Microsurgical clipping for anterior communicating artery aneurysm associated with the accessory anterior cerebral artery via the pterional approach

BACKGROUND: Accessory anterior cerebral artery (ACA), a type of median artery of anomalous triplicate ACA, is not rare, but aneurysms of the anterior communicating artery (ACoA) associated with accessory ACA can be a considerable challenge to treat surgically based on the morphological features of the ACoA complex. CASE DESCRIPTION: A 35-year-old man was admitted to our hospital with severe headache and subsequent loss of consciousness. Initial computed tomography (CT) showed typical findings of subarachnoid hemorrhage in the basal cistern and three-dimensional CT angiography revealed an ACoA aneurysm arising from the trifurcation of the accessory ACA, the branching point of the ACoA, and the right A1 or A2 segment of the ACA. The aneurysmal fundus projected superolaterally to the right, and was treated via a right-sided pterional approach. The aneurysm was behind the ipsilateral A2 segment of the ACA and the accessory ACA was hidden behind the aneurysm. The aneurysm was successfully obliterated with clipping using a straight fenestrated Yasargil titanium clip. Complete aneurysm occlusion and patency of both the A2 segment of the ACA and the accessory ACA were confirmed intraoperatively by indocyanine green angiography. CONCLUSION: In treating this aneurysm via the pterional approach, selection of approach side it is critical to preserve prevent the patency of the accessory ACA and to simultaneously perform aneurysm clipping without leaving a neck remnant. Selecting the optimal approach based on preoperative neuroimaging of which side will allow both these actions is important.