Cerebral aneurysms causing visual symptoms: their features and surgical outcome.

Cerebral aneurysms causing visual symptoms before surgery are relatively rare. We have experience with 17 cases of such aneurysms and report their clinical features and surgical outcome. The locations of aneurysms presenting with visual dysfunction in our series are as follows: internal carotid (IC)-cavernous aneurysms in six of 29 total cases, 21%; IC-ophthalmic aneurysms in nine of 36 total cases, 25%; and anterior communicating artery (A com A) aneurysms in two of 217 total cases, 1%. The size of the aneurysms, the period between the onset of symptoms and surgical treatment, the pre- and post-operative visual function, and the surgical methods used to treat the aneurysm were analyzed. All the visually symptomatic cases featured large (15-24 mm) or giant (> 25 mm) aneurysms. Visual symptoms occurred before aneurysmal rupture in all cases but one. The type of visual field defect and the degree of reduced visual acuity were highly variable, without a typical clinical presentation. Five out of six IC-cavernous aneurysms were treated surgically with common carotid artery (CC) ligation or IC ligation with superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis. Three of these cases showed improvement of visual symptoms after surgery. Six out of nine IC-ophthalmic aneurysms were treated surgically (CC ligation or direct clipping), with four cases showing improvement of visual symptoms after surgery. One case of an A com A aneurysm featured a ruptured aneurysm that had physically penetrated the optic chiasm, while the other case was a giant unruptured aneurysm. The interval between the onset of symptoms and surgical treatment was the only factor identified which affected the clinical outcome of the aneurysms presenting with visual dysfunction. All cases that were determined to show improvement of visual function were treated surgically within 3 months of the onset of symptoms. Cerebral aneurysms presenting with visual dysfunction before surgery are most commonly large or giant, and unruptured. Recovery of visual function can most often be expected when surgical treatment is performed expeditiously, before the visual dysfunction becomes irreversible.