Introduction: True hyperosmia in a patient with phantosmia has not heretofore been described.
Case study: A 19-year-old right –handed female presented with a 4-month history of sudden onset of hallucinated smell and taste after swimming, when water infused her nostrils. The phantosmia was an unpleasant, fruity, rotten aroma which was always concurrent with the taste of rotten fruit. The phantom taste was 7/10 in intensity. The smell was always the same aroma but of variable intensity. It would occur every day up to three times a day, and usually 6-7/10 in intensity, and it would last from 1 hour to many hours. Since the onset of this, she found that some odorants when phantosmia is present have enhanced intensity, more than 150 % of normal, including kitchen aromas, bleach, and soap.
Results: Abnormalities in Chemosensory Testing: in the absence of phantosmia: Olfaction: Alcohol Sniff Test: 30 (normosmia). Suprathreshold Amyl Acetate Odor Intensity Testing: hyperosmia. Retronasal Olfactory Testing: Retronasal Smell Index: 3 (reduced). Gustatory Testing: Propylthiouracil Disc Taste Test: 8 (normogeusia). When phantosmia is present: Alcohol Sniff Test: 13 (hyposmia).
Discussion: Possibly the phantosmia changed her focus of attention to ambient aroma, enhancing her intensity perception and thus reducing her olfactory threshold; such attention reduced olfactory stimuli threshold has been seen in industrial workers exposed to solvents (Schwartz, 1989). Possibly the primary abnormality is hyperosmia: her olfactory sensitivity threshold may be so low that she detects odors in the environment that others don’t, which are interpreted as phantosmia and phantogeusia (due to reverse retronasal olfaction). This case highlights the need to test those who complains of phantogeusia and phantosmia for olfactory sensitivity, it also suggests treatment approaches for resistant phantosmia and phantogeusia including physical or pharmacological measures to reduce the underlying olfactory ability. Further studies in this arena are warranted.