Ménière's disease turn, is strongly associated with developing MD, but not everyone with EH develops MD: "The relationship between endolymphatic hydrops and Meniere's disease is not a simple, ideal correlation." Additionally, in fully developed MD the balance system (vestibular system) and the hearing system (cochlea) of the inner ear are affected, but there are cases where EH affects only one of the two systems strong enough to cause symptoms. The corresponding subtypes of MD are called "vestibular MD", showing symptoms of vertigo, and "cochlear MD", showing symptoms of hearing loss and tinnitus. The mechanism of MD is not fully explained by EH,
Middle ear of the bone known as the hyomandibula in fish ancestors, a bone that supported the skull and braincase. The structure of the middle ear in living amphibians varies considerably, and is often degenerate. In most frogs and toads, it is similar to that of reptiles, but in other amphibians, the middle ear cavity is often absent. In these cases, the stapes either is also missing or, in the absence of an eardrum, connects to the quadrate bone in the skull, although, it is presumed, it still has some ability to transmit vibrations to the inner ear. In many amphibians, there