Recent advances in Meniere's disease research in the United States.

The recent advances in Meniere's disease research in the United States have been on all fronts, in understanding the pathology and pathologic physiology of Meniere's disease, the natural history of the disease, and in testing to verify the presence of endolymphatic hydrops, and in various forms of medical and surgical treatment.The electrocochleography, using the acetazolamide hyaration and glycerol dehydration tests, has added greatly to our understanding of Meniere's disease.The continued investigation of the vestibular aqueduct by hypocycloidal polytome and in the future with CAT scanning has increased our understanding of the cause of idiopathic endolymphatic hydrops and the likelihood of benefit from operations on the endolymphatic sac.The observation that ears with Meniere's disease have an angle of less than 70 degrees between the vestibular aqueduct and the posterior semicircular canal as compared to normals in which the angle is always greater than 70 degrees will be, if true, very helpful in quantifying the diagnosis of Meniere's disease.Continued interest in early operations on the endolymphatic sac should increase information about the value of this procedure. Clearly the treatment for Meniere's disease must recognize it for what it is, an insidious, usually progressive but extremily variable disorder of the inner ear. Without question the funda-mental cause is developmental, a small, misplaced Early in life the regulation of fluid balance in the sac. inner ear begins to be compromised but there is enough excess capacity in the system to compensate for the small inadequate sac. The Dynamic Flow Theory of Lundquist (Figure 26) best explains the probable sites of production and absorption of endolymph and the roles of the stria vascularis and the endolymphatic sac. At this point there may be an insult to the system, to the stria vascularis and/or the endolymphatic sac, to disturb this already compromised equilibrium. This insult may be chemical, as by overloading the body with sodium and hence we believe the real but as yet unproven value of salt restriction and potassium-sparing diuretics in the management, not cure, of Meniere's disease in the early, still fluctuating stage. This insult may be metabolic, from disorders of glucose and/or lipid metabo lism, hence the very real obvious value of correcting these disorders when present. This insult may be autoim mune, the exact trigger for which remains to be found, hence the large number of patients with Meniere's disease with positive tests of autoimmunity to purified collagen likely to be present in the inner ear and the remarkable response in some patients to large doses of steroids. The insult may be other as yet unproven wtimuli shich remain to be found.Once this insult to the system takes place, the already compromised equilibrium is overwhelmed, the disease enters the uncompensated phase and hydrops of the cochlear and/or vestibular labyrinth occurs, and corresponding signs and symptoms appear. Most patients are first seen by the doctor after the system is compromised and treatment must be consistent with the situation which exists. That is why we have attempted to make the diagnosis early, before the system is compromised, and do the subarachnoid endolymphatic shunt early, which seems to us the most reasonable thing to be considering all the circumstances existent at that time.