Bilateral Fornical Columns Infarction Secondary to an Arteriovenous Malformation Embolization

Three group of perforation branches are described coming out from the anterior communicating artery (AcoA): the hypothalamic branches, chiasmatic branches, and subcallosal artery (ScA). Bilateral anterior fornix infarction with sudden anterograde amnesia after ScA ischemic stroke has been previously described. Although only a few cases are reported in the literature, ScA occlusion has been well described for both noniatrogenic and iatrogenic causes. Several cases of iatrogenic injuries have been reported after AcoA aneurysm clipping or, less frequently, after embolization.

A 43-year-old man was admitted for a subarachnoid hemorrhage secondary to the rupture of a right high-flow anterior cerebral artery (ACA) aneurysm related to a right frontobasal arteriovenous malformation (AVM). The aneurysm was treated early by endovascular embolization. At discharge, the patient was Glasgow Outcome Scale score 1. Five months later, the AVM was treated endovascularly in 3 sessions. The last session was performed through a median branch of the right A2 segment of the ACA, allowing an 80% AVM exclusion. However, the patient woke up with anterograde memory impairment and confusion. Magnetic resonance imaging showed infarction of both anterior columns of the fornix. The clinical condition of the patient 3 years after stroke has improved.

Bilateral anterior fornix infarction leading to amnestic syndrome is encountered in ScA stroke. We report a rare case of bilateral anterior fornix infarction secondary to an AVM embolization supplied by the ACA, not an anatomic region that provides blood supply of the anterior columns of the fornix.