage in varicose bridging and Dural sinus

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nD‐E‐nS nD‐E‐S dural shunt DAVF with non direct , esclusive in cortical , non ectasic vein DAVF with non direct , esclusive in cortical , ectasic vein ( isolated sinus ) ( isolated sinus with venous ectasia )

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D‐nE‐nS D‐nE‐S dural shunt BV Davf with direct towards a non ectatic cortical vein ; dreinage non exclusive (also into the sinus ) Non Esclsive direct cortical vein drainage with veous ectasia Non isolated BV ( comunicates with sinus ) Non isolated BV ( in comunication with the sinus)

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D‐E‐nS dural shunt Esclsive direct cortical vein drainage without veous ectasia Isolated BV D‐E‐S dural shunt Esclsive direct cortical vein drainage with vneous ectasia

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conclusion

Dss dural sinus shunt Intracranial dural fistulas differ in ISS isolated sinus shunt • clinical expression ,and evolution BVS bridging vein shunt • bleeding rate • gender differences • primary localization (sinus non sinus) • embryological development (Dorsal basal ventra lateral Epidural spaces ) • entity of cerebral venous involvement (focal, regional or diffuse) • typology of venous dreinage

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conclusion

Each DAVF has exclusive features

Intracranial dural fistulas are not a homogeneous pathology

The functional anatomical understanding ( beyond the Calssification ) is essential before any therapeutic action

Natural history and Salvatore Mangiafico Interventional Neurovascular unit classification of dAVF Careggi University Hospital Florence 133 134