Classification of olfactory disorders
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Olfactory disorder (dysosmia) |
Definition |
| Quantitative |
Hyperosmia |
pathologically increased ability to smell |
| |
Normoosmia |
normal olfaction |
| |
Hyposmia |
Decreased ability to smell |
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Anosmia |
- Complete anosmia: complete loss of the ability to smell.
- Partial anosmia: significantly reduced sensitivity to a particular odorant / group of odors compared to the normal population (usually without pathological significance).
- Functional anosmia: very significant limitation of olfaction (includes both the complete loss and the presence of a small residual perception).
|
| Qualitative |
Parosmia |
Altered perception of odors in the presence of a stimulus source |
| |
Phantosmia |
Perception of odors in the absence of a stimulus source |
Sinunasal (sinus-related) olfactory disorders are distinguished from non-sinunasal olfactory disorders:
| Sinunasal olfactory disorders (well treatable according to the “EPOS Guidelines”). |
Non-sinunasal olfactory disorders |
| Inflammatory causes |
- Infectious: e.g. chronic recurrent rhinosinusitis (RS).
- Non-infectious: allergy; toxic-irritant; post-infectious; idiopathic.
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- Congenital (congenital): e.g., Kallmann syndrome (olfactogenital syndrome), aplasia of the bulb olfactoriusPrognosis: no improvement.
- Postinfectious: viral infectionsPrognosis: improvement in 60-70% of cases over the course of years.
- Posttraumatic: traumatic brain injury (TBI)Prognosis: improvement in 20-30% of cases over the course of years.
- Toxic: formaldehyde, carbon monoxide (CO), pesticides, tobacco smoke or cocaine; radiatio (radiation therapy); drug side effects (see below differential diagnoses)Prognosis: good
- Other causes: e.g., internal diseases (e.g., hypothyroidism (hypothyroidism), type 2 diabetes mellitus; kidney and liver diseases), neurological diseases disorders (Alzheimer’s disease, Parkinson’s disease, multiple sclerosis) or psychiatric diseases (e.g., depression, schizophrenic psychosis)Prognosis: improvement depending on the underlying disease.
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| Non-inflammatory causes |
- Anatomic: when the olfactory cleft is obstructed by bony deformities, foreign bodies, or rhinoliths (nasal calculi); obstructing septal deviation (deviation of the nasal septum), tumors.
- Non-anatomical: e.g., nervous-endocrine causes.
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| Other causes |
- Post-infectious and post-traumatic olfactory disorders.
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