Developmental Venous Anomaly

Developmental venous anomaly is the commonest cerebral vascular variant, found in about 2 to 9% of brains. It is a cluster of dilated medullary veins converging on a single draining vein ("caput medusae") and is considered normal venous drainage rather than a malformation.

Pathophysiology. The anomaly is the only drainage of the territory around it. For this reason removal or occlusion risks venous infarction. About 20% are associated with a cavernous malformation, which causes most bleeding.

Most are found incidentally. Symptoms are usually from an associated cavernous malformation, thrombosis of the draining vein or a posterior fossa location, and include seizures, headache, focal deficit and haemorrhage. Rarely, venous congestion causes oedema or infarction.

Contrast enhanced MRI shows the caput medusae pattern and the collecting vein. Susceptibility weighted imaging detects an associated cavernous malformation. Angiography is not needed to diagnose.

Differential diagnosis.

• Arteriovenous malformation and dural fistula.
• Vascular tumour and cavernous malformation alone.

Incidental and uncomplicated. No treatment and no imaging follow up are needed. Reassure the patient. No restriction of activity, pregnancy or anticoagulation is needed because of the anomaly alone.

With a cavernous malformation. Manage the cavernous malformation, with surgery only if it is accessible and symptomatic, taking great care to preserve the draining vein.

Seizures. Levetiracetam 500 mg twice daily, increased to 1500 mg twice daily (adjust to eGFR), for an epileptogenic lesion.

Venous thrombosis or infarct. Anticoagulation for thrombosis of the draining vein: enoxaparin 1 mg/kg SC twice daily, then oral anticoagulant for 3 to 6 months (check renal function).

Avoid resection or embolisation of the developmental venous anomaly itself.

Referral and escalation. Refer to neurosurgery only for associated lesions or symptoms.