Gas-containing otogenic brain abscess.

Background: Gas-containing brain abscesses are very rare. Two mechanisms may be responsible for the presence of intracavitary gas: bacterial fermentation or penetration through an abnormal communication between the exterior and the intracranium. The need to search for this potential communication is considered an indication for open surgery. We report the case of a surgically treated gas-containing brain abscess originating from an undiagnosed chronic otitis media.

Case Description: A 54-year-old man developed acute neurologic deterioration, becoming comatose within 24 hours. A contrast-enhanced computed tomography (CT) scan disclosed a gas-containing cystic mass in the right temporal lobe. Urgent surgical decompression revealed the presence of an abscess, which was excised. During the same surgery, we performed a radical mastoidectomy, removing a previously undiagnosed attic cholesteatoma. Neither procedure revealed a discontinuity of the floor of the middle cranial fossa. Cultures grew a mixed flora. Antibiotics were administered for 6 weeks. The patient made a complete neurologic recovery.

Conclusion: This report demonstrates that otogenic brain abscesses may contain gas due to fermentation of nonclostridial bacteria.