Skull Base Osteomyelitis
Skull base osteomyelitis (SBO) is an infection of the bone or bone marrow, typically caused by bacteria or sometimes fungus. There are variety of names for this condition, including necrotizing external otitis, and malignant otitis externa. The infection causes damage in the region around the ear and skull base. SBO can be secondary to severe otitis externa (swimmers ear, also associated with exostosis), meaning that the infection begins in the lining of the ear canal and then progresses to the petrous apex. Fractures and trauma can also be a gateway for infectious bacteria to enter the bone or bone marrow.
SBO is relatively rare, and typically occurs in patients with an immune deficiency. Pain around the ear or eye, is an early symptom of SBO. Other symptoms include conductive hearing loss resulting from Eustachian tube dysfunction, sensorineural hearing loss secondary to inflammatory invasion of the cochleovestibular nerve, and a draining ear. Tinnitus and vertigo can also occur concurrently or independent of the hearing loss. Untreated SBO can cause facial paralysis due to inflammation around and compression of the facial nerve which runs through the temporal bone of the petrous apex.
Evaluation of SBO requires sophisticated audiologic testing and medical imaging. Identification of the cause of the infection, powerful antimicrobial medications, and occasionally surgery are employed in the treatment of SBO.