Lethal mycotic pseudoaneurysm presenting as isolated sixth nerve palsy

Abstract

Pseudoaneurysm of the internal carotid artery caused by skull base osteomyelitis (SBO) is a lethal condition seen in immunocompromised patients, predominantly those with diabetes mellitus. Cranial nerve involvement is a common complication and generally indicates a poor prognosis. We report the case of a 62-year-old diabetic patient who presented with isolated sixth cranial nerve palsy. She had uncontrolled blood sugar levels and high erythrocyte sedimentation rate, and she suffered from pyelonephritis.  Neuroimaging detected SBO with multiple secondary mycotic pseudoaneurysms prominent at the petrocavernous junction. Ischemia is the most common etiology for an isolated abducens nerve palsy, but in certain cases neuroimaging is warranted to prevent life-threatening complications. This case highlights the importance and urgency of identifying and managing such conditions.