A study on the prognostic significance of qualitative olfactory dysfunction

Abstract

We investigated the frequency and prognostic significance of qualitative olfactory dysfunction (parosmia, phantosmia) in a retrospective patient based study. A total of 392 patients with impairment of olfaction were tested at least two times for their olfactory function using the "Sniffin' Sticks". The mean interval between the first and the last test was 11 months. At the first visit 34% of all patients reported parosmia. Parosmia was most frequent in patients with postinfectious olfactory loss (56%), and less frequent in idiopathic, posttraumatic, sinunasal disease with frequencies of 10, 14, and 28%, respectively. In contrast, only 12% of all patients had phantosmias, with no significant differences between the patient groups. Improvement of olfactory function was found in 23% of all patients (n = 90). Pre-existing parosmia or phantosmia had no significant effect on recovery rate. Regarding qualitative olfactory dysfunction, 29% of those patients reporting parosmia reported relief of this symptom after an average of 12 months, whereas 53% of phantosmic patients lost phantosmia during the observation period. Although it has been suggested that olfactory distortion s could be regarded as an indicator of early recovery of decreased olfactory sensitivity, the current data indicate that occurrence of parosmia or phantosmia has little prognostic value. Phantosmia disappears at a faster rate than parosmia. These insights into qualitative olfactory dysfunction are regarded to be significant in the counseling of patients with olfactory loss.

Idiopathic Phantosmia: Outcome and Clinical Significance

“…Unfortunately, these authors did neither differentiate between parosmia and phantosmia nor did they specify after what time lapse recovery occurred. Reden et al [1] reported parosmia to disappear or weaken in 29% and phantosmia in 53% of followed-up patients after an observational period of almost 1 year. This is similar to our rate after a mean observation of 6 years, which suggests that most phantom smells disappear within the first year, and very little supplementary recovery can be expected after this period.…”

“…Besides the pioneering work of Leopold and colleagues [2,13,14] who attempted to systematically describe, diagnose and treat phantosmia, little clinically useful knowledge is available to the otorhinolaryngologist. Recently, Reden et al [1] identified phantosmia to potentially occur in almost all conditions affecting the sense of smell. Amongst investigated cases, idiopathic phantosmia was the most frequent diagnosis.…”

“…The clinical knowledge of qualitative olfactory disorders is a little different. Systematic investigation of when and how often parosmia occurs revealed that this symptom is mostly linked to postinfectious and posttraumatic olfactory disorders [1] but also occurs in the healthy population, though to a much lesser extent [9] . Parosmia seems to be linked with lower olfactory bulb volumes in patients with hyposmia when compared with hyposmic patients without parosmia [10] .…”

“…Parosmia is mostly associated with postinfectious and posttraumatic olfactory dysfunction while phantosmia does not seem to be particularly related to any kind of cause of olfactory disorder. In most cases, phantosmia has no detectable origin and is diagnosed as idiopathic phantosmia [1][2] .…”

Chronic Rhinosinusitis and Olfactory Dysfunction

“…However, these symptoms seem less frequent when related to sinonasal disease than to other etiologies (i.e. post-infectious, post traumatic) and Reden et al (2007) reported incidence of parosmia and phantosmia in patients with CRS of 28% and 7%, respectively.…”