Transmastoid approach to repair meningoencephalic herniation in the middle ear.

Meningoencephalic herniation (MEH) in the middle ear and mastoid is a rare pathological entity with possible life-threatening complications. We treated 24 patients with a trans-mastoid approach, and the bony defect was closed by heterologous materials positioned in a multilayer fashion. The cause of the bony defect were chronic otitis media with cholesteatoma, iatrogenic, spontaneous and post-traumatic. The major presenting symptoms were meningitis, headache, conductive hearing loss, cerebrospinal fluid (CSF leak), neurologic deficit and pneumoencephalus, and stenosis of a canal wall down cavity. During follow-up, no patient developed complications due to surgery or related to the pathology, and imaging showed a stable occlusion of the bony defect. Different surgical treatments have been proposed to repair MEH, and the choice is based on the localization and size of the bony defect, preoperative auditory function and the presence of a coexisting pathology. We propose the use of collagenous membranes and bone substitutes for reconstruction of the floor of the middle fossa.