Læknablaðið : fylgirit - 01.06.2005, Page 39

ABSTRACTS / XXIX CONGRESS OF THE NORDIC ASSOCIATION OF OTOLARYNGOLOGY
membrane. A conspicuous feature of endolymphatic hydrops
(and Méniére’s disease) is the presence of marked binaural dip-
lacusis. Diplacusis is the altered pitch perception of a fixed pure
tone presented alternatively in each ear. The normal value is
about 1-5%.
We measured Fowler’s test and diplacusis at 250 and 1000 Hz
using portable equipment and randomized maximum likelihood
sequential procedure. A normal hearing subject (woman, age
51) was first measured during 22 symptom-free days and was
considered having normal diplacusis, as stated above, on average,
though with a few uncharacteristic fluctuations. The same subject
developed endolymphatic hydrops with tinnitus, fluctuant low
frequency hearing loss and pressure in the affected ear 3 months
after this first test period. The subject was measured again during
14 days and now displayed diplacusis intermittently in the range
of -14% to 23%. In musical terms, this corresponds to more than
three semitones. Only the results of the 250 Hz test tone displayed
fluctuations in diplacusis which seem to agree well with previous
modelling of pressure effects on the cochlea.
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