To describe and illustrate with neuroimaging the progression of rhino-orbital-cerebral mucormycosis leading to orbital apex syndrome, cranial neuropathies, cavernous sinus thrombosis, and strokes from internal carotid artery steno-occlusive disease.

A 67-year old female with uncontrolled diabetes mellitus presented with progressive vision loss in the right eye and right sided facial weakness, associated with fatigue and fevers. She underwent intranasal debridement, and hematoxylin and eosin staining showed broad-based, branching, non-septate hyphae, consistent with mucormycosis. She was treated with antifungals.

She sought care again 3 months later, at which point she had no vision in the right eye, and was unable to open or move the right eye. Her examination at this point was notable for no light perception in the right eye with mid-size, unreactive pupil; complete ptosis and ophthalmoplegia of the right eye; and right facial weakness in a lower motor neuron pattern. Magnetic resonance imaging of the brain demonstrated inflammation at the orbital apex, as well as thromboses of the right superior ophthalmic vein and right cavernous sinus. 

Despite treatment with systemic antifungals and anticoagulation, the patient later developed sudden-onset lethargy associated with a right gaze deviation. She was found to have severe stenosis of the bilateral intracranial internal carotid arteries on cerebral angiogram. Magnetic resonance imaging showed interval development of bilateral deep watershed territory infarcts. 

Mucormycosis is a rare but devastating fungal infection caused by mucormycetes, which are ubiquitous in nature. Most patients with invasive mucormycosis are immunocompromised, classically due to poorly controlled diabetes or hematologic malignancies. Mucormycosis spreads contiguously through the sinuses, and is also angioinvasive. Because the infection typically begins as a rhinosinusitis, the fungus spreads intracranially through direct invasion of the cavernous sinus. This case and the associated imaging illustrates the stepwise progression of mucormycosis due to contiguous spread intracranially.