Clinical studies on the furosemide VOR test

Abstract

In order to detect vestibular endolymphatic hydrops, the directional preponderance of the VOR gain (VOR-DP%) during sinusoidal rotation (freq. 0.1Hz; Amp. 120deg) was calculated and compared between pre- and post-intravenous injections of furosemide (20mg). Abnormal changes in VOR-DP% (> = 10%) from the pre-injection level were referred to as positive in this furosemide VOR test (FVOR). The following results were obtained from this study. (1) Positive responses were obtained in 31 of 61 (51%) patients with definite Meniere's disease, in 11 of 21 (52%) patients with delayed endolymphatic hydrops and in 7 of 10 (70%) with syphilitic labyrinthitis. In contrast, the majority of patients responded negatively with sudden deafness or other peripheral vestibular disorders. (2) Following the endolymphatic shunt operation, in 2 out of 3 patients (67%) in whom vertiginous attacks had been decreased or disappeared after the operation results changed from positive to negative. (3) The positive rate in Meniere's disease was dependent on the frequency of the vertiginous attacks before the test or the duration from the last attack to the test. (4) Combined with the glycerol dehydration test or electrocochleography, the FVOR test could detect endolymphatic hydrops of Meniere's disease at a high positive rate. (5) There were no side-effects of the furosemide on the inner ear, such as deterioration of hearing acuity or tinnitus. In conclusion, the FVOR test is useful for detecting and following up fluctuating vestibular endolymphatic hydrops, which occur in disorders such as Meniere's disease, delayed endolymphatic hydrops and syphilitic labyrinthitis.