Eye Discomfort and Blurred Vision Preceding Oculomotor Nerve Palsy in a Warning Headache:A Case Report

Cerebral aneurysms can present with warning headaches before rupture or during minor leaks. Internal carotid artery-posterior communicating artery (IC-PC) aneurysms are among the few aneurysms for which the clinical observation of growth and associated symptoms is possible. Enlargement or morphological changes may worsen oculomotor nerve (ON) palsy, intensified headache, or orbital pain, indicating an impending rupture that requires urgent intervention. Notably, blurred vision with eye discomfort preceding ON palsy during impending rupture is rarely reported. Herein, we present a case highlighting this phenomenon. A 74-year-old woman with hypertension and migraines with aura presented with a 14-day history of gradual-onset left frontal headache. Despite the initial normal neurological findings and no evidence of subarachnoid hemorrhage on computed tomography, she later developed blurred vision and left eye discomfort without objective ON palsy. Her symptoms were initially attributed to migraines. Two days later, the patient developed ptosis and was diagnosed with complete ON palsy. Magnetic resonance angiography revealed a left IC-PC aneurysm, and urgent direct clipping confirmed rupture of the aneurysm. The patient recovered without complications. Blurred vision with eye discomfort during a warning headache may indicate early ON dysfunction and impending aneurysm rupture. Early recognition and vascular evaluation are crucial to prevent catastrophic outcomes. J. Med. Invest. 73 : 257-259, February, 2026.