Refers to the inability to smell and hyposmia is a decreased ability to smell.
The ability to smell involves the nose and brain in complex processing.
As air passes into the nose, odor molecules bind to the receptors of olfactory nerves.
Olfactory nerves are found in the top of the nasal cavity known as the olfactory epithelium.
Stimulation of olfactory nerves causes them to transmit a signal to the brain, where it is subsequently processed into a scent the person can recognize.
Smell disorders affect about 15 per 1000 people and increases with age.
Smell disorders include:sinoonasal disorders such as allergic rhinitis, nasal polyps, head trauma, and viral infections.
Anosmia can be congenital, related to dementia as in Parkinson’s disease or Alzheimer’s disease and also idiopathic.
Sudden onset has been reported in Covid-19 infection.
Diagnosis requires history such as a viral illness, trauma or nasal complaints.
Examination with nasal endoscopy is required to look for obstructive causes such as polyps or swelling, and imaging such as CT scan or MRI of the upper airways.
Treatment depends on the cause of the process.
In up to 2/3 of cases associated with viral illness and anosmia resolves on its own.