We might take our sense of smell for granted, but there is a possibility that we lose it for good. Anosmia or the complete loss of sense of smell can be temporary or it can last a lifetime.
Causes of Anosmia
Nasal and sinus obstruction related to nasal polyps, tumors, or mucosal swelling due to chronic rhinitis.
Congenital loss of sensation of smell is probably caused by the degeneration of the olfactory epithelium during the developmental process.
- Epilepsy and some psychiatric disorders also manifest loss of smell.
- Upper respiratory infection causes nasal obstruction, but it will resolve spontaneously after one to three days once the airway becomes patent.
- Head trauma, minor or major, causes about 5-10% of anosmia due to loss of olfactory receptors causing complete loss of smell.
Anosmia can also be caused by intake of medications such as amoebicides, anthelmintics, anesthetics, anticoagulants, antihistamines, antimicrobial agents, anti-thyroid agents, opiates, muscle relaxants, hypoglycemic drugs, etc.
- Surgical alteration and manipulation of the airflow path around the olfactory nerves may also affect olfactory ability such as rhinoplasty and other cranial surgeries.
- Old age seems to be a factor in developing anosmia as well, from the dementia-related diseases and the aging process itself.
Lastly, there are still cases of idiopathic loss wherein after extensive tests have been exhausted, there are no specific causes identified.
Probing of the history of possible causes of nasal obstruction such as history of trauma, infection, surgeries, or use of medications provide useful information. Physical examination would help identify anosmia. Series of chemosensory testing of gustatory and olfactory abilities may also prove to be useful. Rhinomanometry and nasal endoscopy are usually done. CT scans are used in identifying anatomic deformities or obstructions. Biopsies of the olfactory area can find out the presence of olfactory receptors or their decrease in size.
Alternatively, magnetic resonance imaging (MRI) scans can identify the volume of olfactory bulbs, which can reveal a decrease in volume and directly correlates with hyposmia or anosmia that is usually seen with old age.
Anosmia management depends on the identified cause of olfactory loss. Mainstay treatments include medical therapy including intranasal and systemic steroids, antibiotics, and allergic therapy. The obstruction of the airway may warrant removal of the tumor or polyp. If the olfactory loss is caused by intake of medication, usually discontinuation of the offending medication would restore the loss of smell.