Idiopathic phantosmia: outcome and clinical significance

Little is known about the clinical significance of phantosmia. The literature on phantosmia indicates that this symptom has a wide range of differential diagnoses. However, most cases of phantosmia remain of unknown origin. Our goal was to follow up patients with idiopathic phantosmia, with special regard to improvement rates and possible severe health conditions preceded by phantosmia of unknown origin.

Forty-four patients with idiopathic phantosmia which had consulted our Ear-Nose-Throat Smell and Taste Clinic over the last 10 years were contacted by telephone and underwent a structured medical interview.

None of the patients had developed any severe health condition or Parkinson's disease. More than 5 years after the occurrence of phantosmia, more than 50% of the patients experienced disappearance (31.8%) or improvement (25%). In the remaining cases, phantosmia did not change (38.7%) or became worse (<5%).

The main findings of the present study were that idiopathic phantosmia improves or disappears in almost two thirds of the patients after more than 5 years, and that idiopathic phantosmia seems to be more likely a harmless symptom rather than a reliable predictor of early Parkinson's disease or other severe diseases.