Anterior Choroidal Artery (AChA) Aneurysm Mimic: Duplicated AChA with Dual Infundibulum

Introduction: Anterior choroidal artery (AChA) aneurysms account for 2–5% of all intracranial aneurysms. Modern neurologic morbidity from the open treatment of AChA aneurysms remains significant, with ∼12% of patients suffering a partial or complete AChA syndrome, comprised of hemiparesis, hemianopsia, and/or hemisensory loss. A thorough understanding of anatomic variants is essential for the safe obliteration of these challenging aneurysms. Here, we report a case of a duplicated AChA where both braches arise from an infundibulum, a variant which has never been reported.

Case Description: This 34 year old woman presented 2 years ago to our institute with an acute subarachnoid hemorrhage due to a ruptured anterior communicating artery aneurysm which was treated with endovascular techniques. She made an excellent recovery. She was found to also harbor bilateral AChA aneurysms: a 2 mm smooth-domed, wide-based left AChA aneurysm which we are observing and a 4 mm irregularly-shaped/bilobed, wide-based right AChA aneurysm, with the AChA arising from the aneurysm dome, for which we recommended surgical clipping. At surgery, after initial clip placement, two AChA arteries were identified arising from a common ICA origin with each AChA associated with an infundibulum. The clip was removed, the area explored and surgical video stored. The artery at the junction of the two infundibula appeared thin and slightly irregular, and wrapped with cotton. Motor and somatosensory evoked potentials remained normal throughout the procedure and she awoke without a neurological deficit. One AChA was dimunitive, perhaps not resolvable even with modern digital subtraction angiography, accounting for the apparent bilobed appearance of this 'aneurysm.'

Discussion: Duplicated AChA are exceedingly rare. The only prior observation known to these authors was made by Rhoton et al. in 1981. Small ICA terminus perforating arteries are known to supply the anterior perforated substance and these can arise from the dorsal carotid in the region of the AChA. All of these branches must be protected during clipping of AChA aneurysms.

Conclusion: In this case, a thorough dissection of this apparently bilobed AChA aneurysm allowed for identification of this unusual anatomic variant and preservation of both (duplicated) AChA branches and associated infundibula.