Perianeurysmal parenchymal cysts – Case series and literature review

•Intracranial cysts are associated with a number of vascular lesions.•They predominantly occur in larger, partially-thrombosed aneurysms and in older patients.•There is a trend towards enlargement over time if untreated and a likelihood of recurrence following treatment.•We hypothesise the cysts arise either from dilated Virchow-Robin spaces and/or inflammatory processes.