Introduction
Moyamoya disease (MMD) is a chronic and progressive cerebrovascular
occlusive disease involving the end of the internal carotid artery (ICA)
and the main branches within the circle of Willis (COW) [1, 2]. In
Korea and Japan, more than half of the adult patients with MMD present
with hemorrhagic stroke [2, 3]. The risk of recurrent hemorrhage in
MMD is estimated at 11%-25% within five years and 19%-36% within ten
years, with each subsequent hemorrhage increasing the risk of poor
neurological outcomes [4]. The incidence of MMD-associated aneurysms
is estimated to be 3%-14%, although the frequency of aneurysmal
rupture as the cause of hemorrhagic MMD remains uncertain [5, 6].
MMD-associated aneurysms can be classified as peripheral aneurysms,
which originate from collateral vessels, or saccular aneurysms, which
originate from major intracranial arteries [7].
The treatment strategies for MMD-associated peripheral aneurysms remain
controversial because of their deep location, tortuosity, and fragility
[7]. Peripheral aneurysms originate mainly from the lenticulostriate
artery, thalamic perforating artery, or choroidal arteries [8].
Previous reports have described aneurysms treated with close
observation, direct clipping, endovascular coiling, or direct
revascularization [6].
Herein, we report the case of a patient with Moyamoya disease that
rapidly developed an MMD-associated pseudoaneurysm after direct
revascularization. The patient recovered after endovascular coiling, and
secondary revascularization was performed.