Invasive Sino-orbito-cerebral mycosis- An Overview

INTRODUCTION Although fungal rhinosinusitis is a rare disorder but number of cases on record has increased manifold during the last decades worldwide There are two basic types of fungal rhinosinusitisinvasive and non-invasive. The invasive form may be of acute invasive and chronic invasive. The non-invasive fungal rhinosinusitis can be of three typesfungus balls or mycetomas, saprophytic colonization and allergic fungal rhinosinusitis. Invasive fungal sinusitis (IFS) is one of the important cause of morbidity and mortality in immunocompromised patients. Invasive fungal sinusitis (IFS) is commonly seen in uncontrolled diabetics, debilitated, chronic renal failure, haematological dyscrasias, immunocompromised patients such as those receiving high doses of chemotherapy for malignancy, using long term immuno-suppressive drug after organ transplantation and those suffering from immuno-suppressive diseases such as AIDS. Invasive fungal sinusitis is caused by predominantly two classes of fungi Mucor and Aspergillus. The literature has only 12 reported cases of mucormycosis for all organs in AIDS patients. The yeast such as Candida albicans may cause this disease, and Aspergillus flavus and Aspergillus fumigatus being most widely isolated molds. IFS caused by Zygomyces like Rhizomucor, Rhizopus and Mucor, has also been observed. 8-10, 12, 13, 17-20 Moreover, IFS can be characterized by a rapid vascular spread from the nasal and sinus mucosa into the orbit, skull base and brain. In comparison to the non-invasive type which usually has a good prognosis, IFS is considered to be a potentially lethal condition. In India, initially the disease was prevalent only in north India but now reported from other parts of the country as well. Though species of Aspergillus is isolated from majority of such cases, Dematiaceous hyphomycetes, Pseudallescheria boydii, Candida species, Fusarium species are also reported from some cases. Chronic indolent invasive sinusitis is more slowly destructive, usually occurring in more immunologically normal patients. Mucormycosis refers to a spectrum of diseases caused by order of mucorales, disease was first described by Meyer 1815. In humans the most common causative agent being of the rhizopus species. Mucorales are predominantly found on decaying organic material and also act as opportunistic pathogens causing an acute angioinvasive infection seen primarily in the immunocompromised. Baker introduced the term ''rhinocerebral mucormycosis'' as a malignant form of cephalic mucormycosis with a high mortality rate. Mucormycosis is an infrequent disease with an annual incidence of 0.4–1.7 cases/ 1,000,000 population and worldwide distribution..