In suspected malignant otitis externa, initial imaging to assess skull base involvement is indicated.

• A. Ultrasound of the temporal region.
• B. CT or MRI of the temporal bone to assess skull base involvement.
• C. Plain X-ray of the skull.
• D. No imaging is indicated.

Answer: (B)

When malignant otitis externa is suspected, the risk is that the infection may invade the skull base and temporal bone, so imaging to determine the extent of involvement is essential. High-resolution CT of the temporal bone is excellent for showing bony erosion and osteomyelitis at the skull base, which helps identify the spread early. MRI complements this by better delineating soft tissue spread and potential intracranial extension, including involvement of the dura, brain, or cranial nerves.

Ultrasound isn’t able to assess bone well and won’t reliably detect skull base osteomyelitis. Plain X-ray lacks sensitivity for early bone changes and is not helpful in this context. Therefore, the best initial approach to assess skull base involvement is imaging of the temporal bone with CT or MRI, choosing CT for rapid, detailed bone assessment and MRI when there’s concern for soft tissue or intracranial involvement.