DURAL ARTERIOVENOUS MALFORMATIONS

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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

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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

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DAVM Pathoanatomy and Pathophysiology

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

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DAVM Pathoetiology

• Sinus occlusion (congenital or acquired)
• Trauma (blunt, penetrating, surgical)
• Hypercoagulable states (including neoplasia,
  inflammation, etc)

Angiogenesis
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DAVM Lesion Progression

• Dural leaflet AV shunting
• Pachymeningeal arterial recruitment
• Retrograde venous drainage, variceal/aneurysmal
  change

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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)

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Galenic DAVM Spontaneous Resolution
At Birth
At 1 Year
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DAVM Symptoms Lesion Location and Pattern of
Drainage

• Flow symptoms, cranial neuropathy
• Ocular or intracranial hypertension
• Focal neurologic symptoms, myelopathy, seizures
• Hemorrhage
• Aggressive Symptoms

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DAVM Features Associated with Aggressive
Neurologic Course

• RETROGRADE LEPTOMENINGEAL
• VENOUS DRAINAGE
• Pial drainage, Galenic drainage, Venous varices

Awad et al. 1989
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DAVM Location and Aggressive Clinical Course
Awad et al. 1990
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DAVM Classification Location and Venous Drainage
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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-- 18-24 months delayed
  effect (interval risk)

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DAVM Surgical Adjuncts

• Stereotactic navigation
• (CTA Guidance)
• Skull base exposures
• Intraoperative angiography
• Intraoperative embolization
• Evoked potential monitoring

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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

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Cavernous Sinus DAVM Surgical Access for
Transvenous Obliteration
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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
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Superior Sagittal Sinus DAVMPreparatory
Transarterial Embolization and Surgical
Disconnection
Transarterial embolization
Surgical disconnection
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Anterior Falx (Ethmoidal) DAVM

• Silent clinically until aggressive neurologic
  symptoms
• Difficult, risky to embolize
• Relatively easy to treat surgically
• Radiosurgery option

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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

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Transverse-Sigmoid (Lateral Tentorial) DAVM

• Often presents with bruit as only initial symptom
• Natural course dependant on leptomeningeal venous
  drainage
• Treatment options individualized

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CTA Guided Stereotactic Disconnection of
Transverse Sinus DAVM
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Transverse-Sigmoid DAVM Palliative Embolization
and Radiosurgery
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Transverse-Sigmoid (Petrosal) DAVM Unusual
Cure with Transarterial Embolization Alone
Glue embolization with slow polymerization
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Transverse-Sigmoid (Petrosal) DAVM
Recanalization after Transvenous embolization
Surgical excision disconnection of coiled
sinus segment
Recurrence at edge of coil
Recurrence in wall of occluded sinus
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Clival, Foramen Magnum DAVM

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

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DAVMs A Strategic Approach

• Understand lesion pathoanatomy
• Screen and watch for aggressive features
• Consider all management options, modalities,
  limitations, risks
• Individualize treatment