Complete penetration of the optic chiasm by an unruptured aneurysm of the ophthalmic segment: case report.

BACKGROUND: It is well known that aneurysms of the ophthalmic segment sometimes elevate the optic nerve or chiasm, and in case of large or giant aneurysms, the optic apparatus can be dramatically thinned. Nonetheless, they rarely penetrate the optic pathway completely. To our knowledge, no previous reports have dealt with the complete penetration of the optic chiasm by unruptured aneurysms of the ophthalmic segment. CASE DESCRIPTION: A 70-year-old woman presented with visual dysfunction in her left eye that she had experienced for several months. Her left visual acuity had rapidly deteriorated to the level of finger counting and visual field testing demonstrated nasal hemianopsia in the left eye and upper temporal quadrant hemianopsia in the right eye. Left internal carotid angiograms and three-dimensional digital subtraction angiograms showed an aneurysm of the ophthalmic segment projecting superomedially. Intraoperative findings revealed complete penetration of the optic chiasm by the fundus of the aneurysm. The optic pathway adjacent to the dome had become remarkably thin and dark yellow. After clipping was completed, the fundus of the aneurysm was punctured to decompress the optic chiasm. Postoperatively, patient's visual acuity in the left eye gradually recovered, but the visual field deficit persisted after the operation.
CONCLUSION: This rare case demonstrates the potentially aggressive behavior of unruptured aneurysms of the ophthalmic segment. Patients with unruptured aneurysms of the ophthalmic segment who present with visual symptoms should be treated with surgical clipping to decompress the optic pathway as soon as possible.