Less Invasive Techniques to the Optic Nerve in Aneurysm Surgery

Direct surgery of paraclinoid aneurysms that could require anterior clinoidectomy for exposure, or of some basilar head aneurysms that could require going deep through the opticocarotid triangle for access, may injure the optic nerve. And also in surgery of large or giant aneurysms of the internal carotid artery that could compress the optic nerve, recovery and preservation of visual function, or sometimes even prevention from the worse, could become important issues. We describe less invasive surgical techniques in surgery of aneurysms that may injure the optic nerve, based on our experience in 36 cases selected from among 528 aneurysm surgeries of the past 11 years. The safe and easy method of anterior clinoidectomy that includes the following components may be useful: 1) drilling of the orbital roof, the lateral part of the anterior clinoid process and the optic canal should be performed though the extradural route, and 2) removal of the residual apex of the anterior clinoid process should be completed after moving to subdural space when the dura covering the process has been cut and pealed off. A longer cut of the falciform ligament could be useful to make the optic nerve movable and to widen the opticotriangle space. A suction decompression technique for large and giant aneurysms should effectively ensure safe clipping near the optic nerve.