Skull base osteomyelitis (SBO) is a rare and complex infection that includes malignant external otitis and central skull base osteomyelitis.

Symptoms are often non-specific, and the disease typically progresses slowly, leading to delays in diagnosis and treatment, as well as local or regional complications.

Management is not standardized and consists of medical treatment tailored to microbiological sampling results (antibiotic or antifungal therapy). Monitoring strategies and treatment modalities, particularly treatment duration, have not been standardized.

Given the rarity of these infections, it is currently very difficult to conduct prospective studies comparing different management approaches.

This will be a prospective multicenter study involving departments of Otorhinolaryngology (ENT), Infectious Diseases, Diabetology, and Internal Medicine.

Patients receiving care for skull base osteomyelitis who are seen either in outpatient consultation or during hospitalization will be included in the study, provided that their non-objection to participation has been obtained.

Patients will be managed and monitored according to standard clinical practice (routine care).

Inclusion Criteria:

• Participants must meet all of the following criteria:
• Age ≥ 18 years.
• Diagnosis of skull base osteomyelitis, based on the combination of:
• Clinical signs: otorrhea and/or otalgia and/or granulation tissue in the external -auditory canal, headache(s) and/or paralysis of one or more cranial nerves;
• AND radiological findings: bone destruction/osteolysis demonstrated on CT scan and/or MRI.

Exclusion Criteria:

• Participants meeting any of the following criteria will be excluded:

Expressed refusal (objection) to participate in the study. Individuals under legal protection measures (guardianship, curatorship, or judicial protection).

Patients managed for osteoradionecrosis. Patients managed for squamous cell carcinoma of the external auditory canal.

All patients aged 18 years or older diagnosed with skull base osteomyelitis (see definition below) during outpatient consultation or hospitalization at Lariboisière Hospital will be eligible for inclusion in the study, provided that they do not object to participation.