**1. Introduction**

Blister aneurysms are a rare but well-recognized form of cerebral vascular lesions. Comprising less than 2% of all intracranial aneurysms, they are typically found on the dorsal or dorsomedial wall of the internal carotid artery (ICA). With a characteristic thornlike appearance on angiography, blister aneurysms' most prominent feature is the fragility of their wall. This explains for their aggressive clinical course and grave prognosis.

Although most authors agree that blister aneurysms are either dissecting or false lesions, their exact nature as well as their optimal management remains unknown. Traditionally, surgery has been advocated as the first-line treatment. Primary clipping, wrapping, wrap-clipping or even carotid artery sacrifice (with or without a bypass) have all been tried. However, results have always been far from satisfying, often making neurosurgeons reluctant to operate on such cases.

During the past few years, clinicians' interest in blister aneurysm has been renewed with the introduction of endovascular modalities in everyday practice. Among all the different available approaches, flow diversion seems lately to be gaining ground, showing promising results. Of course, until consensus has been reached, blister aneurysms are still to be treated on a case-by-case basis.
