The diagnosis of a taste disorder

If a taste disorder is suspected, a detailed anamnesis should be carried out by the doctor, as important information about a possible cause can already be obtained.Following the patient’s medical history and examination, the presence of a taste disorder should be verified with tests. Verification of taste: Our ability to taste can be verified with two types of tests. On the one hand there are the so-called subjective test procedures, which presuppose that the patient is fit and can give information about what he/she has tasted, and on the other hand there are objective test procedures, which are used when the patient himself/herself cannot cooperate and cannot give any information, as is the case with small children or dementia patients.

Our ability to taste can be checked by means of a variety of tests. For example, there is the so-called three-drop method, which can be used to determine the threshold at which one perceives a certain taste. To do this, the person affected has to find out from three drops administered, which drop tastes like something specific and what that drop tastes like.

If one tastes nothing at the beginning, the concentration of the flavoring substance is increased until the taste is perceived. Of course, there are also tests that check whether certain flavours can be identified. For this purpose, flavors are administered in liquid (spray or drops) or solid form (for example wafers) and it is checked whether the tastes can be recognized by the patient.

There is also the possibility of having the patient indicate the perceived strength of a particular taste. There are certain scales for this from weak to strong. Volumes can also be used as a comparison to the perceived intensity.

Tasting can also be checked by other methods and a taste disorder can thus be objectified. One of these methods aims at measuring brain waves after stimulation with a flavouring agent. It is called electroencephalogram (EEG).

A so-called electrogustometry can also provide information about a nervous defect. Here, the electrical perception threshold is determined on both sides of the tongue by stimulation with currents in the microampere (μA) range. In electrogustometry, it is always important to compare the sides of the tongue with the healthy side, since the electrical perception threshold varies greatly from person to person and therefore cannot be compared between people. Central causes for a taste disorder can be detected by means of magnetic resonance imaging (MRI) of the skull.