Developmental venous anomaly coexisting with a true arteriovenous malformation: a rare clinical entity.

Two patients diagnosed with arteriovenous malformation (AVM) in close association with a developmental venous anomaly (DVA) are reported. The first patient presented with episodes of left extremity weakness and numbness as well as chronic headaches. The second patient presented with spontaneous intracerebral hemorrhage. Cerebral angiography showed that both the AVM and the transmedullary veins of the DVA drained through the transcortical vein. The AVMs were treated by highly selective transarterial embolization with Onyx embolic agent while preserving the DVAs. It is suggested that the cause of the presentation in both patients was secondary to the association of the AVM with the delicate hemodynamic balance and less robust angioarchitecture of the DVA.