 |
 |
The objective of our research is to find both the cause(s) of and a cure for Meniere's disease. The pathology (endolymphatic hydrops) and clinical symptoms (dizziness, tinnitus, and hearing loss) of this disease are well known; however, many treatments are not effective due to the disease's unknown etiology. Our approach is to develop an animal model with similar pathology for this disease and control the disease process using various experimental procedures. We have such an animal model in the guinea pig, which develops endolymphatic hydrops by ablation of the endolymphatic sac, an inner ear fluid-regulation site.
In some other species, however, the same procedure does not produce endolymphatic hydrops. We are in the process of determining morphometrical and enzyme activity differences in the endolymphatic sacs among these different species; this data will provide us with a clue to the etiology of endolymphatic hydrops. Malfunction of the endolymphatic sac will elevate calcium ions in endolymph, which may cause hearing loss. We inject calcium chloride into the animal's inner ear and determine whether it causes endolymphatic hydrops or damage to the hearing organ.
The clinical symptoms of Meniere's are thought to occur because of an increase in endolymphatic pressure, manifested by endolymphatic hydrops or a rupture of the distended membrane. The vestibular symptoms are normally lacking in the guinea pig model, but may be initiated by applying intermittent increased pressure with the aid of a hyperbaric pressure chamber. Another theory is that the symptoms have a vascular origin. Our recent finding in the gerbil indicates that the animals experience dizziness after interfering with blood drainage from the inner ear at the endolymphatic sac and their ears show vestibular sense organ damage.
We attempt to control endolymphatic hydrops by various methods. We will use a hormone-regulating drug to control over-secretion of endolymph from the strict vascularis and vestibular dark cells. A calcium antagonist will be used to control calcium ions and reduce endolymphatic hydrops. Patients afflicted with Meniere's disease are sensitive to atmospheric pressure changes. Hydropic animals will be placed in the hyperbaric chamber to decrease endolymph pressure in an attempt to control endolymphatic hydrops. We will provide a ventilation tube or make a hole in the tympanic membrane of the hydropic animal's ears to minimize endolymphatic pressure.
Kimura R.S., Trehey J.A., Hutta J. Degeneration of vestibular sensory cells caused by ablation of the vestibular aqueduct in the gerbil ear. Ann. Otol. Rhinol. Laryngol. 1994 (in press).
Robert S. Kimura, Ph.D.
For further information about work performed at the ENT Electron Microscopy Laboratory, call 617-573-3592 (voice).
 | We comply with the HONcode standard for
health trustworthy information: Verify here. |
|
|
|
