October 20, 2016
A 65-year-old woman with diabetes and a 4-day history of altered level of consciousness, right orbital swelling, monocular vision loss, and right III-VI cranial nerve palsy
Invasive Fungal Sinusitis with Optic Nerve Ischemia
- Background:
- Acute invasive fungal sinusitis is a rapidly progressing infection seen predominantly in immunocompromised patients and patients with poorly controlled diabetes.
- The nasal cavity is the primary site of infection, with the middle turbinate accounting for two-thirds of positive biopsy results.
- Clinical Presentation:
- Rapid development of fever, facial pain, nasal congestion, and, less frequently, epistaxis
- Extrasinusal extension into the orbit, cavernous sinus, or intracranial compartment is frequent and results in deterioration in vision, proptosis, and neurological deficits, respectively.
- Key Diagnostic Features:
- CT and MRI demonstrate mucosal thickening of involved PNS and nasal cavity bone destruction.
- The involved mucosa is necrotic with no enhancement and referred to as “black turbinate sign”.
- Occlusion of the ophthalmic and central retinal artery leads to optic nerve ischemia, seen as optic nerve restricted diffusion.
- Differential Diagnoses:
- Anterior ischemic optic neuropathy: 2 types; arteritic variety—the most common cause is giant cell arteritis; non-arteritic variety—vascular risk factors are common in this population
- Posterior ischemic optic neuropathy: sudden onset of color blindness, hypertension, and diabetes
- Traumatic optic neuropathy: the clinical history is frequently available and associated fractures and soft tissue swelling are usually seen.
- Cavernous sinus thrombophlebitis: no enhancement and lateral bulging of the involved sinus is seen.
- Treatment:
- Extensive surgical debridement and systemic antifungal therapy
- There is no specific treatment for the ischemic optic neuropathy in this scenario.
