Skull Base Involvement in Covid Associated Rhino-Orbital-Cerebral Mucormycosis: A Comprehensive Analysis

The base of skull forms the first line of barrier to be breached in the transition of rhino-orbito-palatal forms of mucormycosis to intracranial forms with various neurological deficit. The pattern of base of skull erosion has prognostic implications in overall recovery and survival of the patient. The aim of the study was to assess the pattern of skull base involvement in cases of rhino-orbital-cerebral mucormycosis (ROCM) in terms of clinical presentations, radiological findings, intraoperative illustrations and post operative recovery. This is a retrospective single centre study of Covid associated Mucormycosis (CAM) patients with skull base involvement at a tertiary referral centre of central India from May 2021 to October 2021. Amongst a total of 248 patients of CAM, 54 patients with skull base involvement were included in our study. The cases were stratified into basifrontal-BF (15%), basisphenoid-BS (20%), orbital apex-OA (15%), basiocciput-BO (26%), frontal bone osteomyelitis-FBO (22%) and sphenoid bone osteomyelitis-SBO (2%), based on their pattern of involvement of skull base and intracranial spread. Early ethmoid and cribriform plate involvement progressed to frontal lobe abscess while early maxillary disease progressed to developed temporal lobe abscess. The orbital apex lesions had early onset cavernous sinus thrombosis. Analysis of clinical manifestations and postoperative follow up revealed an emerging pattern where Posterosuperior lesions of paranasal sinuses (Ethmoid, roof of maxilla and orbit) progressing to BF, BS, OA, FBO and SBO had poorer treatment outcome than Anteroinferior (Floor of maxillary sinus, palate) based lesions which involved BO of skull base. The inferiorly located diseases had better prognosis, less duration of hospital stay, lesser mortality and decreased need for second surgery. There exists a temporal relation of the initial site of fungal load in sinonasal region to their subsequent intracranial spread. Classification into subtypes helped in disease stratification which helped in prognostication and surgical planning. Early intervention by multidisciplinary team improved survival outcome.