Large Posterior Communicating Artery Aneurysm: Initial Presentation with Reproducible Facial Pain Without Cranial Nerve Deficit.

Unruptured posterior communicating artery (PCOM) aneurysms can be difficult to diagnose and, when large (≥ 7mm), represent a substantial risk to the patient. While most unruptured PCOM aneurysms are asymptomatic, when symptoms do occur, clinical manifestations typically include severe headache (HA), visual acuity loss, and cranial nerve deficit. This case report describes an atypical initial presentation of a large unruptured PCOM aneurysm with symptoms mimicking trigeminal neuralgia, without other associated cranial nerve palsies or neurologic deficits. The patient returned to the emergency department four days later with a HA, trigeminal neuralgia, and a new cranial nerve III palsy. After appropriate imaging, she was found to have a large PCOM aneurysm, which was treated with surgical clipping with significant improvement in patient's symptoms.