[Dilation of the internal auditory canal and intracanalicular vestibular schwannoma: what are the mechanisms involved?].

OBJECTIVES

To present a unique case of unilateral widening of the internal auditory canal (IAC) with no significant contact with an ipsilateral intracanalicular vestibular schwannoma (VS), raising the issue of the cause(s) of this IAC widening.

METHODS

The medical record and radiologic data were reviewed of a patient presenting an enlarged unilateral IAC, which led to the diagnosis of an intracanalicular VS that could not account for the dilation.

RESULTS

The patient had a unilateral dilation of the IAC that did not match the ipsilateral VS he had. As a result, this case motivated discussion of whether such dilation of the IAC was congenitally asymmetrical or the result of the mechanisms involved in the widening of the IAC.

CONCLUSIONS

Although asymmetry of IAC is a current notion, this case demonstrates a contrario that increased pressure exerted on the walls of the IAC cannot be the only mechanism in such widening.