Cochlear Implantation ; Cochlear Implants ; Humans ; Vestibulocochlear Nerve Diseases

OBJECTIVE: To summarize the high-resolution computed tomography (HRCT) and magnetic resonance imaging (HRMRI) features of duplicated internal auditory canals (DIACs). MATERIALS AND METHODS: Ear HRCT data of 64813 patients with sensorineural hearing loss (SNHL), obtained between August 2009 and November 2017, were reviewed. Among these patients, 12 (13 ears) were found to have DIACs, 9 of whom underwent HRMRI. Their images were evaluated by two otoradiologists. RESULTS: The rate of occurrence of DIAC among SNHL patients was 0.019% (12/64813). The internal auditory canals of 13 ears were divided into double canals by complete (n = 6) and incomplete (n = 7) bony septa, with varied orientations ranging from horizontal to approximately vertical. All of the anterosuperior canals extended into the facial nerve (FN) canal, except for 1, which also extended to the vestibule. The posteroinferior canals ended in the cochlea and vestibule, except for 2, which also connected to the FN canals. Magnetic resonance images revealed that 77.8% (7/9) and 22.2% (2/9) of vestibulocochlear nerves (VCNs) were aplastic and hypoplastic, respectively. Furthermore, 88.9% (8/9) of FNs were normal, except for 1, which was hypoplastic. All of the affected ears also had other ear anomalies: a narrow, bony cochlear nerve canal was the most common other anomaly, accounting for 92.3% (12/13). Malformations of other systems were not found. CONCLUSION: Double-canal appearance is a characteristic finding of DIAC on HRCT, and it is usually accompanied by other ear anomalies. The VCN usually appears aplastic, with a normal FN, on HRMRI.
Cochlea ; Cochlear Nerve ; Ear ; Facial Nerve ; Hearing Loss, Sensorineural ; Humans ; Magnetic Resonance Imaging ; Vestibulocochlear Nerve

Peripheral vestibular disorder (PVD) is serious and common. Clinically, giving an accurate diagnosis of PVD can be challenging. Vestibular evoked myogenic potential (VEMP) is an objective test to evaluate the integrity of vestibular organs, particularly saccule and/or inferior vestibular nerve. This study was performed to determine the sensitivity and specificity of VEMP using different stimuli. Fourty normal and 65 PVD subjects who fulfilled the inclusion criteria were recruited. While sitting comfortably, VEMP waveforms were recorded with active electrode on sternocleidomastoid muscle and negative electrode on upper forehead. Tone bursts (500, 750 and 1000 Hz) were delivered via headphones at 90 dBnHL and 5/s presentation rate. VEMP parameters for each stimulus (amplitude and latency of P1 and N1 peak) were analyzed accordingly. Receiver operating characteristic (ROC) was performed to determine the sensitivity and specificity of VEMP at different test frequencies. N1 amplitude of 750 Hz stimulus produced the most ideal sensitivity (65% on right and 63% on left) and specificity (83% on right and 78% on left). The importance of using a few tone bursts in VEMP test in order to minimize the false negative in cases might be encountered in clinics as the certain tone burst had inadequate sensitivity in detecting PVD cases. The 750 Hz stimulus produced the most ideal VEMP with adequate values of sensitivity and specificity, at least in this study.
Vestibulocochlear Nerve Diseases

Objective: To present 3 cases of Möbius sequence exposed in utero to misoprostol and discuss their clinical presentations, etiopathogenesis, and management. Methods: Medical records of 3 patients with Möbius sequence and prenatal exposure to misoprostol were reviewed. Clinical findings were compared with those reported in the literature. Results: Lack of facial-muscle movement, lagophthalmos with secondary exposure keratitis, decreased ability to crease forehead, and shallow nasolabial fold imply facial-nerve dysfunction. Small- and large-angle esotropia and apparent orthotropia with abduction limitation showed varying degrees of abducens nerve involvement. Two patients had early prenatal exposure to misoprostol during the first 3 months of gestation. Conclusion A history of misoprostol exposure should be routinely elicited from parents of children with Möbius sequence. Associated deficiencies in Möbius sequence and its variants require a multidisciplinary approach.
Abducens Nerve Vestibulocochlear Nerve Paralysis

PURPOSE: The purpose of this study is to evaluate the significance of the hypoplastic canal for the cochlear nerve in patients with sensorineural hearing loss (SNHL) and the relationship between the hypoplastic bony canal and aplasia or hypoplasia of the cochlear nerve. MATERIALS AND METHODS: A retrospective review of high resolution temporal CT(HRCT) and MRI findings was conducted. The narrow bony canal of the cochlear nerve and the relative size of the internal auditory canal were correlated with the cochlear nerve deficiency on MRI. The comparative size of the component nerves (facial, cochlear, superior vestibular, inferior vestibular nerve), and the relative size of the internal auditory canal and the bony canal of the cochlear nerve were measured. The clinical history and the results of the clinical examination were reviewed for each patient. RESULTS: High resolution MRI showed aplasia of the common vestibulocochlear nerve in one patient and a deficiency of the cochlear nerve in 9 patients. These abnormalities occurred in association with a prominent narrowing of the canal for the cochlear nerve and a stenosis of the internal auditory canal, which was observed on temporal bone CT in 9 patients with congenital SNHL. Three patients had normal IAC, despite the presence of a hypoplastic cochlear nerve on the side on which they had SNHL. In one patient, the narrowing of the canal for the cochlear nerve and internal auditory canal were not found to be associated with acquired SNHL. CONCLUSION: The hypoplastic bony canal for the cochlear nerve might be more highly indicative of congenital cochlear nerve deficiency than that of the narrow internal auditory canal, and the position of the crista falciformis should also be carefully.
Cochlear Nerve* ; Constriction, Pathologic ; Hearing Loss, Sensorineural* ; Humans ; Magnetic Resonance Imaging* ; Retrospective Studies ; Temporal Bone ; Vestibulocochlear Nerve

BACKGROUND AND OBJECTIVES: Sensorineural hearing loss (SNHL) could be caused by dysfunction of the cochlea, abnormality of vestibulocochlear nerve (VCN), or disorder of central auditory pathway. Among these causes, VCN deficiency is one of the causes of profound sensorineural hearing loss. The aim for this study was to evaluate radiologic characteristics of VCN deficiency by reviewing temporal bone computed tomography (TBCT) and magnetic resonance image (MRI) findings of patients with profound unilateral SNHL, diagnosed as VCN deficiency and also, we compared the width of the bony canal of the cochlear nerve (BCCN) between the normal and affected side on TBCT and tried to clarify the diagnositc value of BCCN. MATERIALS AND METHOD: We reviewed TBCT and temporal submillimetric axial and parasagittal 3D turbo spin echo (3D-TSE) T2-weighted MRI of 9 patients who were diagnosed as unilateral VCN deficiency. We evaluated MRI findings in terms of the presence and comparative size of the component nerves (facial, cochlear, superior vestibular, inferior vestibular nerve) then we classified the type of VCN deficiency, according to the Casselman's proposal. We compared the difference of width of IAC and BCCN between normal and affected side on TBCT. RESULTS: We could find the detail anatomic feature of VCN in IAC by parasagittal MRI and could classify the type of VCN deficiency of patients, based on the Casselman's classification. According to the result of the classification, 8 patients were type 2A and the other one was type 1. In the TBCT study, the size of IAC and BCCN of the affected 8 ears were smaller than that of side and one patient had normal IAC but narrow BCCN of the affected ear. CONCLUSION: In this study, we conclude that TBCT and MRI could be useful methods for diagnosis of VCN deficiency. Also, the hypoplastic bony canal of the cochlear nerve on TBCT is finding to overlook easily and may be another important indicator for evaluating VCN deficiency.
Auditory Pathways ; Classification ; Cochlea ; Cochlear Nerve ; Diagnosis ; Ear ; Hearing Loss, Sensorineural ; Humans ; Magnetic Resonance Imaging* ; Temporal Bone ; Vestibulocochlear Nerve*

Neurovascular compression syndrome of the eighth cranial nerve is characterized by recurrent audiologic and vestibular symptoms. The clinical presentation is the most important for diagnosing neurovascular compression syndrome of the eighth cranial nerve. This review describes the pathophysiology, diagnosis and treatment of neurovascular compression syndrome of the eighth cranial nerve.
Diagnosis ; Nerve Compression Syndromes ; Vertigo ; Vestibulocochlear Nerve*

Vestibular paroxysmia is the name given to the syndrome caused by vascular compression of the vestibulocochlear nerve. The main symptoms of vestibular paroxysmia are recurrent, spontaneous, brief attacks of spinning, non-spinning vertigo or positional vertigo that generally last less than one minute, with or without ear symptoms (tinnitus and hypoacusis). Prior to attributing a patient's symptoms to vestibular paroxysmia, however, clinicians must exclude common conditions like benign paroxysmal positional vertigo, Menière's disease, vestibular neuritis and vestibular migraine. This is usually possible with a thorough history and bedside vestibular/ocular motor examination. Herein, we describe a patient with vestibular paroxysmia that mimicked resolved BPPV with a literature review.
Benign Paroxysmal Positional Vertigo ; Carbamazepine ; Ear ; Humans ; Migraine Disorders ; Neuritis ; Vertigo ; Vestibular Diseases ; Vestibulocochlear Nerve

Child ; Cochlear Implantation ; Cochlear Implants ; Evoked Potentials, Auditory, Brain Stem ; Hearing Loss, Central ; physiopathology ; Humans ; Vestibulocochlear Nerve Diseases ; physiopathology

The neurovascular cross-compression (NVCC) of the eighth cranial nerve (CN) is a clinical entity with symptoms of recurrent vertigo or tinnitus. Although the diagnostic criteria have been defined, the precise clinical presentation and pathomechanism have not been clarified. The treatment response to the carbamazepine; drug of choice for first line medical treatment, has been considered as one of the diagnostic criteria. Herein, we present a case of chronic uncompensated unilateral vestibular hypofunction who responded dramatically to carbamazepine medication. A 55 year-old male admitted to the hospital with symptoms of recurrent oscillopsia and headache for more than 7 years. His symptoms were aggravated by positional changes. Vestibular function tests showed spontaneous nystagmus, canal paresis on caloric test and vestibular dysfunction on dynamic posturography, which represented unilateral uncompensated vestibular hypofunction. Although his symptom was not relived by vestibular rehabilitation, he was treated with carbamazepine. A long standing uncompensated unilateral vestibular hypofunction without any auditory symptoms could be one of the clinical presentations in NVCC of the eighth CN.
Caloric Tests ; Carbamazepine ; Headache ; Humans ; Male ; Nerve Compression Syndromes ; Paresis ; Tinnitus ; Vertigo ; Vestibular Function Tests ; Vestibular Neuronitis ; Vestibulocochlear Nerve