From the Guidelines
Residual odors and phantosmia (phantom smells) are distinct entities, with residual odors being actual smells that linger in an environment after their source has been removed, and phantosmia being false smell perceptions that occur without any external odor source present. The key difference between the two lies in their causes and the presence or absence of an external odor source. Residual odors have physical causes, such as molecules remaining in the air or on surfaces, and can be detected by others 1. In contrast, phantom smells are neurological phenomena where only the affected person perceives an odor that isn't actually present, and can result from various conditions including sinus infections, head trauma, seizures, migraines, certain medications, or neurological disorders like Parkinson's disease 1.
Some of the conditions that can lead to phantosmia include:
- Sinus infections
- Head trauma
- Seizures
- Migraines
- Certain medications
- Neurological disorders like Parkinson's disease It is essential to note that while residual odors can be addressed through environmental cleaning, ventilation, or odor neutralizers, phantom smells may require medical evaluation and treatment of the underlying condition, which could range from saline rinses for sinus issues to medications like anticonvulsants or antidepressants for neurological causes 1.
Given the potential for phantosmia to indicate an underlying medical condition, if experiencing persistent phantom smells, medical evaluation is recommended as it could indicate a condition requiring treatment. This approach prioritizes the patient's morbidity, mortality, and quality of life by ensuring that any underlying condition is identified and managed appropriately.
From the Research
Definition and Difference
- Residual odor refers to the lingering smell that remains after the initial odor has faded [ 2 ].
- Phantosmia, on the other hand, is a condition where a person perceives a smell that is not actually present in their environment [ 3 ].
Causes and Characteristics
- Residual odor can be caused by various factors, including the persistence of odor molecules in the environment or the brain's ability to recall and recreate the smell [ 4 ].
- Phantosmia can be caused by damage to the olfactory system, neurological disorders, or certain medical conditions [ 5 ].
- Phantosmia can manifest as a range of smells, from pleasant to unpleasant, and can be triggered by various factors, including radiation therapy [ 3 ].
Diagnosis and Treatment
- Residual odor is not typically considered a medical condition and does not require treatment [ 2 ].
- Phantosmia, on the other hand, can be diagnosed through a combination of medical history, physical examination, and diagnostic tests, such as smell identification tests [ 4 ].
- Treatment for phantosmia depends on the underlying cause and can include medications, surgery, or other interventions [ 5 ].
Relationship to Olfactory Dysfunction
- Both residual odor and phantosmia can be related to olfactory dysfunction, which affects approximately 20% of the general adult population [ 2 ].
- Olfactory dysfunction can be quantitative and/or qualitative, and can be caused by various factors, including sinonasal disease, postinfectious or posttraumatic dysfunction, and neurodegenerative diseases [ 2 ].
- COVID-19 has also been shown to cause olfactory dysfunction, including hyposmia, which can persist even after recovery [ 6 ].