The following forms of dysosmia (olfactory disorders) can be distinguished:
Quantitative olfactory disorders:
- Anosmia – failure of the ability to smell.
- Hyposmia – reduction of the ability to smell.
- Hyperosmia – Increased ability to smell or hypersensitivity to olfactory stimuli.
Qualitative olfactory disorders:
- Parosmia – altered olfactory perception.
- Olfactory agnosia (synonym: olfactory agnosia) – inability to distinguish odors despite preserved olfactory perception.
- Heterosmia – inability to distinguish odors.
- Cacosmia – mis-smelling; odors are mistakenly perceived as unpleasant.
- Euosmia – unpleasant odors are perceived as pleasant
- Phantosmia – sensory cells of the olfactory mucosa trigger an excitation without the presence of an odor stimulus (olfactory hallucination).
- Pseudosmia – olfactory illusion
Other forms of dysosmia:
- Respiratory dysosmia – mechanical obstruction of air supply to the regio olfactoria (olfactory mucosa).
- Central dysosmia – olfactory disorders associated with damage to higher processing centers.
Warning signs (red flags)
- Olfactory disturbances → think of: Alzheimer’s disease (often olfactory disturbance is the first symptom).
- Olfactory dysfunction as a marker of health! A reduced ability to smell is associated with increased mortality.
