Experimental pathogenesis of hydrops.

1. The best method for inducing hydrops in guinea pigs is obliteration of the endolymphatic duct. 2. The location of hydrops produced in the guinea pig is comparable to that of Menière's disease. 3. The major histopathological finding in the guinea pig is atrophy of sensorineural elements in the apical turns of the cochlea. 4. The vestibular sensory cell population is rarely decreased, though ultrastructural changes are noted. 5. Attempts to prevent or minimize development of hydrops by surgical fistulization of the vestibular endolymphatic walls or by administration of a diuretic drug, ethacrynic acid, failed in the guinea pig. Treatment of Menière's disease by these means is questionable. 6. Electron microscopy of the organ of Corti in cochleas taken from a patient with bilateral Menière's disease revealed that only a small percentage of te sensorineural elements was abnormal at the apical turns. Thus, it is questionable whether these small ultrastructural changes in the organ of Corti are a major cause of severe hearing loss. 7. In Menière's disease biochemical changes in cochlear fluid and/or changes in motion mechanics of the cochlear duct are probably important factors producing the hearing loss. 8. The present ultrastructural study did not resolve the question of the etiology of Menière's disease.