A Case of Bilateral Profound Hearing loss Caused by Idiopathic Labyrinthitis that Showed a Clinical Course Similar to that of Delayed Endolymphatic Hydrops

A 66-year-old female presented with a history of sudden profound sensory neural hearing loss in her right ear from 61 yo and left fluctuating hearing loss from 64 yo. The clinical picture suggested a diagnosis “contralateral delayed endolymphatic hydrops.” However, 3T-MRI with tympanic administration of Gd showed no penetration of Gd into the inner ear on either side, and 3T-MRI with intravenous administration of Gd also showed no evidence of endolymphatic hydrops. Her left-side hearing gradually worsened to profound hearing resulting at 68 yo. When we performed cochlear implantation surgery for the profound hearing loss in her left ear, we found that the round window niche and basal turn of the membranous labyrinth were filled with granulation tissue, which was thought to be caused by some form of labyrinthitis. It is unusual, and noteworthy that this case of labyrinthitis initially showed a clinical course similar to that of delayed endolymphatic hydrops. In this paper, we would like to emphasize the necessity of excluding labyrinthitis in the differential diagnosis of hearing fluctuation fluctuating hearing loss and vestibular disorders, including delayed endolymphatic hydrops.