Olfactory function assessment
Both the olfactory threshold and the odor discriminative ability were
assessed. All tests were conducted in a quiet room, by the same
operators. Olfactory function assessment was carried out by means of the
Connecticut Chemosensory Clinical Research Center orthonasal olfaction
test (CCCRC) [7-11]. The CCCRC is a simple, validated and widely
used test, that includes a butanol threshold assessment and an odor
identification test using common odors.
Threshold testing was performed presenting solutions of N-bunatol in
deionized waters, decreasing concentration in 8 steps. The strongest
butanol concentration was 4% in 60 mL of deionized water (bottle 0).
Each other bottle (from 1 to 8) contained a subsequent 1:3 N-butanol
dilution. Two identical squeezable bottles were presented to the
patient: one containing the N-butanol solution, Starting from the major
dilution, and the other filled with deionized water. The patient was
then asked to close one nostril and squeeze the bottle immediately below
the other, reporting which of the two bottles smelled most. The
threshold was identified when the subject gave the correct answer 4
times. In case of error, the next most concentrated solution was given
to the patient. The threshold was quantified for each of the two
nostrils with a score from 0 to 8 corresponding to less concentrated
bottle that the patient was able to correctly detect. The average
between values of the two nostrils expressed the overall score.
For the identification test, common odorants, familiar to the Italian
population [Table 1], were placed inside 180 mL opaque jars covered
with gauze. One at a time, the samples were presented to the patient in
the same way as the threshold test. Therefore, the patient was asked to
identify the odorant on a list containing the 10 test items and 10
distractors [Table 1]. Score ranged from 0 to 10 and was obtained
from the average of the two nostrils.
The threshold and identification test scores, after being analyzed
separately, were finally converted into the CCCRC composite score. The
scoring system is shown in table 2 [Table 2].