Summary:Twelve patients with auditory and/or vestibular symptoms were examined with a gadolinium magnetic resonance imaging (Gd-MRI) study. They all were found to have enhancement of only the endolymphatic duct/sac structures of the inner ear. Most of these findings were unilateral, but a few were bilateral. The patients underwent auditory, vestibular, and blood tests in an attempt to clarify the reason for this abnormal enhancement. Several specific etiologies were identified, but several cases had unknown causes. In this article we review the concept of inflammation of the inner ear structures with particular attention to the role of the endolymphatic duct/sac in the immune response of the inner ear. The idea of an inflammatory response of the inner ear leading to endolymphatic hydrops (Meniere's disease) is discussed, but these patients did not follow a clear path from inflammation of the endolymphatic duct/sac to endolymphatic hydrops. However, the longest follow-up was only 4 years, and our observations remain preliminary. Finally, the authors have found that Gd-MRI study of the inner ear provides valuable information in the investigation of patients with new auditory and/or vestibular symptoms.