Unilateral Dilatation of Internal Auditory Canal; Report of Five Cases

Abstract

Five cases of unilateral dilatation of the internal auditory canal with positive neuro-otological findings are presented. Acoustic neurinoma was ruled out by MRI or CT.
The unilateral dilatation of the internal auditory canal was thought to due to so-called patulous canal in one patient and to neurofibromatosis in one. It appeared to be a normal variant in three patients. In patient with a patulous canal, there was ballooning of the internal ear canal. The causes of the ipsilateral positive neuro-otological findings were unknown.
Undoubtedly, temporal bone tomography and neuro-otological examinations play important roles in the diagnosis of acoustic neurinoma, but we should consider the possibility of misdiagnosis due to false positive results of these examinations. The final diagnosis of acoustic neurinoma must rely on MRI findings.