What is an odor and taste disorder?
Most people know the feeling from a bad cold: suddenly everything tastes the same, nuances are no longer perceptible. Even the otherwise seductive smell of coffee loses its charm. However, there are people for whom this phenomenon occurs permanently. Others perceive taste and smell differently than most people. There are various forms of this:
- Anosmia: Those affected can no longer smell anything or only very little.
- Hyperosmia/Olfactory intolerance: Those affected are hypersensitive to odors.
- Parosmia: Affected people perceive odors differently than most people.
- Phantosmia: Affected persons perceive odors that do not exist.
- Dysgeusia: The sense of taste is disturbed.
- Ageusia: those affected can no longer taste anything.
Smelling works via the olfactory cells, which are located between the eyeballs inside the nose. Each olfactory receptor in the olfactory cells only matches one of around 350 different odor molecules. The olfactory cells convert the resulting chemical signal into an electrical signal and transmit it to the brain. There, the individual signals are combined to form an “overall odor”.
Our taste is also 80 percent determined by smell. Only 20 percent of the taste experience comes from the taste buds on the tongue, palate and epiglottis. Most of the pleasure is determined by the olfactory receptors in the nose, to which the scent molecules of the food flow through the throat and nose.
Frequency and age
Taste disorders are much rarer than odor disorders. It is estimated that one in 20 people has a more or less severely impaired sense of smell. As we get older, our ability to perceive flavors intensely and in many layers decreases. This is because olfactory cells are lost over the years and the olfactory bulb also transmits less and less information to the brain. Those who get to know few different flavors at a young age lose the ability to distinguish between them. According to a study, around 20 percent of all people have impaired taste perception. 3.8 percent of people smell almost nothing. In more than half of cases, inflammation of the nose and paranasal sinuses is the reason for a visit to the doctor for a taste and smell disorder.
Smell and taste disorders: causes and risk factors
Only very rarely is a sense of smell and taste disorder congenital. In most cases, they are caused by an illness or (rarely) an accident. The causes can be divided into three groups:
- Sinunasal: Those affected cannot smell because the scent molecules do not reach the olfactory cells – for example because the nose is swollen shut. Possible causes include infections, sinusitis, allergies, polyps or a deviated nasal septum.
- Damage to the nerve cells: The taste buds in the mouth or the olfactory cells in the nose do not function properly. Sometimes the olfactory cells are damaged after a viral infection. Tobacco smoke, cocaine or carbon monoxide can disable the sensitive cells, as can radiotherapy during cancer treatment. In the event of a fall or blow to the head, olfactory nerves can be torn off. Some medications can also affect taste buds or olfactory cells.
- Damage to the brain: Sometimes all the olfactory and taste buds work well, but the information cannot be processed properly in the brain. On the one hand, the nerves in the brain can be mechanically injured, for example during an operation on the ear or tooth, in a fall or by a brain tumor that spreads. On the other hand, there are neurological and psychiatric illnesses that can lead to impaired sense of smell and taste. These include Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, certain forms of epilepsy, Huntington’s disease, hypothyroidism and diabetes mellitus. Depression and schizophrenic psychoses are also sometimes accompanied by an olfactory and taste disorder.
In the vast majority of cases, inflammation of the paranasal sinuses or respiratory disorders (respiratory flow disorders) are the reason for an impaired sense of smell and taste. Temporary odor disorders can also occur during pregnancy, with migraines or in people with diabetes mellitus.
Symptoms: Smell and taste disorder develops slowly
In some cases, the loss of sense of smell and taste occurs suddenly: After a fall, you realize that you can no longer smell your lunch or the freshly baked cake. Or you may have a bad cold or the flu and then realize that you still can’t detect smells properly a few weeks later. In many cases, however, a sense of smell and taste disorder is a gradual process: as the nerve cells in either the nose, mouth or brain are gradually impaired, the ability to distinguish smells and tastes slowly diminishes. The difference is often not particularly noticeable. Older people therefore often like to eat desserts and cakes because they can perceive sweet flavors better than sour and bitter ones. Accordingly, a sense of smell and taste disorder often goes hand in hand with obesity. Those affected often have a one-sided diet with few vegetables or whole grain products. At the same time, they are at risk of not noticing spoiled food or escaping gas.
Smell and taste disorder: diagnosis with us
First of all, we try to find out in a detailed conversation how severely your sense of smell or taste is impaired. We would like to know whether you no longer perceive certain scents and flavors. We will also ask you about other illnesses and medications you regularly take, as well as accidents or operations. We then look at the oral cavity and its mucous membranes as well as the nose and its access to the sinuses.
This is followed by smell and taste tests. The following tests are possible:
- Smelling sticks
- UPSI test
- CCCRC test
- Electrical measurements
Test procedure with olfactory pens
Smell pens are often used for the smell test: These emit a specific scent that the person being tested is supposed to recognize. The threshold at which an affected person perceives a scent can also be determined with the olfactory pens.
UPSI test (H4)
In the so-called UPSI test(Universityof Pennsylvania Smell Identification), tiny scent capsules are placed on a piece of paper and “rubbed out” one after the other with a pen.
CCCRC test (H4)
The CCCRC test(Connecticut Chemosensory Clinical Research Center) contains 110 different fragrances in small vials. In addition, the person to be tested is asked to smell butanol in various concentrations and say at what point they perceive the pungent odor.
Electrical measurements for smell and taste disorders
If an affected person is unable to express an opinion about their sense of smell, objective tests are also available. To do this, tiny electrodes on the person’s olfactory mucosa pick up the electrical signals after exposure to specific scents.
In rare cases, magnetic resonance imaging (MRI), computer tomography (CT) or neurological examinations are also recommended.
Smell and taste disorder: prevention, early detection, prognosis
If you want to taste good, you should pay attention to good oral hygiene – this applies to all ages. It is important for children and young people to get to know many different flavors. Parents and caregivers should therefore repeatedly present them with a wide variety of foods and scents in nature.
Training the sense of smell also works for adults: find a “trial course” every day and link the smells directly to words and images. Smell a rose, visualize the rose and say the word in your mind. Or think about what Grandma’s stew smelled like back then, or the freshly mown grass on vacation. Try to describe the odors as accurately as possible.
If you notice that certain things smell and taste different than before, or if everything tastes the same, then you should come and see us.
Progression and prognosis of smell and taste disorders
In some cases – for example after a viral infection – the smell and taste disorder disappears on its own after a while. However, there is no effective help for congenital or age-related impairments. If other illnesses or medications are the cause, the smell and taste disorder may disappear again once the cause has been treated. Daily training of the taste and olfactory nerves is definitely helpful. A varied diet without ready-made products can also strengthen the ability to smell and taste.
Smell and taste disorders: treatment depending on the cause
If another disease is the cause of the smell and taste disorder, this must be treated.