Flow rate may dictate brain arteriovenous malformation radiosurgery success

By Eleanor McDermid, Senior medwireNews Reporter

The presence of angioarchitectural features indicating high flow rate in a brain arteriovenous malformation (AVM) warns that complete obliteration may be difficult to achieve with radiosurgery, say researchers.

In the retrospective study of 139 patients, high flow, arterial enlargement, and perinidal angiogenesis were all associated with a reduced likelihood for complete obliteration.

"We identified three independent angiographical indicators for incomplete obliteration following radiosurgery that can easily be identified on routine angiography," say Timo Krings (Toronto Western Hospital, Ontario, Canada) and co-workers.

However, they caution that "defining details of angioarchitecture may be challenging and are subject to experience of the reader."

By 3 years after radiosurgery, 66% of the patients had achieved complete AVM obliteration. There was a 3.47-fold increase in the likelihood for complete AVM obliteration if they had a low-flow pattern (venous drainage seen in two or more frames after nidal visualization on digital subtraction angiography).

The odds for complete obliteration were increased to a similar extent in the absence of the two indirect indicators of high flow: 3.32-fold without arterial enlargement and 2.61-fold without perinidal angiogenesis.

The obliteration rate was 80% for patients with none or one of these factors, compared with just 38% for those with two or three, Krings et al report in Neurosurgery.

The likelihood for complete obliteration fell with increasing AVM size and was increased more than threefold if the AVM was in a noneloquent location (radiation dose was reduced for eloquent locations).

But the impact of these factors was considerably less than that of the combined angioarchitectural factors. Patients with no or one factor indicating high flow had a 6.62-fold increased likelihood for achieving complete AVM obliteration relative to those with two or three factors.

"This may indicate that angioarchitectural factors may be an equally important indicator to determine the chance of occlusion of an AVM, which could alter the therapeutic approach to brain AVMs and lead to targeted pre-radiosurgical embolization of high-flow components of brain AVMs," conclude the researchers.

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