Three Cases of Unilateral Optic Nerve Neuropathy of Unknown Etiology after Aneurysm Surgery

Abstract

The incidence of unilateral optic nerve neuropathy after aneurysm surgery—except paraclinoid internal carotid artery (IC) aneurysm (AN)—is very rare. I experienced three cases of unilateral optic nerve neuropathy in my 431 cases of aneurysm surgery. I report on these three cases: a 58-year-old woman with an unruptured AN arising at the right middle cerebral artery, a 59-year-old woman with a ruptured AN arising at the left middle cerebral artery, and a 58-year-old man with an unruptured AN arising at the left IC. In each case, aneurysm clipping was successful in obliterating the AN and direct optic nerve injury seemed to be remote during surgery. All patients complained of reduced visual acuity and inferior hemianopia ipsilateral to the site of surgery, and an ophthalmological evaluation suggested they suffered ischemic optic neuropathy due to malcirculation of the posterior ciliary artery. Postoperative angiograms revealed an intact ophthalmic artery in each case. Optic nerve neuropathy in the three cases gradually improved during follow-ups of from two to 16 months. Although there are some possible etiological factors concerning optic nerve neuropathy, the pathophysiology of this optic nerve neuropathy after aneurysm surgery is unknown.
I speculate that even extremely careful surgical manipulation may have injured the surface of the optic nerve and/or the fine vasculature of the optic structures in two of the cases of unruptured ANs and, in addition, ischemia of fragile posterior ciliary artery due to delayed vasospasm seems to have been responsible for the damage of the optic nerve in the case of ruptured AN.