DURAL ARTERIOVENOUS MALFORMATIONS Issam A. Awad, MD, MSc, FACS, MA(hon) Professor of Neurosurgery Evanston Northwestern Healthcare Feinberg School of Medicine Northwestern University Evanston, Illinois

Lesion Definition Plexiform arteriovenous fistulae with the nidus of AV shunting totally within the dural leaflet Fed by pachymeningeal arteries or dural branches of brain or scalp arteries Drained by adjacent dural sinuses, or retrograde through leptomeningeal veins

DAVM Pathoanatomy and Pathophysiology Venous hypertension in dural leaflet Dural sinus outflow restriction/occlusion Retrograde (leptomeningeal) venous drainage Secondary sequelae of parenchymal venous hypertension

DAVM Pathoetiology Sinus occlusion (congenital or acquired) Trauma (blunt, penetrating, surgical) Hypercoagulable states (including neoplasia, inflammation, etc…) Angiogenesis

DAVM Lesion Progression Dural leaflet AV shunting Pachymeningeal arterial recruitment Retrograde venous drainage, variceal/aneurysmal change

DAVM Natural History Clinical presentation related to lesion location Aggressive symptoms (hemorrhage, focal neurologic deficits, seizures, etc.) solely related to leptomeningeal venous drainage Progression, spontaneous resolution highly unpredictable (cavernous sinus DAVMs notable for spontaneous resolution)

Galenic DAVM Spontaneous Resolution At BirthAt 1 Year

DAVM Symptoms: Lesion Location and Pattern of Drainage Flow symptoms, cranial neuropathy Ocular or intracranial hypertension Focal neurologic symptoms, myelopathy, seizures * Hemorrhage * * Aggressive Symptoms

DAVM Features Associated with Aggressive Neurologic Course RETROGRADE LEPTOMENINGEAL VENOUS DRAINAGE Pial drainage, Galenic drainage, Venous varices Awad et al. 1989

DAVM Location and Aggressive Clinical Course Awad et al. 1990

DAVM Classification: Location and Venous Drainage

DAVM Management Strategies Expectant and symptomatic treatment-- surveillance for progression, aggressive features Transarterial embolization-- palliative, preparatory, definitive (slow polymerization) Transvenous embolization-- pathologic segment Surgery-- disconnection of leptomeningeal venous drainage, coagulation/excision/isolation of pathologic dural leaflet/sinus segment Stereotactic Radiosurgery months delayed effect (interval risk)

DAVM Surgical Adjuncts Stereotactic navigation (CTA Guidance) Skull base exposures Intraoperative angiography Intraoperative embolization Evoked potential monitoring

Cavernous sinus DAVMs Painful ophthalmoplegia, red eye, bruit, visual loss Spontaneous resolution, progression of eye symptoms, development of cortical (Sylvian) venous drainage Tx-- transvenous obliteration (endovascular, open), transarterial preparation, radiosurgery, open surgery for leptomeningeal venous drainage or access to cavernous sinus

Cavernous Sinus DAVM: Surgical Access for Transvenous Obliteration

Superior Sagittal Sinus, Torcular DAVM Venous outflow obstruction, papilledema Cortical venous drainage, focal symptoms, hemorrhage Tx.-- transarterial embolization, surgical disconnection, radiosurgery, palliative tx. of papilledema CSF diversion & radiosurgery Surgical disconnection

Superior Sagittal Sinus DAVM: Preparatory Transarterial Embolization and Surgical Disconnection Transarterial embolizationSurgical disconnection

Anterior Falx (Ethmoidal) DAVM Silent clinically until aggressive neurologic symptoms Difficult, risky to embolize Relatively easy to treat surgically Radiosurgery option

Tentorial Incisural DAVM Silent clinically or neighborhood symptoms (tic, bruit, etc.) High frequency of aggressive neurologic symptoms (Galenic drainage) Difficult to cure with embolization alone Open surgery effective, subtemporal or pre-sigmoid transpetrous approach Radiosurgery option

Transverse-Sigmoid (Lateral Tentorial) DAVM Often presents with bruit as only initial symptom Natural course dependant on leptomeningeal venous drainage Treatment options individualized

CTA Guided Stereotactic Disconnection of Transverse Sinus DAVM

Transverse-Sigmoid DAVM: Palliative Embolization and Radiosurgery

Transverse-Sigmoid (Petrosal) DAVM: Unusual “Cure” with Transarterial Embolization Alone Glue embolization with slow polymerization

Transverse-Sigmoid (Petrosal) DAVM: Recanalization after Transvenous embolization Recurrence at edge of coil Recurrence in wall of occluded sinus Surgical excision & disconnection of coiled sinus segment

Clival, Foramen Magnum DAVM Frequent caudal leptomeningeal venous drainage Brainstem symptoms or myelopathy (masquerade as spinal DAVM) Tx.-- embolization, surgical disconnection (transcondylar, presigmoid approaches)

DAVMs: A Strategic Approach Understand lesion pathoanatomy Screen and watch for aggressive features Consider all management options, modalities, limitations, risks Individualize treatment