Malignant external otitis with optic neuritis.

Malignant external otitis (MEO) is a progressive necrotizing infection which spreads to the skull base. The causative organism is usually Pseudomonas aeruginosa and 90% of the patients are diabetic. The infection gains access to the skull base at the temporal bone. Cranial nerve involvement is common. We present a case of malignant external otitis causing blindness due to optic neuritis. Progressive vascular involvement along the skull base is the pathogenic mechanism that best explains spread from the temporal bone to the orbital apex.