Pure arterial malformation with associated aneurysmal subarachnoid hemorrhage: Two case reports and literature review.

In recent years, in the absence of venous component, dilated, overlapping, and tortuous arteries forming a mass of arterial loops with a coil-like appearance have been defined as pure arterial malformation (PAM). It is extremely rare, and its etiology and treatment have not yet been fully elucidated. Here, we reported 2 cases of PAM with associated aneurysmal subarachnoid hemorrhage in this paper. Both patients had severe headache as the first symptom. Subarachnoid hemorrhage was found by CT and computed tomography angiography (CTA) and PAM with associated aneurysm was found by digital subtraction angiography (DSA). In view of the distribution of blood and the location of aneurysms, the aneurysm rupture was the most likely to be considered. Based on the involvement of the lesion in the distal blood supply, only the aneurysm was clamped during the operation. It used to be consider that PAM is safety, because of the presentation and natural history of previously reported cases. Through the cases we reported, we have doubted about "the benign natural history" and discussed its treatment. PAM can promote the formation of aneurysms and should be reviewed regularly. The surgical indications for PAM patients with aneurysm formation need to be further clarified. Management of PAM patients with ruptured aneurysm is the same as that of ruptured aneurysm. Whether there are indications needed to treat simple arterial malformations remains to be further elucidated with the multicenter, randomized controlled studies on this disease.