The effect of bony cochlear nerve canal (BCNC) diameter on the degree of sensorineural hearing loss.

PURPOSE: This study investigated the correlation between the diameter of the bony cochlear nerve canal (BCNC), as determined by Temporal bone CT, and MRI findings of cochlear nerves (CN) in children with sensorineural hearing loss (SNHL). MATERIALS AND METHODS: A prospective study design was followed. Radiological data (Temporal bone CT and MRI) of fifty children with sensorineural hearing loss (age <18 y) were included in the study. All patients (100 ears) underwent routine MRI protocol in addition to 3D CISS (3-D constructive interference in steady state). RESULTS: Based on CT findings, the BCNC was classified according to its diameter into three groups; group 1 (<1.4 mm), group 2 (1.4-2.0 mm), and group 3 (>2.0 mm). A significant difference between the three groups at degrees of SNHL (p < 0.001) was observed. Significant difference (p < 0.001) was also observed in the mean level of pure tone audiometry (PTA) average in group 1 compared to group 2. The CN was absent in 20 ears of group 1 CT results (29%), CN hypoplasia was noticed in 40 ears of group 1 CT (58%). However, CN was present in 9 ears of group 1 CT (13%), while in group 2 and 3, CN was present in 100% of the cases (27, and 4 ears, respectively, p < 0.001). CONCLUSIONS: MRI and CT imaging are valuable in the diagnosis of SNHL in children. Moreover, with BCNC stenosis, there was a high probability of CN aplasia or hypoplasia.

Evaluation of the radiological criteria to diagnose large vestibular aqueduct syndrome.

OBJECTIVE: The main objective of the current work is to increase the sensitivity of the radiological diagnosis of the large vestibular aqueduct syndrome (LVAS). The specific aims were to compare between the two famous criteria to diagnose large vestibular aqueduct (LVA), (i.e., Valvassori and Cincinnati), to correlate between vestibular aqueduct (VA) measurements in the axial view and those in 45° oblique reformate in children with LVAS, and to define radiological criteria to diagnose LVA in the 45° oblique reformate. METHODS: The study group included 61 children with LVAS according to Cincinnati criteria (greater than 0.9mm at the midpoint or greater than 1.9mm at the operculum in the axial view). All participants were subjected to full Audiological evaluation and CT scanning in axial plane. The axial data were then transferred to workstation for post-processing with 3D reformatting software (Baxara 3D) in order to obtain the 45° oblique reformates. VA measurements were done at 4 points: midpoint and operculum in both the axial plane and the 45° oblique reformate. RESULTS: Only 81% of ears of children with LVAS (99 ears) fit Valvassori criterion (i.e., larger than 1.5mm at midpoint), while 19% (23 ears) of them were missed. There were statistically significant correlations among the diameters of the VA in the axial view (both in the midpoint and operculum) and their counterparts in the 45° oblique reformate. Values equal to or greater than 1.2mm in the midpoint and 1.3mm in the operculum are proposed to be the criteria to diagnose LVA in the 45° oblique reformate. Finally, no significant correlations were found between the degree of hearing loss and VA diameters at the axial or 45° oblique reformate. CONCLUSION: Cincinnati criteria are more sensitive than Valvassori criterin in the diagnosis of LVAS. We recommend the application of Cincinnati criteria instead of Valvassori criteria in order not miss cases with LVAS. Measurement of VA in the 45° oblique reformate is a reliable method to diagnose LVA. Criteria to diagnose LVA in the 45° oblique reformate were proposed.