Background: Olfaction studies in the institution of Department of Otorhinolaryngology at Leicester Royal Infirmary have detected a previously unreported, variable phenomenon--'superosmia'--in which subjects' olfaction threshold concentrations are up to 100,000 smaller than the average value.
Objectives: The aim of this report is to define and quantify this phenomenon.
Methods: Two hundred and thirty subjects, who had been screened for active nasal pathology (age range 20-60 years), underwent individual olfactory threshold tests for phenylethyl alcohol or eucalyptol, using a computer-driven olfactometer in a controlled laboratory setting. Some tests were single tests and others were repeated on a small cohort.
Results: Two per cent of subjects demonstrated the superosmic phenomenon on single testing, and 10 per cent demonstrated this phenomenon on variable occasions during repeated testing. The superosmic phenomenon was defined by: (1) confident olfactory perception of a threshold at least equal to if not greater than three threshold levels below the subject's average threshold; (2) repeated perception of the odour at this level for at least 10 responses (1:1024 probability of chance finding); and (3) (where time permitted) a sudden, rapid loss of superosmia.
Conclusions: Superosmia is a distinct phenomenon, the stimulus or mechanism of which is currently the subject of further research. The enhancement of olfactory ability may be possible through activation of an accessory pathway or modulation of the existing olfactory apparatus.