Large Clinical Series Allows Description of Parosmia

Laurie Barclay, MD

February 24, 2005

Feb. 24, 2005 — A large series of patients, reported in the February issue of the Archives of Otolaryngology – Head & Neck Surgery, allows a description of parosmia.

"Parosmia is the perception of an unpleasant olfactory experience when an odorant is being presented," write Pierre Bonfils, MD, PhD, from the Université René Descartes in Paris, France, and colleagues. "Alterations in the pleasure of these chemosensory sensations have serious effects on the quality of life."

Using subjective olfactory symptom analysis and olfactory function test results, the investigators evaluated 56 consecutive patients who presented to the ORL Clinic, European Hospital Georges Pompidou, with a chief complaint of parosmia between October 2001 and November 2003.

In the 56 patients, the mean duration of parosmia was 63.0 months (range, three months to 22 years); 40 patients (71.4%) reported associated hyposmia, and 16 (28.6%) reported anosmia. All patients had moderate to severe olfactory loss on olfactory testing.

In 32 patients (57.1%), quantitative and qualitative alterations occurred simultaneously, whereas parosmia onset occurred within three months after quantitative dysosmia in 19 patients (33.9%) and after three months in five patients (8.9%).

The sensation of parosmia was always reported to be unpleasant, typically described as a foul, rotten, sewage, or burn smell. The main odorant triggers were gasoline in 30.4%, tobacco in 28.3%, coffee in 28.3%, perfumes in 21.7%, fruits in 15.2% (primarily citrus fruits and melon), and chocolate in 13.0%. Olfactory symptoms severely affected quality of life in 31 patients (55.4%).

Using a 10-cm visual analog scale, the mean severity of olfactory dysfunction was 7.5 ± 0.3, and the mean severity of flavor dysfunction was 6.4 ± 0.3. The patients described their flavor dysfunction as a perception of burned food, feces, or garbage. Upper respiratory tract infection was associated in 42.8% of the patients.

"The series of patients with parosmia presented herein, the largest in the literature, permits a clinical description of this rare olfactory abnormality," the authors write. "The cause of parosmia is not clear. Two main physiopathological hypotheses include a peripheral theory and a central theory."

The authors report no financial conflicts of interest.

Arch Otolaryngol Head Neck Surg. 2005;131:107-112

Reviewed by Gary D. Vogin, MD

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