Document Type


Publication Date



Poster presentation at 26th Annual Meeting of the Association of Chemoreception Sciences in Sarasota Florida, April 21-25, 2004.


Because there is the possibility of unilateral loss of olfactory function or differential degrees of olfactory dysfunction in the two nostrils, unilateral tests of olfactory threshold sensitivity are routinely included in many chemosensory clinical test batteries to supplement bilateral tests (e.g., Cain et al., 1988; Hummel et al., 1997). Surprisingly, however, the results of unilateral testing in patients with chemosensory complaints have not been extensively reported. Thus, it is unclear how useful these additional measures are in characterizing individual patients.

A number of studies have assessed unilateral olfactory thresholds in largely non-clinical populations. There is substantial disagreement concerning general asymmetries in left-right olfactory sensitivity; however, two large, recent studies both reported that bilaterally obtained threshold values are equivalent to those obtained on the better functioning side of the nose (Betchen & Doty, 1998; Frasnelli et al., 2002), suggesting that bilateral facilitation does not occur at the threshold level in olfaction. Whether this finding holds true in patients with olfactory dysfunction is not known.

In the present study, we address these questions by examining unilateral olfactory thresholds obtained from a large sample of non-anosmic patients referred to the Monell-Jefferson Taste & Smell Clinic for evaluation of chemosensory dysfunction.