Anosmia – Types, Causes, Treatment, and Prevention

Definition

Anosmia is the full loss of smell. Anosmia can be a temporary or permanent condition. You can partially or completely lose your sense of smell when the mucus membranes in your nose are irritated or obstructed such as when you have a severe cold or a sinus infection, for example. But if the inability to smell isn’t related to a cold or sinus infection, or it doesn’t return after congestion clears, you should see a doctor. It could be a symptom of another issue.

The sense of smell is important to overall health and nutrition since diminished sensations can lead to poor appetite and malnutrition, especially in the elderly. An altered sense of smell may pose other health-related problems. People with anosmia may accidentally consume soured or rancid foods because they are unable to detect odors that signal spoilage. Those with anosmia may also be unaware when they are breathing toxic, polluted, or smoke-filled air.

Although rare, some people are born without a sense of smell, which is a condition called congenital anosmia. This occurs when there is either an inherited genetic disorder or abnormal development of the olfactory system (the body’s sensory system for smell) occurring before birth. Unfortunately, there is no cure for congenital anosmia.

Types of Anosmia

There are three types of Anosmia:

Temporary: Temporary anosmia is common as it is caused due to a congested nasal pathway that we go through during cold, flu, sinus, etc.

Permanent: This anosmia causes permanent smell loss due to various reasons such as accident, advancing age, etc.

Congenital: This anosmia happens in one out of 10,000 adults where they are born with this condition.

Anosmia risk factors

Different factors that are known to interfere with the smell sense include:

Chemicals– A wide range of industrial chemicals, including heavy metals, inorganic and organic compounds, acids, and pollutants.

Diseases of the hormonal system– Such as diabetes, Cushing’s syndrome, and hypothyroidism.

Diseases of the nervous system– Such as Alzheimer’s disease, multiple sclerosis, migraine, Korsakoff syndrome, brain tumors, brain lesions, and epilepsy.

Drugs– Stimulants (such as amphetamines and cocaine), depressants (such as morphine), some antibiotics, and other drugs, including the vasoconstrictors in nasal sprays.

General diseases– Such as bronchial asthma, leprosy, and cystic fibrosis.

Trauma- Including blows to the head or injuries to the nose.

Causes of Anosmia

Some common causes of anosmia include:

Chronic nasal-sinus disease, e.g., rhinitis (inflammation in the nose caused by viral, bacterial, or fungal infections), nasal polyps, and/or chronic sinus infections can block the passage of odor molecules to the smell receptors or interfere with how the receptors detect odors.

Viral respiratory infections (common colds) – Can damage or destroy the smell receptor cells.

Head injury– Can sever the olfactory nerve fibers that send smell information to the brain and/or damage parts of the brain that process smell information

Aging– Repeated exposure of the olfactory receptors to environmental airborne toxins can damage the smell receptors and/or the receptor cells can lose the ability to regenerate

Congenital or in-born causes – The reasons for this are unknown at this time.

Anosmia Symptoms

Anosmia and taste are linked. Many individuals that lose their sense of smell, or those who are born without a sense of smell, also lose their ability to taste. Scientists believe this is due to the fact that people “taste” food by the smell, texture, and temperature. In addition, many people are able to recognize their foods or beverages by smell. Coffee is a beverage that is not only enjoyed by taste, but also by smell.

If you have many symptoms and signs that accompany your anosmia, you should consider an evaluation from nose and mouth specialist. Symptoms to be concerned about include:

• Inability to smell
• Inability to taste
• Stuffy nose and congestion
• Persistent sneezing, nasal drainage, and itchy watery eyes
• Weight loss
• Headaches
• Nose Bleeds

Complications of Anosmia

Complications you may experience if you lose your sense of smell:

• An inability to taste the food, which can lead to eating too much or too little
• An inability to smell spoiled food, which can lead to food poisoning
• The increased danger in the event of a fire if you cannot smell smoke
• Losing the ability to recall smell-related memories
• Loss of intimacy due to the inability to smell perfume or pheromones
• Losing the ability to detect chemicals or other dangerous odors in your home
• Lack of empathy from family, friends, or doctors
• Inability to detect body odors
• Mood disorders such as depression
• Lack of interest in social situations, which might include being unable to enjoy the food at a social gathering

Diagnosis and test

The loss of smell is difficult to measure. Your doctor may ask you some questions about your current symptoms, examine your nose, perform a complete physical examination, and ask about your health history.

The diagnosis is made clinically from the history of a poor sense of smell along with a clinical exam of the nasal passage.

Physical examination: The nasal cavity is examined thoroughly to look at the structure and identify the presence of inflammation or blockage. The sense of smell is examined by asking the individual to identify several common odors while blindfolded.

Laboratory investigations: blood tests to look for vitamin deficiencies, blood sugar levels are performed to screen for illness

Imaging: Scans of the head and brain using CT or MRI are performed to look for any structural defects, tumors or neurological disease and trauma.

Treatment and medications

Fifty percent of anosmia cases can be treated and symptoms reversed, depending on the underlying cause. And in cases that cannot be reversed, symptoms can often be reduced with treatment.

Some anosmia treatments that can help if your loss of smell is from obstruction:

• A decongestant
• An antihistamine
• Steroidal nasal spray
• Sinus surgery for nasal obstruction, chronic sinusitis or nasal polyps
• Short term course of oral steroids

More recent innovative therapies that have shown promise in controlled studies in improving the sense of smell include:

• Intranasal theophylline spray
• Smell therapy.

Both are offered as part of a comprehensive therapeutic regimen.

Prevention of Anosmia

Avoiding certain chemicals, certain drugs, and not smoking might help prevent you from losing your sense of smell.

Also, since anosmia can be one result of sustaining a brain injury, it’s yet one more reason to be extra careful when playing dangerous sports, driving, or taking part in similar risky activities.

If you do have anosmia, you can make your environment safer by:

• Making sure your smoke alarms are working
• Checking that cookers, barbecues, and electrical appliances are turned off properly
• Reading food expiry dates carefully