A Case of a Repeatedly Missed Aneurysm in a Patient With Third Nerve Palsy

Medically complex presentations may pose a diagnostic challenge for providers, highlighting the need for inter-team communication and independent imaging review. We report a single case in which the patient presented with cranial nerve III palsy from a posterior communicating artery (PCOM) aneurysm that was missed on three separate angiographies. The patient initially presented with an incomplete cranial nerve (CN) III palsy and had workup and treatment for giant cell arteritis (GCA). Three months later, she presented again with worsened, complete CN III palsy. Upon independent review of CT and MRI angiography by the ophthalmology and neuro-radiology team, an 8 mm aneurysm of the right internal carotid artery (ICA) adjacent to the posterior communicating artery (PCOM) (initially missed) was identified. The patient was treated with percutaneous coil embolization, which resulted in partial recovery of her CN III function. This case demonstrates the importance of maintaining a high index of suspicion, independently reviewing radiologic imaging, and inter-team discussion.