Acute formation of a pseudoaneurysm adjacent to a previously clipped anterior communicating artery aneurysm.

Background: Cerebral pseudoaneurysms, especially of the anterior communicating artery (ACoA), are rare.

Methods: Herein, the authors report a 66-year-old patient who underwent successful clip ligation of a small ruptured ACoA aneurysm. Eighteen days after surgery, he suffered from another episode of subarachnoid hemorrhage due to the rupture of a newly formed pseudoaneurysm adjacent to the previously clipped aneurysm. This pseudoaneurysm was treated through clip ligation as well.

Conclusions: A pseudoaneurysm may rarely form adjacent to a previously clipped cerebral aneurysm and should be included in the differential diagnosis of recurrent subarachnoid hemorrhage. Potential mechanisms of formation and management strategies for this challenging problem will be discussed.