Brain Herniation into the Mastoid in a Normal Hearing Ear

Abstract

A cluster of right temporal lobe abscesses in a 40-year-old male originated from an endaural brain hernia affecting the mastoid only, without direct contact with the ossicular chain. In infancy, antrotomy had been performed. Otologic signs were sparse, hearing was normal. Computed tomography of the temporal bone showed homogenous clouding of the retro tympanal spaces and a defect of the tegmen antri. Treatment consisted of transmastoid débridement, reduction and duraplasty with fascia lata.

Imaging of temporal bone brain hernias: atypical appearances on magnetic resonanance imaging

“…While the bony defect may be well demonstrated on axial and direct coronal CT with data reconstructed using a bone algorithm, distinguishing between brain, cholesteatoma or granulation tissue on CT is difficult. This is due to their similar density values compounded by beam hardening effects of the temporal bone, limiting the ability to resolve subtle distinctions before and after contrast enhancement .17 , 19−21 The normally thin tegmen can be visualized using thin coronal CT slices, which intersect it at right angles. Sagittal or coronal image reformations from axial image data often provide useful information in the skull base but may not reliably resolve such thin bone in all cases.…”