Hyperbaric Oxygen Therapy in Sinonasal Disease: Mechanisms, Clinical Evidence, and Multidisciplinary Perspectives on Invasive Fungal Rhinosinusitis and Post-Radiotherapy Injury

Background. Hyperbaric oxygen therapy (HBOT) delivers 100% oxygen at supra-atmospheric pressure, producing tissue hyperoxygenation, enhanced phagocytic killing, neoangiogenesis, and immunomodulation. Although HBOT is well established in head-and-neck practice, its specific role in sinonasal disease remains poorly systematised. Objective. To reappraise the rationale, evidence, and practical implementation of HBOT in two cardinal sinonasal indications—acute invasive fungal rhinosinusitis (AIFRS) and post-radiotherapy sinonasal damage—through a rhinology-centred, multidisciplinary lens. Methods. Narrative review of articles published in PubMed/MEDLINE, Scopus, Embase, and the Cochrane Library between 1 January 1980 and 31 March 2026, conducted following the SANRA framework and combining MeSH terms for HBOT with sinonasal, mucormycosis, osteoradionecrosis, and skull-base keywords. Results. In AIFRS, HBOT addresses the angioinvasive ischaemic core, restores oxidative neutrophil killing, and potentiates amphotericin B; observational data—including the recent COVID-19-associated mucormycosis (CAM) experience—suggest a survival benefit when HBOT is added early to surgical and antifungal therapy. In post-radiotherapy injury, HBOT reverses Marx's hypoxic–hypocellular–hypovascular triad, supporting healing of osteoradionecrosis (maxillary and skull-base), soft-tissue radionecrosis, and reconstructive procedures in the irradiated bed. Sinus barotrauma, the most frequent rhinological complication, is largely preventable with structured pre-treatment ENT assessment. Conclusions. HBOT is a mechanistically well-founded, well-tolerated adjunct with a favourable safety profile when delivered by a multidisciplinary team. Sinonasal-specific prospective registries and pragmatic randomised trials are urgently needed.