Penetration of the Optic Nerve or Chiasm by Anterior Communicating Artery Aneurysms: Three Case Reports

Although large and giant aneurysms can induce visual disturbance by compression of the anterior visual pathway, splitting and penetration of the optic apparatus are extremely rare. The authors describe three patients who underwent clipping surgery for anterior communicating artery aneurysm infiltrating into the optic nerve or chiasm. These findings were suspected on preoperative magnetic resonance imaging and confirmed at surgery. Two aneurysms were ruptured and one unruptured. The authors review the literature and discuss the mechanism of cranial nerve penetration by an aneurysm.