OSMOTIC DRUGS IN THE TREATMENT OF COCHLEAR DISORDERS - A CLINICAL ANDEXPERIMENTAL-STUDY

On the grounds of positive results obtained with Meniere's patients, a gents such as glycerol and mannitol have been included in the therapeu tical protocol of other cochlear disorders presenting with hearing los s either of sudden onset, but not observed at an early stage, or accom panied by tinnitus and aural pressure. Intravenous infusions of either 10% glycerol or 18% mannitol were given to selected patients 3 to 6 t imes with a time interval of 1 to 3 days. Hearing loss, tinnitus and a ural pressure were evaluated as improved, unchanged or worsened. In 33 % of the glycerol group and 23.8% of the mannitol group we observed he aring threshold improvement, while aural fullness improved in 45% of t he glycerol and 56.2% of the mannitol groups, and tinnitus was only re lieved in 13.1% of the glycerol and 5.8% of the mannitol group. A para llel experimental study was carried out on guinea-pigs in order to she d light on the effects of mannitol and glycerol on the inner ear. Coch lear blood how was measured with a laser Doppler flowmeter al the leve l of the basal turn of the cochlear lateral wall, both in normal and h ydropic guinea-pigs, before and after osmotic intraperitoneal infusion . Basal values in the normal cochlea were much higher than in the hydr opic one, and both mannitol and glycerol markedly influenced the local blood how in the normal cochlea, giving few or no changes in the hydr opic one.