Experimental Study of Cochlear Blood Flow in Meniere's Disease

Abstract

Regarding the causes of endolymphatic hydrops in Meniere's disease, vascular dysfunction is considered to be one of them. In this present study, autopsy reports, experimental and clinical reports concerning the connection between vascular dysfunction and endolymphatic hydrops were reviewed.The measurement of Cochlear blood flow, which is considered to play an important role in vascular theory with the hydrops was not performed completely due to the anatomical restrictions and for this reason, many methods and devices were reported. For the purpose of knowing which method is best for measuring it, the methods which had been reported were reviewed.As the endolymphatic hydrops existed in scala media, it is important to know the blood flow in scala media in order to reveal the connection between vascular disorder and the hydrops. However, up until now, there was no report to measure it by using current method due to the anatomical restrictions. Therefore, the blood flow in the scala media was measured by using hydrogen clearance method, which was considered to be suitable to measure it, in normal guinea pigs and guinea pigs with hydrops. Guinea pigs with hydrops were produced experimentally by cauterizing the endolymphatic sac with 10% silver nitrate solution.Results are as follows;1) Vascular dysfunction was considered to be a cause of endolymphatic hydrops from the reviewed literatures. However, there are no reports to make endolymphatic hydrops by vascular occulusion experimentally. The reports in which vascular dysfunction were presumed to be produced due to the existence of endolymphatic hydrops were seen.2) Hydrogen clearance method is considered to be the best and only method currently for measuring blood flow in scala media from the reviewed literatures.3) In normal guinea pigs, the blood flow in scala media was 6.7±0.9ml/min/100g (n=14)4) In guinea pigs with hydrops, the blood flow in scala media was 5.5±0.7 ml/min/100g (n=10).5) From the statistical analysis, a significant decrease of blood flow in scala media was observed in guinea pigs with hydrops compared with normal ones. (p<0.001)6) It was suspected that the decrease of blood flow in scala media of guinea pigs with hydrops would be caused by atrophy with stria vascularis, from the histopathological findings.