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

Current diagnostic methods for inner ear fluid disorders lack sensitivity for minor hydrops. Traditional audiometric tests fail to detect subtle changes in endolymphatic pressure. Established knowledge shows that labyrinthine hydrops involves abnormal fluid accumulation in the inner ear. No prior work had resolved how to distinguish minor from major hydrops using non-invasive methods. This gap motivated the search for a more sensitive clinical tool. Prior research has shown that positional impedenzometry can detect changes in middle ear function. However, its utility in diagnosing endolymphatic hydrops remains limited. This paper's contribution lies in exploring acetazolamide's role in enhancing positional impedenzometry's diagnostic accuracy.

The study aimed to assess whether acetazolamide improves the diagnostic accuracy of positional impedenzometry in detecting endolymphatic hydrops. Researchers sought to determine if acetazolamide administration alters middle ear impedance in patients with suspected hydrops. The specific problem addressed is the inability of standard tests to detect minor fluid imbalances in the inner ear. Motivation stems from the need for a more sensitive diagnostic approach. The authors proposed that acetazolamide could influence endolymphatic sac CO2 levels, affecting test results. They hypothesized that this method would outperform traditional audiometric tests. The study focused on comparing pre- and post-acetazolamide test results in patients versus controls. The goal was to establish a new diagnostic protocol for inner ear fluid disorders.

The study used a case/control design with 500 mg intravenous sodium acetazolamide. Participants were selected based on symptoms and clinical signs of endolymphatic hydrops. Tonal audiometry and positional impedenzometry were performed before and after drug administration. The Marullo method was used for positional impedenzometry measurements. Three test phases were conducted: pre-test, post-ACZ1, and post-ACZ2. Delta PISC values were calculated to assess impedance changes. Control subjects showed no significant changes in test results. The authors monitored threshold variations in audiometry to evaluate drug effects.

Audiometry showed a 77.2% significant threshold variation in cases after acetazolamide administration. Pre-test delta PISC averaged 22.06% in the study group. Post-ACZ1 reduced this to 13.16%, and post-ACZ2 increased it to 23.15%. These changes were not observed in control subjects. The largest effect occurred during the post-ACZ2 phase. The drug's influence on endolymphatic sac CO2 levels was proposed as a mechanism. The authors suggest that acetazolamide alters middle ear impedance in hydrops patients. These findings support the use of this method over classical tests for diagnosing Ménière's disease.

The authors state that acetazolamide-enhanced positional impedenzometry offers advantages over traditional tests. They propose that this method improves detection of minor and major hydrops. The test's sensitivity is attributed to acetazolamide's effect on endolymphatic sac CO2 levels. No prior work had resolved how to distinguish minor from major hydrops using non-invasive methods. The authors suggest that this approach may become a standard diagnostic tool. They caution that further validation is needed before widespread clinical adoption. The study highlights the potential of pharmacologically enhanced diagnostic techniques. The findings support the hypothesis that this method provides more accurate results than classical tests.