Case Series Analysis of Skull Base Osteomyelitis at a University Hospital of Reference

Skull base osteomyelitis (SBO) is a rare and potentially severe infection that is difficult to diagnose due to its nonspecific clinical presentation. Early recognition and treatment are essential for prognosis. We describe five cases of SBO managed by the infectious diseases service of a tertiary university hospital between 2022 and 2025. Data were obtained from electronic medical record review. Mean patient age was 72.2 years (range 65–79), and 80% were male. Four patients (80%) had diabetes mellitus, and one (20%) was immunosuppressed after kidney transplantation. All patients began with otologic infections and progressed to neurological symptoms (four cases with cranial nerve palsies and one with altered mental status). SBO diagnosis was confirmed by CT (3 cases – 60%), MRI (1 case – 20%) and scintigraphy (1 case – 20%). Etiologic agents were identified through cultures of nasopharyngeal biopsy (40%), external auditory canal granuloma (20%), subcutaneous collection (20%) and otorrhea (20%). Pseudomonas aeruginosa was identified in 3 cases (60%), and 1 case had polymicrobial culture (20%). Deep cerebral venous thrombosis occurred in 2 cases (40%). Antibiotics covering P. aeruginosa and S. aureus were used in all cases, and 80% were later stepped down to oral regimens. Treatment duration ranged from 12 to 36 weeks, according to clinical course. Two patients were still receiving antimicrobials at the time of reporting, and two died (40%). Our series confirms findings from other reports that SBO occurs mainly in elderly, diabetic and immunocompromised patients. Otogenic infection is the main portal of entry, and cranial nerve palsies in this context should raise suspicion for SBO. Diagnosis is confirmed by imaging and requires culture of biopsy specimens to guide appropriate antimicrobial therapy. SBO is often diagnosed late and is associated with major uncertainty regarding management, antibiotic duration and limitations to surgical interventions. Given the high morbidity and mortality of SBO, it must be considered in the differential diagnosis of complicated otologic infections, especially when associated with neurological symptoms.