Table 1. Diagnostic criteria for otogenic skull base osteomyelitis.

Major signs (essential)

1. Nonacute, persistent, and severe pain (headache or otalgia)

2. Cortical bone destruction in the petrous portion of temporal bone and/or the clivus on HRCT

3. Low signal intensity of bone marrow in the petrous portion of temporal bone and/or the clivus on T1WI MRI

4. Exclusion of malignancy by tissue specimen   • External auditory canal cancer   • Nasopharyngeal cancer   • Metastasis

5. Exclusion of other inflammatory diseases by symptoms, otoscopic findings, blood exam, bacterial culture, CT, and MRI   • Acute infection (acute mastoiditis, petrous apicitis, retropharyngeal abscess)   • Cholesteatoma   • Cholesterol granuloma   • Tuberculosis   • OMAAV

Minor signs (adjunctive)

1. Immunocompromised status, including DM

2. Old age (65+ years)

3. Pseudomonas aeruginosa

4. No fever higher than 38°C

5. Refractory external otitis (exudate, edema, granulation)

6. Abnormal ESR or CRP

7. Cranial nerve dysfunction

8. Bone involvement on RI scanning (Tc-99m or Ga-67) or PET (high RI/PET uptake in the petrous portion of temporal bone and/or the clivus)

Abbreviations: CRP, C-reactive protein; CT, computed tomography; DM, diabetes mellitus; ESR, erythrocyte sedimentation rate; Ga, gallium; HRCT, high-resolution CT; OMAAV, otitis media with ANCA-associated vasculitis; PET, positron emission tomography; RI, radio isotope; T1WI, T1-weighted image; Tc, technetium.