Dural Arteriovenous Fistulas (dAVFs) Βασίλειος Ραπτόπουλος Νευροχειρουργική κλινική ΓΝΑ «Γ.Γεννηματάς»

Definition Abnormal arteriovenous shunts within the dural leaflets Abnormal arteriovenous shunts within the dural leaflets in AVMs: nidus in pia mater, no dural feeders

dAVFs 5-20% of all intracranial malformations Most common acquired intracranial vascular malformation 6 th – 7 th decade Arterial supply from dural arteries (less common: osseous branches) Venous drainage via dural venous sinus, cortical veins or both Symptoms secondary to venous congestion 8% multiple dAVFs

Pathogenesis Sinus thrombosis Venous hypertension ??? Recanalisation Pre-existing dural microvascular channels Enlarged by venous hypertension Neoangiogenesis BFGF, VEGF Dural AVF formation ?Head injury ?Craniotomy ?Hypercoagulability

Clinical Presentation Pulsatile tinnitus, objective bruit Haemorrhage (ICH, SDH, SAH, IVH) NHND (Non-hemorragic neurological deficit) Focal Global Visual disturbances Opthalmoplegia Visual loss Glaucoma Papilledema Facial pain (compression of V1, V2 at the lateral wall of the cavernous sinus)

Diagnosis Golden Standard: 6-vessel angiography Presence or absence of CVR (determination of the exact site) Venous sinus occlusion * Direction of flow in sinuses Venous drainage pattern of brain ?MRI/MRA * Careful in symptomatic patients!! - deficits may improve with restoration of normal flow

Classification Borden ClassificationCognard Classification Type I: Drainage into venous sinus or meningeal vein only Type I: Drainage into dural venous sinus only, antegrade flow Type IIa: Drainage into dural venous sinus only, retrograde flow Type II: Drainage into dural venous sinus or meningeal vein + CVR* Type IIb: Drainage into dural venous sinus (antegrade flow) + CVR Type IIa+b: Drainage into dural venous sinus (retrograde flow) + CVR Type III: CVR onlyType III: CVR only without venous ectasia Type IV: CVR only with venous ectasia Type V: Drainage into spinal perimedullary veins *CVR: Cortical Vein Reflux

Natural History Borden Type Aggressive Presentation % I2% II39% III79% Aggressive presentation defined as ICH, NHND or death as the presenting symptom Davies et al., “The validity of classification for the clinical presentation of intracranial dAVFs”, J Neurosurg 1996

Management Options Observation For dAVFs without CVR ANY change in symptoms might signal development of CVR (2-3%) Serial MRI/MRA + angiogram after 3 years Endovascular Transarterial embolization (palliative or preoperative) Transvenous embolisation Surgical Venous access + direct packing of sinus Surgical excision CVR disconnection

Borden type I Benign natural history: 2% of ICH, NHND (Van Dijk et al, 2002) 2-3% to develop CVR Palliative or no treatment Right occipital artery, antegrade flow into transverse/sigmoid sinus (Cognard I) Left vertebral artery, retrograde flow into transverse/sigmoid sinus (Cognard IIa)

Management Strategy No CVR (Borden I, Cognard I, IIa) Asymptomatic or tolerable symptomsObservation No change in Symptoms Continue Observation Serial MRI + MRA Repeat angiogram in 3 years Worse OR Better Repeat angiogram Intolerable symptoms Palliative treatment (e.g., endovascular transarterial embolization of feeders) Benign Fistulas

Borden type II Type II + III: 15% annual risk of rebleeding 35% rebleed within 2 weeks (one series) Complex management strategy – multidisciplinary approach LECA angiogram, superficial temporal artery, antegrade flow into SSS, with CVR (Cognard IIb) LECA angiogram, occipital artery, retrograde flow into transverse sinus, with CVR (Cognard IIa+b)

Management Strategy CVR and sinosal drainage (Borden II, Cognard IIb, IIa+b) No neurological deficit Assess venous phase of angiogram Sinus not used by brain Complete obliteration or excision of lesion including sinus sacrifice OR CVR disconnection only (endovascular transvenour or surgical) Sinus used by brain CVR disconnection only (endovascular transvenous or surgical) Neurological deficit secondary to venous congestion Interruption of feeding arteries only (transarterial endovascular or surgical) Aggressive Fistulas (with sinus drainage)

Borden type III RECA angiogram, superficial temporal artery, CVR, no ectasia (Cognard III) RECA angiogram, posterior branch of MMA, ectatic cortical vein drainage(Cognard IV)

Management Strategy CVR only (Borden III, Cognard III, IV, V ) No neurological deficit Assess venous phase of angiogram Refluxing cortical vein not used for drainage of brain CVR disconnection (endovascular transvenous or surgical) Refluxing cortical vein used for drainage of brain Interruption of arterial feeders only (endovascular transarterial or surgical) Neurological deficit secondary to venous congestion Interruption of feeding arteries only (endovascular transarterial or surgical Aggressive Fistulas (without sinus drainage)

Transverse/Sigmoid Sinus dAVFs Arterial SupplyECA (occipital, posterior auricular, MMA, ascending pharyngeal) VA (posterior meningeal branch) ICA (meningohypophyseal trunk) Petrous bone Venous drainageIpsilateral or contralateral sinus (if thrombosed) Cortical veins (temporal, occipital, cerebellar) - Most common (40-60%)

Transverse/Sigmoid dAVFs CVR: Dural flap based on sinus Disconnect ALL arterialized veins Complete excision: Drill bone laterally (mastoid & petrous) to expose sigmoid sinus (anterolateral dura) Dura incision above & below TS (medial to lateral) Occlude & cut TS medially Expose and cut tentorium Extend to junction Evaluate venous anatomy (Labbe, sigmoid sinus patency)

Cavernous Sinus fistulas TypeFeeding arteriesSpontaneous Resolution? ADirect fistula between ICA & CS High-flowNo BICA meningeal br. Low-flowYes CECA meningeal br. DICA + ECA meningeal br. Barrow et al classification of carotid-cavernous fistulas …presented next week…

Anterior Cranial Fossa dAVFs Arterial supply: anterior and posterior ethmoidal a. Venous drainage: ALWAYS cortical veins (frontal, olfactory) Aggressive lesions Treatment: Surgery (unilateral frontal or bifrontal craniotomy) !Embolisation  risk of central retinal artery occlusion

Convexity dAVFs Arterial supply: MMA Venous drainage: SSS +/- CVR Treatment: Surgery Other options for high-flow fistula into SSS (without CVR) associated with papilledema: LP shunt Optic nerve sheath decompression

Deep venous dAVFs Arterial supply: ECA, ICA, VA, PCAs (tentorial dural branches) ?Hypertrophic dural arteries (including Bernasconi, Davidoff) Venous drainage: Rosenthal, LMVs, Galen Aggressive lesions If drainage into LMV  quadriparesis Treatment: Surgery (CVR disconnection)

Superior petrosal sinus dAVFs Arterial supply: ECA, ICA, vertebrobasilar (dural branches) Venous drainage: Usually (94%) CVR with SPS thrombosis Presentation: ICH 50% Ocular symptoms (w/ reflux into CS & SOV) Trigeminal neuralgia Treatment: Surgery (subtemporal craniotomy, posterior petrosectomy, suboccipital craniotomy) Aim for CVR disconnection

Inferior petrosal sinus dAVFs Arterial supply: Vertebrtal a., ECA (ascending pharyngeal, MMA, occipital) Venous drainage: Retrograde to IPS  CS Jugular bulb (tinnitus) Retrograde to transverse/sigmoid sinus Treatment: Surgery (far lateral approach) Aim at CVR disconnection

Results Van Dijk et al, Toronto, 2004: 94.1% cure (25% endovascular, 25% surgical, 44% combined) All complications transient (17.56% surgical, 4% endovascular) No deaths or permanent neurological deficits CVR disconnection equal to total excision Ambekar et al, Miami, 2015: 14.3% recurrence following endovascular treatment alone Baltsavias et al, Zurich, 2014: 85% complete occlusion following endovascular treatment alone

Thank you!