Rhinocerebral mucormycosis: pathways of spread

Abstract

Rhinocerebral mucormycosis is an invasive, opportunistic fungal infection usually seen in immunocompromised patients, and particularly in the setting of diabetes or immune deficiency. It is assumed that the port of entry is colonization of the nasal mucosa, allowing the fungus to spread via the paranasal sinuses into the orbit. Involvement of the brain and cavernous sinus occurs by way of the orbital apex; therefore, spheno-ethmoidectomy with or without maxillectomy seems to be the definitive method to eradicate this infection. We conducted a prospective study of ten patients with rhinocerebral mucormycosis from February 2000 to April 2004. Rhinocerebral mucormycosis was clinically diagnosed in 11 patients, 10 of whom were included in our study upon histopathological confirmation. Diabetes was the most common underlying disorder seen in nine out of ten patients. In this study, the patients were assessed for predisposing factors, presenting signs and symptoms, sites of extension, the number and sites of surgical debridement, as well as the outcome. Ocular, sinonasal and facial soft tissue involvement was common. Involvement of the pterygopalatine fossa at the time of debridement was evident in all patients. No invasion through the lamina papiracea or the walls of the maxillary sinus was identified. At the time of this communication, six out of ten patients were alive. For the four who died, the causes were hypokalemia, cardiac arrythmia and refractory pneumonia. Pterygopalatine fossa is considered to be the main reservoir for rhinocerebral mucormycosis, and extension into the orbit and facial soft tissues usually follows this route. After proliferation in the nasal cavity, the mucor reaches the pterygo-palatine fossa, inferior orbital fissure and finally the retroglobal space of the orbit, resulting in ocular signs. The facial soft tissues, palate and infratemporal fossa can be infected through connecting pathways from the pterygo-palatine fossa; therefore, debridement of the pterygopalatine fossa seems to be the definitive method of managing this infection.