Microneurosurgical management of aneurysms of the A1 segment of the anterior cerebral artery: Anatomy and surgical technique

Abstract

Background: Aneurysms of the A1 segment of the anterior cerebral artery (ACA) are rare and have characteristics differentiating them from other intracranial aneurysms. Their microsurgical management is challenging and requires different strategies. In this article, we review the surgical anatomy of the A1 segment of the ACA with cadaveric dissections and describe the microsurgical management of complex A1 aneurysms with illustrative cases. Methods: A right pterional craniotomy and Sylvian dissection were performed on a formalin-fixed and silicone-injected cadaver head to depict the key anatomic structures and surgical corridors for microsurgical clipping of A1 segment aneurysms. The microneurosurgical management of ruptured and unruptured aneurysms of the A1 segment of the ACA is described with case illustrations. Results: The A1 segment of the ACA can be subdivided into proximal, middle, and distal subsegments, the former having abundant perforating branches. Both patients treated with microsurgical clipping had excellent and durable outcomes and postoperative cerebral angiograms showed complete aneurysm occlusion. Conclusion: Small A1 aneurysms may require early treatment as their rupture risk appears to be higher. A1 aneurysms are usually embedded in perforators, especially those arising from the proximal A1 subsegment, and require careful distal to proximal microdissection and strategic placement of the aneurysm clip blades. The approach, arachnoid dissection, and angles of attack are carefully planned after accounting for the aneurysm dome projection, precise location of the aneurysm neck and perforators, and the presence or absence of subarachnoid hemorrhage.

Beyond nimodipine: advanced neuroprotection strategies for aneurysmal subarachnoid hemorrhage vasospasm and delayed cerebral ischemia

“…The incidence of vasospasm in large series has been reported to be higher in medial and anterior circulation aneurysms [ 130 – 134 ], while lower rates have been observed in ruptured posterior cerebral artery aneurysms [ 135 ]. These findings have also been confirmed in the authors’ own series [ 136 – 145 ]. Nimodipine is the backbone in the prevention and treatment of vasospasm and ischemic related complications [ 11 , 146 , 147 ], it being the only medication approved by the US Food and Drug Administration and recommended by the AHA/ASA guidelines [ 12 ].…”

A Right-Sided Approach to Anterior Communicating Artery Aneurysms: A Case Review and Technical Report

“…Most perforators from A1 occur in the proximal portion of the A1 segment. Protection of these perforators can be done through careful preoperative localization, planning, and ensuring dissection occurs distal to proximal [ 14 ].…”

Case report: Endovascular coil embolization of an aneurysm at the origin of the accessory middle cerebral artery from the A1 segment as the collateral artery to twigs

“…Treatment is mandatory for ruptured aneurysms at the origin of the AccMCA; however, clipping may carry a risk of neurological complications because of the deep location and destruction of the collateral circulation ( 12 ). The International Subarachnoid Aneurysm Trial (ISAT) and its follow-up study confirmed the effect of endovascular coil embolization for ruptured aneurysms ( 13 , 14 ).…”