Stenosis of the Internal AuditoryCanal with VIIth and VIIIth Cranial Nerve Dysfunctions

Abstract

We report the case of a 37-year-old woman with a history of long-standing right-sided sensorineural hearing loss who presented with an acute onset of vertigo and ipsilateral facial palsy. A computed tomographic scan study showed a stenosis of the right internal auditory canal (IAC). Neither generalized skeletal disease nor bony tumors, which may cause the IAC stenosis, were evident. The IAC stenosis found in this patient may be due to congenital malformation. Inflammation, compression or ischemia in the stenosed IAC may have resulted in the vertigo and facial palsy. This is the only case that we are aware of in which IAC stenosis is accompanied by vertigo and facial palsy.

Neuro-Otologic Findings in Unilateral Isolated Narrow Internal Auditory Meatus

“…The cochlea and the hypoplastic cochlear nerve might have been further damaged postnatally for certain reasons (e.g., a sudden decrease in cochlear blood supply caused by inflammation, edema and so on) because the cochlear artery is an end artery. In this relation, acquired facial palsy in a case of IAM stenosis was previously reported (15). Therefore, when this disorder is encountered, we suggest that the thorough neuro-otologic examination, preferably including inferior vestibular nerve evaluation, should be performed and that the patient should be followed up on a regular basis (e.g., once per 1-2 years).…”

“…Not many articles reported vestibular findings in narrow IAM (1,(14)(15)(16)(17)(18)(19). OHC function was poor or absent in all four ears in which otoacoustic emission responses were measured, caloric responses were present in three of the seven ears tested, and VEMPs were normally evoked in one ear tested.…”

Histopathologic investigation of the dimensions of the cochlear nerve canal in normal temporal bones

“…A similar condition, internal auditory canal stenosis, has been well correlated with sensorineural hearing loss in both unilateral and bilateral internal auditory canal stenosis cases [7][8][9][13][14][15][16]. During embryologic development, a layer of mesoderm surrounds the vestibulocochlear complex.…”

Narrow Duplicated or Triplicated Internal Auditory Canal (3 Cases and Review of Literature)

“…In a report by Curtin and May, 20 the labyrinthine segment of the facial nerve split into 2 thin filaments and the vestibulocochlear nerve was found to be atrophic. Sakina et al 21 and Nakamura et al 22 reported cases of IAC stenosis associated with ipsilateral facial nerve palsy, but none of them had separated IAC. Weissman et al 8 theorized that the early or abnormal division of the facioacoustic primordium can lead to an anomalous course of the facial and vestibulocochlear nerves.…”