Intracranial Dural Arteriovenous Fistula

Intracranial dural arteriovenous fistula is an abnormal connection between meningeal arteries and dural venous sinuses or cortical veins, usually acquired, in adults aged 40 to 70 years. Risk is set by the venous drainage pattern.

Pathophysiology. Sinus thrombosis, trauma, surgery and venous hypertension promote fistula formation. Retrograde cortical venous drainage raises the risk of haemorrhage and venous infarction.

Benign lesions (cavernous and transverse sinus) cause pulsatile tinnitus, orbital bruit, chemosis, proptosis, diplopia and raised ocular pressure. Aggressive lesions with cortical venous reflux cause intracranial haemorrhage, seizures, focal deficit, venous infarction, dementia or raised intracranial pressure.

Red flags.

• Sudden headache or focal deficit.
• Progressive cognitive decline or papilloedema.
• Visual loss with a red eye.

MRI and MR venography may show flow voids, venous congestion and sinus thrombosis. CT angiography screens. Catheter digital subtraction angiography is definitive and defines feeders, sinus patency and cortical venous reflux, which determines risk.

Differential diagnosis.

• Carotid cavernous fistula, cerebral venous thrombosis.
• Idiopathic intracranial hypertension, arteriovenous malformation.
• Thyroid eye disease and conjunctivitis.

Without cortical venous reflux. Observation, with manual carotid compression for cavernous lesions in selected cases. Treat symptoms (tinnitus, ocular pressure with topical agents).

With cortical venous reflux or neurological symptoms. Treat promptly.

• Transarterial or transvenous embolisation (liquid embolic agent or coils).
• Microsurgical disconnection of the draining vein.
• Stereotactic radiosurgery, alone or after partial embolisation, with delayed effect over 1 to 3 years.

Seizures. Levetiracetam 500 mg twice daily, increased to 1500 mg twice daily (adjust to eGFR).

Anticoagulation. Review the need carefully when thrombosis coexists.

Monitoring. Angiography 6 to 12 months after treatment, and review for recurrence.

Referral and escalation. Refer urgently to neurovascular centres when cortical venous drainage is present.