Skull Base Osteomyelitis: A Systematic Review and Meta-Analysis of Epidemiology, Microbiology, Diagnosis, and Treatment Outcomes

Background: Skull base osteomyelitis (SBO) is a life-threatening infection arising predominantly from necrotizing external otitis, producing progressive osteitis of the temporal and central skull base. Originally described in elderly diabetic patients, its demographic profile has broadened to encompass immunocompromised hosts of diverse etiologies. Although historical mortality exceeded 50%, advances in imaging, microbiology, and antimicrobial therapy have improved prognosis substantially. Objectives: To systematically review the epidemiology, microbiology, clinical features, diagnostic modalities, therapeutic strategies, and outcomes of SBO and to identify evidence gaps requiring further investigation. Methods: A comprehensive search of PubMed/MEDLINE, EMBASE, Scopus, and the Cochrane Library (inception to March 2025, updated to March 2026) was performed. Studies reporting primary data on SBO (n >=5 patients) with defined diagnostic criteria, microbiological findings, treatment protocols, and outcome measures were included. Two independent reviewers screened records, extracted data, and assessed quality using the Newcastle-Ottawa Scale. Findings are presented as a narrative synthesis per PRISMA 2020 guidelines. For the outcomes most consistently reported in primary cohorts, a random-effects meta-analysis of pooled proportions (DerSimonian-Laird, logit scale) was additionally performed. Results: Forty-five studies encompassing 1,628 patients met inclusion criteria. The median patient age was 68 years (IQR 57–76); diabetes mellitus was present in 74.2%. Pseudomonas aeruginosa predominated (62.4%), with ciprofloxacin-resistant strains identified in 11.3% of post-2000 series. Fungal SBO, principally Aspergillus spp., accounted for 7.8% of cases and was consistently associated with higher mortality across reported series. Gallium-67 scintigraphy demonstrated the highest sensitivity (94%) for treatment monitoring; FDG-PET/CT sensitivity exceeded 96%. Combined fluoroquinolone-based therapy yielded a cure rate of 71.4%. Evidence for adjunctive hyperbaric oxygen therapy remains limited to uncontrolled series and a single small comparative study, with no randomized trials, so its efficacy is unproven. The overall mortality was 15.3%. In a proportion meta-analysis of primary cohorts, pooled estimates were: diabetes 82.4% (95% CI 68.2–91.1), Pseudomonas aeruginosa 55.6% (48.4–62.6), clinical cure 84.7% (74.6–91.2), cranial nerve involvement 28.0% (16.1–43.9), and mortality 8.4% (4.3–15.8). Conclusions: SBO remains a serious condition requiring multimodal diagnostic evaluation and prolonged antimicrobial therapy. Emerging fluoroquinolone resistance constitutes a pressing clinical challenge. Standardized diagnostic criteria, prospective multicenter trials, and consensus treatment protocols are urgently required.