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WHAT IS MENIERE\'S DISEASE?
In 1861, a Frenchman named Prosper Meniere was the first to describe Meniere\'s disease accurately. Previously, people who had sudden attacks of dizziness were thought to be suffering from a kind of brain disturbance, but Meniere\'s work showed that there was something wrong with the inner ear.
Meniere\'s disease is more common in people of Northern European background than in Asian, Indian or black races. Approximately one person in every 2,500 of Australians with European lineage suffers from Meniere\'s disease. Recently Meniere\'s was genetically linked to the 6th chromosome in some cases.
The balance and hearing organs are found within the inner ear. The inner ear is composed of three semicircular canals and otolith organs which control balance and the snail-shaped cochlea which is the hearing organ. Within the cochlea there are two types of fluid. Endolymph, which is rich in potassium, and perilymph which is sodium-rich. The two fluids are separated by a strong, basilar membrane and a much thinner membrane known as Reissner\'s membrane.
In most cases with progressive Meniere\'s disease there is too much endolymph (endolymphatic hydrops) in the inner ear and many people can actually feel the fluid building up and the feeling of fullness it produces.
The ear is the most active part of the body, and the outer hair cells in the inner ear have the highest energy consumption of any part of the body. The endolymph surrounds the hair cells and is changed continuously every 20 minutes. The mechanisms which control the secretion of endolymph are unknown but are probably disordered in ears affected by endolymphatic hydrops.
The removal of the excess endolymph fluid takes place in two ways. Some is absorbed into blood vessels in the inner ear, and the remainder is drawn into the endolymphatic sac which then passes the fluid into the blood and lymphatic systems.
The flow of fluid is controlled by the secretion of an osmotic (water attracting) substance which is produced within the endolymphatic sac. In endolymphatic hydrops this mechanism eventually fails causing the accumulation of endolymph. It is the excess fluid which causes the symptoms of Meniere\'s disease. Sudden movement of this excess fluid is the most likely cause of the attacks of vertigo.
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GENERAL HEALTH
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