Internal auditory canal exostosis: A case report and review of literature

Abstract

Objective: Exostosis of the internal auditory canal (IAC) is a rarely reported entity. We present a case of unilateral IAC exostosis with longitudinal radiographic imaging and its associated abnormal neurodiagnostic and audiologic studies. To our knowledge, this is the first documented report of a patient with hyperostosis of the IAC who was radiologically followed for over a decade. Methods: One patient with unilateral IAC exostosis from the Michigan Ear Institute, a private tertiary referral center, is presented. Radiologic, neurodiagnostic, and audiologic modalities are reviewed with a discussion of the pertinent literature and current treatment options. Results: No change in radiologic findings or clinical symptoms in over a decade of follow-up. Abnormal audiograms, facial nerve electroneuronography, audio brainstem reflex, and videonystagmography were documented. Conclusions: Bony exostosis of the IAC is a rare condition and the natural history is still largely unknown. In this case, there was no progression of bony narrowing of the porus acousticus over a 12-year time period. This, in conjunction with stable symptomatology, has led us to recommend a trial of watchful waiting with conservative management. Future studies should be performed to monitor patients over time with serial imaging, audiograms, and neurodiagnostic testing to elucidate the natural history of this condition. Keywords: Internal auditory canal, Osteoma, Exostoses, Audiogram, Sensorineural hearing loss