Spontaneous Angiographic Disappearance of an Intracranial Aneurysm: A Systematic Review of Cases in the Last Ten Years and Two Cases from Our Institution.

Spontaneous disappearances of intracranial aneurysms have been reported previously, but because of their rarity, discussing their pathophysiology has been difficult. This study aims to investigate cases of spontaneous angiographic disappearance of intracranial aneurysms over the past 10 years, including two additional cases from our hospital, and determine their clinical significance. PubMed was searched for articles on the spontaneous disappearance of intracranial aneurysms published within the last ten years. Data on patient demographics, characteristics of the aneurysms (ruptured or unruptured, location, size, and shape), and the time to the disappearance, recurrence, with or without vasospasm, and treatment were collected. Additionally, two cases from our hospital (Cases A and B) were analyzed. In total, 11 articles with 12 cases of spontaneous aneurysm disappearance were chosen for analysis. Of these cases, 10 occurred in females, and the age of the affected patients ranged from 7 months to 72 years. Eight cases involved unruptured aneurysms, which were larger and took longer to disappear. Three patients experienced a recurrence during the observation period. Several differences were found between the characteristics of the previous cases and those of our case XIII in Table 1 (Case A). In conclusion, spontaneous angiographic disappearance involves complex interactions between thrombosis, vasospasm, and endothelial remodeling. Exceptions were noted, emphasizing the need for nuanced considerations in elucidating the mechanisms behind aneurysm disappearance. The recurrence of aneurysms that had disappeared highlights the importance of the following treatment, if clinically indicated, urgent neurosurgical intervention should be considered; otherwise, thorough angiographic monitoring at least.