The Sinus Snare: A Case Series of Isolated Sphenoid Sinusitis Presenting as Orbital Apex Syndrome in Poorly Controlled Diabetes.

Isolated sphenoid sinusitis is an uncommon entity, accounting for a small proportion of paranasal sinus disease. Its deep anatomical location and proximity to the optic nerve, cavernous sinus, and orbital apex often result in delayed diagnosis, particularly when typical nasal symptoms are absent. In poorly controlled diabetics, fungal infection of the sphenoid sinus can progress rapidly, presenting initially with ophthalmic deficits rather than sinonasal complaints. This series describes three female patients between 50 and 53 years of age, all with long-standing type 2 diabetes mellitus with irregular treatment compliance. Each patient presented primarily with visual disturbance: the first with gradual blurring of vision and mild proptosis; the second with acute-onset ptosis, proptosis, and diplopia indicative of orbital apex syndrome; and the third with isolated lateral gaze diplopia due to abducens nerve palsy. Nasal symptoms were minimal or absent in all three cases. Imaging demonstrated isolated sphenoid sinus involvement, and diagnostic nasal endoscopy revealed subtle posterior drainage signs. Endoscopic sphenoidotomy was performed in all patients. Histopathology confirmed mucormycosis in one patient and Aspergillus fungal sinusitis in another. Postoperative outcomes were favorable, with all three patients achieving improvement of visual acuity to 6/6 and complete resolution of ophthalmoplegia where present. This case series emphasizes that visual symptoms in diabetics may be the earliest manifestation of sphenoid sinus disease. Early radiologic evaluation and prompt endoscopic surgical intervention, coupled with appropriate antifungal therapy, are essential to prevent permanent optic nerve injury and ensure favorable neurological and visual outcomes.