Visualization of a high protein concentration in the cochlea of a patient with a large endolymphatic duct and sac, using three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging

Abstract

To evaluate the inner ear of a patient with an enlarged vestibular aqueduct and acute hearing deterioration, using three-dimensional fluid-attenuated inversion recovery (3D FLAIR) magnetic resonance imaging (MRI). Three-dimensional fluid-attenuated inversion recovery MRI has been recently developed to detect haemorrhage and high concentrations of protein. Application of this method to inner-ear diseases has not been fully described. We used 3D FLAIR MRI to evaluate a patient with an enlarged vestibular aqueduct and acute hearing deterioration. On 3D FLAIR MRI, this patient had high signals in the endolymphatic duct and sac, the vestibule and the cochlea and was diagnosed as having a high protein concentration in the inner ear. These high signal areas were not detected by T1- and T2-weighted MRI. This is the first published case in which a high protein concentration in the cochlea of a patient with an enlarged vestibular aqueduct was detected by 3D FLAIR MRI. These findings strongly supported the theory of the pathophysiology of hearing deterioration in patients with an enlarged vestibular aqueduct, which states that hyperosmolar fluid in the enlarged endolymphatic sac refluxes into the cochlea, resulting in damage to the hair cells. Thus, these finding may help clarify the cause of hearing deterioration in the presence of a large endolymphatic duct and sac.