Penetration and splitting of the optic apparatus by intrasaccular coils within an anterior communicating artery aneurysm.

Penetration of the optic apparatus by an anterior communicating artery (ACoA) aneurysm is unique. A 43-year-old woman with a history of visual disturbance due to a previous aneurismal rupture underwent surgical neck clipping for a recurred ACoA aneurysm, which had previously been treated using detachable coils. The operation confirmed that the recurred aneurysm and the packed coils had penetrated the chiasm and the right optic nerve (ON), which was distorted and thinned. The aneurismal neck was clipped and the coils were left in place because damage to the optic apparatus by penetration is usually irreversible. As the patient was semicomatous at the former admission due to subarachnoid hemorrhage (SAH), she became aware of the visual disturbance 2 weeks after ictus when she had improved enough to communicate. The visual disturbance was found to have gradually improved at her 1-year follow-up. The absence of visual symptoms before the SAH and gradual visual improvement after coiling, even after recurrence due to coil compaction, were considered more compatible with a chronic compensated compressive, penetrating lesion of the ON.