Posterior ischemic optic neuropathy with acute monocular vision loss following clipping of anterior communicating artery aneurysm. A case report and review of literature

BACKGROUND: The acute postoperative monocular vision loss following anterior communicating artery aneurysm clipping secondary to posterior ischemic optic neuropathy (PION) a rare presentation. CASE DESCRIPTION: A 32-year old patient presented with a spontaneous holocranial thunderclap headache for 7 days, associated with vomiting. The SAH was diagnosed with a tiny saccular aneurysm arising from the anterior communicating artery. A left pterional craniotomy and clipping of aneurysm were done. On the 3(rd) postoperative day, he complained of left-sided complete blindness, and on the 5(th) postoperative day, his GCS dropped to E4V1M5 with right-sided hemiplegia. MRI brain showed normal optic apparatus with bilateral ACA and left MCA territory infarct. CONCLUSION: The PION must be kept in the differential diagnosis of post-clipping sudden visual deterioration, especially following anterior communicating artery aneurysm rupture.