Orbital Complications resulting from Pseudomonal Infection of a Pneumatized Anterior Clinoid Process: A Case Report

Objective: To describe a rare cause of acute isolated sphenoid sinusitis in an adult, immunocompetent, female, complicated by meningitis due to a clival abscess and subsequent development of orbital apex syndrome, originating from an infected pneumatized anterior clinoid process (ACP) Methods: We present a case report of a 61-year-old, healthy, female, who presented with a one-week history of fever, upper respiratory tract infection symptoms, and severe headache. Initial computed tomography (CT) of the head revealed isolated sphenoid sinusitis with posterior wall dehiscence communicating with the prepontine subarachnoid space. She underwent an endoscopic transseptal repair of the clival defect with a nasoseptal flap, followed by a three-week intravenous antibiotic regimen. Apart from consistent headaches, her postoperative course was unremarkable. Four months later, she presented with orbital apex syndrome. Magnetic resonance imaging (MRI) revealed mucosal disease in a pneumatized ACP. She underwent a second surgical intervention including a left-sided sphenoidectomy, orbital and optic canal decompression. Results: Initial surgical management successfully addressed the intracranial infection. However, persistent headaches and delayed onset of orbital apex syndrome occurred despite unremarkable interim imaging and endoscopy. A gadolinium-enhanced MRI ultimately identified inflammation within the pneumatized ACP, when the patient presented with orbital apex syndrome. Intraoperative cultures during the second surgery grew Pseudomonas, for which she underwent prolonged intravenous antibiotic therapy. There has been marked improvement in her symptoms, with a remaining mild sixth cranial nerve palsy and postnasal drip at her most recent follow-up. Conclusion: Isolated sphenoid sinusitis, especially involving a pneumatized ACP, can present insidiously and lead to serious intracranial and orbital complications despite early intervention. High clinical suspicion and early use of MRI are essential in patients with persistent symptoms and subtle imaging findings. Multidisciplinary management and long-term follow-up are crucial for optimal outcomes.