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Arteriovenous Malformation

Summary

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  • Congenital vascular anomaly characterised by abnormal connections between arteries and veins, bypassing the capillary bed
  • Most commonly occurs in the brain, but can affect any organ system
  • Presents with haemorrhage, seizures, or neurological deficits in cerebral AVMs

Pathophysiology

  • Abnormal development of embryonic vascular system
  • Direct arteriovenous shunting without intervening capillary network
  • Progressive dilation of feeding arteries and draining veins
  • Risk of rupture due to high-flow, high-pressure system

Demographics

  • Prevalence: 18 per 100,000 adults
  • Male to female ratio: 1:1
  • Most common age of presentation: 20-40 years
  • Sporadic occurrence in majority of cases
  • Associated with hereditary haemorrhagic telangiectasia in some cases

Diagnosis

  • Clinical presentation:
    • Intracranial haemorrhage (50%)
    • Seizures (30%)
    • Headaches (15%)
    • Focal neurological deficits (5%)
  • Physical examination:
    • May be normal
    • Focal neurological deficits
    • Bruit on auscultation (rare)
  • Laboratory tests:
    • Generally not specific for AVM diagnosis

Imaging

  • Computed Tomography (CT):
    • Non-contrast CT: Hyperdense serpiginous structures
    • CT Angiography: Delineates feeding arteries and draining veins
  • Magnetic Resonance Imaging (MRI):
    • T1-weighted: Flow voids
    • T2-weighted: Mixed signal intensity
    • Susceptibility-weighted imaging: Haemosiderin deposition from previous haemorrhage
  • Digital Subtraction Angiography (DSA):
    • Gold standard; defines the nidus, feeding arteries, draining veins and flow dynamics
  • Spetzler-Martin grade guides treatment risk, scoring nidus size, eloquence of adjacent brain and deep venous drainage1
  • Report features predicting haemorrhage: associated (nidal/flow-related) aneurysms, deep or exclusively deep venous drainage, and venous stenosis

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  • A 30-year-old patient presented with right sided pulsatile tinnitus.
  • Time-of-flight angiography showed a hypertrophied right PICA and a small AVM nidus near the fourth ventricle.
  • Confirmed with ASL, the lesion was associated with shunting into the left transverse sinus (high signal on ToF MRA and elevated CBF on ASL).

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  • A 40-year-old patient presented with a headache and right sided weakness.
  • CT showed a left temporal haematoma with associated calcification.
  • CTA and DSA showed an arteriovenous malformation supplied by the left MCA with cortical drainage.

Treatment

  • Options are microsurgical resection, endovascular embolisation and stereotactic radiosurgery, alone or combined
  • Choice is guided by Spetzler-Martin grade and rupture status; unruptured low-grade AVMs may be observed (ARUBA)

Differential diagnosis

Differential Diagnosis Differentiating Feature
Cavernous malformation Lack of arterial flow on angiography
Capillary telangiectasia Smaller size and less prominent on imaging
Developmental venous anomaly Characteristic "caput medusae" appearance on contrast-enhanced imaging
Tumour (e.g., glioma) Presence of mass effect and surrounding oedema
Cerebral aneurysm Typically appears as a saccular outpouching on a vessel
Moyamoya disease Bilateral involvement of internal carotid arteries with characteristic "puff of smoke" appearance
Dural arteriovenous fistula Direct connection between dural arteries and venous sinuses
Sturge-Weber syndrome Associated facial port-wine stain and leptomeningeal angiomatosis
Cerebral abscess Ring-enhancing lesion with surrounding oedema and fever
Multiple sclerosis Ovoid periventricular white matter lesions on MRI

  1. Spetzler et al. A proposed grading system for arteriovenous malformations. 1986. Journal of neurosurgery - Open in new tab. ↩