Ménière's disease Ménière's disease Ménière's disease (MD) is a disorder of the inner ear that is characterized by episodes of feeling like the world is spinning (vertigo), ringing in the ears (tinnitus), hearing loss, and a fullness in the ear. Typically only one ear is affected, at least initially; however, over time both ears may become involved. Episodes generally last from 20 minutes to a few hours. The time between episodes varies. Over time the hearing loss and ringing in the ears may become constant. The cause of Ménière's disease is unclear but likely involves both genetic and environmental factors. A number
Inner ear top of the head, and in some teleosts, it is simply blind-ending. In all other species, however, it ends in an endolymphatic sac. In many reptiles, fish, and amphibians this sac may reach considerable size. In amphibians the sacs from either side may fuse into a single structure, which often extends down the length of the body, parallel with the spinal canal. The primitive lampreys and hagfish, however, have a simpler system. The inner ear in these species consists of a single vestibular chamber, although in lampreys, this is associated with a series of sacs lined by cilia. Lampreys have