Perineural spread in invasive fungal sinusitis: Underrecognized complication of head and neck invasive fungal infection

Background: Peri-neural spread of fungal infection is a potentially fatal condition. Identification of the major risk factors, as well as rigorous analysis of clinical features and radiological findings, may improve the chances of prompt diagnosis and better patient outcome.Aim of the work: In this study we pursue to investigate perineural spread in patients with invasive fungal infection. Patients and Methods: An institutional Review Board (IRB) approved retrospective study was conducted between April 2021 and October 2022 on 17 patients (10 male and 7 female) presented with clinical concern of fungal sinusitis and suspected perineural spread. The patients have performed contrast enhanced MRI and CT examination to evaluate sites of peri-neural extension, the involved cranial nerves, and the anatomical location. Histopathological data were obtained through surgically excised specimens in all cases. Results: In our study, the peri-neural spread was found with involvement of pterygopalatine fossa (PPF) (16 cases) (94.1%), foramen rotundum (FR) (13 cases) (76.5%), vidian canal (VC) (two cases) (11.8%), Meckel’s cave (MC) (10 cases) (58.8%), cavernous sinus (CS) (8 cases) (47%), main trigeminal nerve till pons (two cases) (11.8%), 16 out of 17 cases (94.1%) showed involvement of maxillary division of trigeminal nerve (V2) and to lesser extent ophthalmic division (V1) (only 1 case) and mandibular division (V3) (6 cases) at infra-temporal fossa. Conclusion: Peri-neural spread can occur in invasive fungal infections, and most commonly along the anatomical distribution of trigeminal nerve and its branches “especially V2”.