Patient-administrated olfactory and gustatory test
Both olfaction and taste were assessed in all the patients. The
olfactory threshold was determined using solutions with a decreasing
concentration of denatured ethyl-alcohol. Ethyl-alcohol has an olfactory
threshold 10 times lower than N-butyl-alcohol [8], therefore the
patient was asked to prepare a 40% in 100 mL water solution (bottle 0)
using a using a syringe or a graduated container. In the following
bottles (from 1 to 8), the patients diluted a part of the previous
solution with two parts of water, thus obtaining solutions with
consequent 1:3 dilutions. Finally, a control bottle was filled with
water only. The test was performed by asking the patient to smell the
alcohol-containing bottle, starting with the less concentrated (bottle
8), reporting if he found any differences compared to the control
bottle. In case of a negative answer, the examination continued with the
consequent bottle.
The discriminative test was performed asking the patient to find some
commonly used odorants [Table 1]. Therefore, the subject smelled an
odorant for each of the 7 groups providing an assessment of the
discriminative ability from 0 (no discrimination) to 10 (normal
discrimination). The discriminatory score was obtained from the average
of the ratings of the 7 odorants.
The threshold and identification test scores, after being analyzed
separately, were finally converted into a composite score. The scoring
system is shown in table 2 [Table 2].
For the evaluation of the gustatory function, the patient was asked to
prepare four solutions, one for each primary taste [9-11]:
- Salted solution: 30 g of table salt in 1 liter of water.
- Sweet solution: 60 g of refined sugar in 1 liter of water.
- Sour solution: 90 mL of 100% lemon juice in 1 liter of water.
- Bitter solution: unsweetened decaffeinated coffee.
The patient was asked to put in mouth a tea spoon of each solution,
reporting the quality of taste perception, scoring it from 0 (ageusia)
to 10 (normal perception). The bitter solution comes always the last
[9-10]. The overall test score was obtained by the average of the
values reported for each of the primary tastes. The scoring system is
reported in table 3 [Table 3].