Physiology of sense of smell -> Olfactory disorders
Olfactory disorders
When we are considering types of olfactory disorders, two main categories of disorders can be distinguished:
- 1. Quantitative ones (degree of sensitivity to odors)
- 2. Qualitative ones (odor distortion)
Quantitative distortions
- ⚈ Hyperosmia is a hypersensitivity to odors
- ⚈ Hyposmia refers to reduced sensitivity to odors
- ⚈ Anosmia is a lack of smell / a complete loss of sensitivity to odors
Qualitative distortions
Dysosmia* is a common name for distorted perception of odors:
- ⚈ Parosmia is a distorted perception of familiar odors
Some forms of parosmia:
- Cacosmia (kakosmia) is a persistent sensation of unpleasant odors, even if the actual aromas are pleasant or neutral
- Euosmia is a persistent sensation of pleasant odors
- ⚈ Agnosia means the inability to recognise previously familiar smells
- ⚈ Phantosmia is a sensation of odors that are not actually present (olfactory hallucinations)
* Also, dysosmia sometimes means any disorder related to the sense of smell, including quantitative ones - hyperosmia, hyposmia and anosmia.
Loss of smell can be temporary or permanent.
With age, the sensitivity to odors decreases, and in some cases this is a symptom of other serious diseases (Alzheimer's, Parkinson's, covid-19 etc.)
Statistics on diseases of the olfactory system
According to the website nidcd.nih.gov, about 1–2% of North Americans see a doctor with a sense of smell issue. As a rule, the number of requests increases with age. Most of the complaints come from men.
On average, in the world, 5-19% of the population over 20 years old and 25% of the population over 53-55 years old face olfactory problems (these statistics are from various sources before the coronavirus pandemic).
Also up to 85% of patients who have recovered from covid-19 have a sense of smell impairment. Approximately 20-65% of sick people seek help. Recovery of sensitivity to odors depends on the degree and type of damage of the olfactory analyzer, and it can take from several weeks to several months.
Causes of loss of smell
Natural reasons
- ⚈ Age
- ⚈ Congenital disorders
The issues arising during life
1. Diseases and injuries
- ⚈ Infections
- ⚈ Allergies
- ⚈ Dental problems
- ⚈ Polyps in the nasal cavity
- ⚈ Hormonal disorders
- ⚈ Diabetes mellitus
- ⚈ Avitaminosis
- ⚈ Renal failure
- ⚈ Oncological diseases
- ⚈ Age-related disorders and psychogenic diseases
- ⚈ Head injury
- ⚈ High level of cholesterol [new research, 2021]
2. Consequences of treating other diseases
- ⚈ Surgical operations
- ⚈ Radiation to the head and neck area
- ⚈ Drug use (antibiotics, histamine, etc.)
3. Lifestyle
- ⚈ Smoking
- ⚈ Inhalation of drugs
- ⚈ Exposure to certain chemicals (insecticide, solvents) on olfactory epithelium receptors for a long time
Smell recovery
Otolaryngologists are directly involved in the diagnosis and treatment of the sense of smell. Testing is done using specific scent kits and / or an olfactometer inserted into the nostril to release a portion of the scent. In some cases, laboratory tests, computed tomography and MRI are prescribed.
Based on the causes of the onset of diseases, appropriate treatment is selected, including surgical one and medication.
Very often, odor loss is one of the symptoms of other diseases, and then the detection of the root cause is already carried out, followed by the appointment of treatment.
Consequences of loss of smell
- ⚈ Partial or complete loss of taste
- ⚈ Loss of appetite
- ⚈ Decreased quality of life and depression
- ⚈ Impairment of the hazard warning systems (insensitivity to the smell of fire, explosive substances, poisonous gases)
See also:
Physiology of the sense of smell | Odors and Covid-19 | Parosmia