Abstract Introduction Supraclinoid ICA aneurysms, located proximal to the dural sheath, are rare but serious vascular anomalies that increase in prevalence with age and are more common in women. These aneurysms are classified based on their anatomical relation to the ophthalmic, posterior communicating (PCom), or anterior choroidal arteries. This case describes a young woman presenting with acute oculomotor palsy, revealing an underlying PCom artery aneurysm, and emphasizes the urgency of early recognition and treatment to prevent catastrophic outcomes. Description A 32-year-old female with no prior medical history presented to the emergency department with a four-day history of generalized headache and double vision. Examination revealed right-sided ptosis, mydriasis, and diplopia, indicative of third cranial nerve palsy. Her NIH Stroke Scale score was 2. Non-contrast head CT was negative for hemorrhage, but CT angiography revealed a 5 mm right PCom artery aneurysm (figure 1), confirmed by brain MRI. The patient underwent diagnostic cerebral angiogram and successful endovascular coiling; however, diplopia and ptosis persisted at the one-month follow-up. Discussion The supraclinoid segment of the ICA is anatomically proximate to the oculomotor nerve. PCom artery aneurysms frequently cause third nerve palsy due to direct compression, with mydriasis being a hallmark sign resulting from the involvement of parasympathetic pupillomotor fibers. While the annual rupture risk for PCom artery aneurysms is low (0.46%), symptomatic presentation, as in this case, suggests increased instability and a heightened risk of subarachnoid hemorrhage. Endovascular coiling is a preferred treatment for anatomically suitable PCom artery aneurysms, offering favorable outcomes when performed promptly. In this case, the four-day delay in presentation and significant initial neurological findings likely contributed to the lack of symptom resolution post-intervention. This outcome highlights the time-sensitive nature of managing symptomatic aneurysms and the need for heightened clinical suspicion in young adults presenting with acute headache and cranial nerve deficits. Comprehensive neurovascular imaging, including CTA or MRI, is critical for timely diagnosis and risk stratification. This abstract is funded by: None
Jawed et al. (Fri,) studied this question.