Objective: Cholesteatoma of the petrous bone extending into the intracranial region is an unusual occurrence. Most cases have been attributed to secondary extension of a primary epidermal blastomatous malformation of the temporal bone into the middle or posterior fossae. Within the past two and a half decades, intracranial extension of acquired aural cholesteatoma has been recognized as a likely alternative to this mechanism. Recent literature has rejoined this observation by considering both primary and secondary cholesteatoma of the petrous bone as a single group, petrosal cholesteatoma. The present study is presented to analyze the clinical presentation, imaging findings, and surgical treatment of six patients with acquired aural cholesteatoma extending into the intracranial region. Findings in this study are compared with the extant literature on congenital and acquired cholesteatoma of the petrous bone. This study proposes that petrosal cholesteatoma is a valid anatomical construct; however, the pathogenesis of petrosal cholesteatoma is still important in understanding the clinical presentation and management of cholesteatoma that extends beyond the usual confines of the middle ear and mastoid.
Study design: Retrospective case review conducted at a tertiary referral center.
Methods: From 1985 to 1999, 477 patients were surgically treated for acquired aural cholesteatoma. Patients with intracranial extension of cholesteatoma were studied. Clinical presentation, imaging studies, operative findings, surgical treatment, and postoperative results were evaluated.
Results: Six cases in a series of 477 patients with acquired aural cholesteatoma had intracranial extension of disease. In this series, the most frequent pathway for intracranial extension was supralabyrinthine through the supratubal recess into the middle cranial fossa. A less frequent pathway was via the retrofacial air cells into the posterior cranial fossa. Surgical access for removal of intracranial cholesteatoma was accomplished through several approaches including translabyrinthine, transcochlear, retrolabyrinthine, and middle cranial fossa. In two patients who had reoperation for possible residual disease, one was free of residual disease and one was found to have residual cholesteatoma in the region of the horizontal facial nerve.
Conclusion: Acquired aural cholesteatoma can extend into either the middle or posterior cranial fossae. In this study, cholesteatoma extended into the middle fossa through the supratubal recess along the labyrinthine facial nerve and into or above the internal auditory canal. A less frequent path is through the retrofacial air cells into the posterior fossa. Intracranial acquired cholesteatoma is generally small and presents with complaints related to underlying otitis media rather than the neurological deficits that are often associated with primary petrous bone cholesteatoma. While computed tomography and magnetic resonance imaging are both required to differentiate congenital petrous cholesteatoma from other lesions of the petrous bone, computed tomography of the temporal bone is usually sufficient to diagnosis and define intracranial extension of acquired aural cholesteatoma. These lesions can be completely excised rather than exteriorized.