[Positional impedance tests with acetazolamide: a clinical test for evaluating endolymphatic hydrops].

The authors report on the possible advantages acetazolamide, in conjunction with Positional Impedenzometry, can provide in the detection of minor labyrinthine hydrops and major labyrinthine fluid tension disorders. This study was carried out using the case/control method. The subjects were selected on the basis of symptoms and clinical examination revealing signs of endolymphatic hydrops. Tonal audiometry and positional impedenzometry according to Marullo were performed both before (pre-test) and after i.v. administration of 500 mg sodium acetazolamide (post-ACZ1 and post-ACZ2). Audiometry showed that in 77.2% of the cases there was a significant variation in threshold. In positional impedenzometry the average post-ACZ1 (delta PISC went from 22.06% (pre-test) to 13.16% and the post-ACZ2 (delta PISC went to 23.15%). On the other hand no significant changes were seen in the controls. Some hypotheses are offered on the mechanisms giving rise to these effects and particular attention is focused on the effect acetazolamide has on the carbon dioxide in the endolymphatic sac. In conclusion the authors consider the advantages this method offers over the "classical" tests used in diagnosing Ménière's Disease and minor hydrops.