[Effects of mannitol on the fluids of the internal ear. Use in the treatment of deafness].

The action of mannitol upon the inner ear fluids was studied experimentally by means of kinetics of mannitol entry into cochlear perilymph and endolymph in rats. A daily two hours infusion of 10% mannitol induces an osmotic water flow from cochlear fluids toward plasma. Following this therapeutic protocol, progressive, non-tumoral sensorineural hearing loss is enhanced in 32% of the cases. The rate of hearing improvement is larger than 50% in case of Ménière's disease. For sudden hearing loss, 75% of the cases are improved by mannitol, and 92% of the cases when the delay between the hearing loss onset and the mannitol therapy is less than two weeks. Sudden hearing loss should be considered as a sensory emergency.