For further evaluation of the seventh and eighth cranial nerves, high-resolution MR imaging was performed using the 3.0-T Achieva system (Philips Medical Systems, Best, The Netherlands). A reduced right vestibular response was found by a caloric test.Īxial and coronal reformatted HRCT images of the temporal bones were obtained. An examination with brain stem electric response audiometry (BERA) showed no response from the right ear. Pure tone audiometry and speech testing showed total deafness of the right side, but normal hearing thresholds in the left side. There was no evidence of syndromic deafness stigmas. The patient had never had mumps or head trauma. There was no family history of hereditary sensorineural hearing loss. ![]() No symptoms of ear fullness or pressure were reported. The child did not present any vestibular symptoms or tinnitus. The facial nerve function was unimpaired and symmetric. At the physical examination, the otologic status and head and neck status were normal. We report an unusual case of an isolated narrow IAC with duplication with a relatively wide anterosuperior portion containing an intact facial nerve and an inferoposterior empty stenotic portion as evaluated by MRI.Ī 6-year-old girl presented with unilateral hearing loss. To date, only five cases of narrow IAC with duplication have been reported in the literature ( 2, 5 - 8). However, technological advances in magnetic resonance (MR) imaging have made it possible to evaluate the fine neural structures along the course of the vestibulocochlear nerve of the IAC in patients with congenital sensorineural hearing loss. It has been thought that this anomaly is caused by aplasia or hypoplasia of the vestibulocochlear nerve that results in ipsilateral congenital sensorineural hearing loss ( 1, 2, 5).Īlthough HRCT is a common technique that is used to evaluate the inner ear and related structures in patients with hearing loss, it has only been able to demonstrate the presence of bony abnormalities in approximately 20% of patients with congenital sensorineural hearing loss ( 3, 4). This malformation comprises 12% of congenital temporal bone anomalies ( 3, 4). A narrow IAC can be diagnosed when the diameter of IAC is less than 2 mm as seen on high-resolution CT (HRCT) of the temporal bone ( 2). ![]() A narrow internal auditory canal (IAC) with duplication is a rare congenital disorder that is usually associated with other inner ear, middle or external ear abnormalities ( 1).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |