Pastry chefs, wine stewards or firefighters rely on the Olfactory nerve for pleasure, income and safety. Call it aroma, bouquet or fragrance — these are other ways of saying odor.
“I love the aroma of warm apple pie”
“This wine has a wonderful bouquet.”
“I smell smoke.”
The Olfactory nerve, or smell nerve, responds to different chemicals in the air. This allows the six million receptor cells in the nose to relay the information by way of the Olfactory nerve to the brain for interpretation.
We also smell through the mouth. When you chew food or take a sip from a flavorful beverage, volatile chemicals are delivered to the back of the mouth. The aromas go upwards towards the nose and excite the receptor cells of the Olfactory nerve.
But things can go wrong. The next time you sit down to have lunch or dinner, pinch your nose before chewing or swallowing. Next chew and swallow. This is how food and drink taste to people with anosmia day in and day out.
Anosmia is the total loss of the sense of smell. It can be temporary or permanent. When the loss is permanent, these individuals miss out on the fragrance of flowers, the aromas of freshly baked breads or the bouquet of a cabernet. They also cannot appreciate the danger signals put out by smoke or a gas leak. It can affect their mood and emotional wellbeing.
The notion that as we get older we smell less is not always true. However, after the age of 65 there is evidence to suggest that patients with anosmia, no sense of smell, are associated with increased mortality compared to those with a healthy sense of smell. Below are a classification and examples of the causes of anosmia.
Anosmia
A) Intranasal
Conductive Loss
Blockage of nasal passages
Are there nasal polyps, allergies, deviated septum, benign or malignant tumors causing the nasal obstruction?
The blockage prevents the airborne chemicals or those in the back of the mouth from reaching the Olfactory nerve
Nerve Loss — Sensorineural Loss
Damage to the Olfactory nerve endings in the upper — back part of the nose
Is there head trauma, a bacterial or viral infection, airborne toxin or vitamin deficiency?
The Olfactory nerve is not functioning. It cannot relay the odorants, the chemical stimuli, to the brain for interpretation.
B) Intracranial
CNS — Central Nervous System
Is there trauma, infection, tumor or neurodegenerative disease? The latter attacks the nerve cells in the brain (e.g. Parkinson Disease, Alzheimer Disease or ALS-Lou Gehrig Disease).
The above are examples that damage the sense of smell in certain regions of the brain.
Workup — ‘Diagnosis’
- History
The medical history is an important first step in the diagnosis of anosmia. Have you had previous sinus or nasal surgery, head trauma or a history of sinusitis? Are you a smoker? What medications are you taking? - Physical Exam
Is there a blockage of the nasal passageways? Is there nasal drainage? - Laboratory Tests
Is there a vitamin or mineral deficiency? - Radiographic Imaging
A CT is used in this instance to rule out nasal — sinus disease or a facial fracture.
An MRI is order to rule out a problem in the brain.
Testing of Olfactory Nerve
A doctor may perform a basic test in the office.to evaluate the Olfactory nerve. One nostril is occluded and the odorant from a vial is presented to the patient. The patient’s ability to detect the scents of coffee, chocolate, cinnamon, tobacco or oil of lemon can be used as an initial test. The individual suffering from anosmia when asked to identify, for example, the smell of coffee might say, “I can’t smell that!”
There are several standardized smell tests commercially available. One such test is the University of Pennsylvania Smell Identification Test. The UPSIT’s scratch-and-sniff test is used to evaluate these patients.
Treatment
Conductive Loss
Treat the underlying problem with medication or surgery.
Sensorineural Loss
Vitamin A, zinc supplementation, estrogen and steroid medications have been used for anosmia with limited to no success.
The common causes of anosmia are nasal obstruction, sinusitis, post-influenza infection and trauma to the head and nose. The cause of anosmia is unknown in approximately one out of five cases.
Psychological counseling is useful because anosmia can lead to a change in one’s dietary habits, to less social interaction and depression.
People with anosmia have taken practical steps. They’ve added smoke detectors, the use of carbon monoxide detectors, put in place fire extinguishers or switched from gas appliances to electric appliances. In short, psychological counseling, practical advice and other resources are useful tools available to these patients.
References
- Jing Shen, MD; Mathew Ryan, MD; Olfactory Dysfunction and Disorders; UTMD, Nov.26, 2003
- Anosmia Foundation
- Anticaglia, Joseph R. Taste and Smell; The Olfactory Nerve and the Five Senses; HC Smart, 2016
This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.