NEW YORK (Reuters Health) – The risks involved in the endovascular treatment of unruptured intracranial aneurysms are about the same whether the aneurysms is bigger than 3 mm or smaller, but the procedure fails more often in the very small aneurysms, a French group reports in the December issue of Stroke.

The authors therefore advise that very small aneurysms are probably best managed by anatomic monitoring, since their risk of rupture is low but treatment is quite risky.

Dr. Laurent Pierot, with Hopital Maison-Blanche in Reims, and colleagues compared procedural complications and clinical outcomes of endovascular treatment of 682 unruptured intracranial aneurysms in 626 patients; 51 aneurysms were no larger than 3 mm, the other 631 were larger than 3 mm.

Endovascular treatment could not be completed in 13.7% of the smaller aneurysms compared with 3.3% of the larger group (p=0.003), according to the report.

Apart from the treatment failure rate, results were statistically similar in the very small aneurysms and the larger ones. Respectively, rates of intraoperative rupture were 3.9% vs 2.4%; thromboembolic event rates were 3.9% vs 7.1%; and 1-month rates of morbidity or mortality were 2.0% vs 3.3%.