The clinical reality of "disappeared" lateral posterior choroidal artery aneurysm: case report.

Spontaneous disappearance of aneurysms, undetectable by conventional angiography, has been reported. This case report presents a patient with ventricular hemorrhage secondary to a ruptured lateral posterior choroidal artery aneurysm, confirmed by digital subtraction angiography (DSA). Without any intervention, follow-up DSA 11 months later showed an apparent "disappearance" of the aneurysm. However, high-resolution magnetic resonance vessel wall imaging revealed that the aneurysm had not indeed disappeared but had thrombosed, leading to a negative DSA appearance. By directly visualizing the vessel wall and intraluminal structures, magnetic resonance vessel wall imaging provides a valuable tool for the diagnosis and follow-up of negative aneurysms on DSA, enabling early detection of intraluminal thrombus formation.