Orbital compartment syndrome in orbital mucormycosis: spot the threat through radiologist's eye.

PURPOSE

To illustrate the imaging findings of orbital compartment syndrome (OCS) in patients with orbital mucormycosis and to identify the red flag signs on imaging for prompt diagnosis and timely intervention.

METHODS

We conducted a retrospective analysis of CT and MRI scans from patients diagnosed with sino-nasal mucormycosis within three months of a confirmed COVID-19 infection. Microbiologically proven cases of mucormycosis were included. Images were analysed for: Route of spread; proptosis; tenting of globe, Retro-orbital fat/extraocular muscle (EOM) nonenhancement; Intra-orbital abscess, superior ophthalmic vein (SOV) thrombosis, stretching/thickening/enhancement/diffusion restriction of optic nerve, orbital coat, and EOM. Descriptive statistics were elaborated in the form of mean/standard deviations for continuous variables and frequencies and percentages for categorical variables.

RESULTS

Out of 138 patients with mucormycosis, 49 had orbital involvement, OCS was present in 16 orbits. The mean age was 48.6 years with M: F of 2.75:1. Adjacent sinuses were involved in all patients. Spread along nerves and nasolacrimal duct was seen in 94% patients. Globe tenting was seen in all and thickening/coat enhancement in 53.3%. Optic nerve (ON) was thickened in 87.5%, diffusion restriction of ON and EOM in 78.5% cases. Non enhancement of retro-orbital fat was seen in 50% and intra-orbital abscess in 62.5% cases.

CONCLUSIONS

OCS is a vision-threatening orbital emergency, leading to OIS and permanent blindness, if not managed promptly. Imaging features that warrant immediate clinical/ surgical intervention to avoid permanent loss of vision are distorted globe, posterior tenting of the globe, stretching of the optic nerve, non-enhancement of retro-bulbar fat and extra-ocular muscles (EOMs).