Congenital malformations of the inner ear and the vestibulocochlear nerve in children with sensorineural hearing loss: Evaluation with CT and MRI

Purpose: The purpose of this work was to study the diagnostic value of CT a nd MRI in children with sensorineural hearing loss and to analyze anatomic abnormalities of the inner ear and the vestibulocochlear nerve in this pati ent group. Method: We evaluated 42 inner ears in 21 children with congenital deafness who had congenital inner ear malformations and who were candidates for coch lear implants. All patients were studied with high resolution MR and helica l CT examinations. The MR study included a T2-weighted 3D fast SE sequence. We describe and tabulate the anatomic abnormalities. Special attention was given to abnormalities of the vestibulocochlear nerve. The field of view i n the plane according to the length axis of the internal auditory canal (IA C) was 4 cm. Additional continuous parasagittal reformations perpendicular to the length axis of the IAC were studied with a field of view of 3 cm. Results: CT and MRI allowed accurate identification of malformations of the inner ear in children with congenital deafness. We identified 99 malformat ions, with a majority of patients demonstrating multiple abnormalities. Com mon imaging findings were Mondini abnormality and Mondini variants (12/42) and fusion of the lateral or superior semicircular canal with the vestibule (12/42). MRI demonstrated in 9 of 21 patients a rudimentary or absent vest ibulocochlear nerve in the auditory canal. Conclusion: CT and MRI are important modalities to analyze the inner ear in children who are candidates for cochlear implants. MRI with an extremely s mall field of view should be used to study possible abnormalities of the ve stibulocochlear nerves. This may alter clinical care and allow cochlear imp lant placement in patients whose electrodiagnostic studies suggest that the implant should not be performed. The detailed analysis of abnormalities of the inner ear might establish prognostic factors.