Although the sense of smell (also known as olfactory function) goes unnoticed and unappreciated by most of society; it is estimated that one out of a hundred Americans suffers from complete loss of smell. There are several known olfactory disorders. The most common are anosmia, the loss of smell; and hyposmia, the diminished sense of smell. Some people also suffer from hyperosmia, an increased sense of smell; parosmia, misperception of certain smells; and phantosmia, the presence of a smell that isn’t there. These disabilities may sound like a joke, but for many people they are a serious issue that affects their everyday life.
How smell works
The sensation of smell occurs when molecules enter your olfactory receptor cells located deep in the nose. Tens of millions of olfactory receptor cells line deep in the nose, olfactory receptor cells are very specialized; each cell has one receptor that reacts with several molecules, some molecules cause a greater intensity in receptors than others. Once molecules are detected by the receptors, an electrical impulse is sent to your olfactory bulb. Within your olfactory bulb there are around two thousand glomeruli which receive signals from particular receptors. The glomeruli serve as important waypoints for transferring signals from the olfactory receptors to the olfactory epithelium. The olfactory epithelium is where the network of olfactory neurons resides and where the odorant pattern is decoded by the brain and perceived as an aroma.
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Several factors can affect a person’s ability to smell. A large factor is age, as we age the sense of smell declines. Also, females usually have better olfaction than males. Alcohol dependence and smoking have been shown to decrease olfactory function. A large factor in olfaction is medical history, Even fairly common issues like allergies, sinonasal infections, or head injuries can effect a person’s ability to smell.
Effects/ Problems related with olfactory dysfunction
Despite the public’s general ignorance of the sense of smell, people with olfactory disorders face several problems. Olfactory impaired people often report feelings of depression and less satisfaction in life. The investigation held by Takaki Miwa et al. “Impact of Olfactory Impairment on Quality of Life and Disability.” shows people with better smell are more likely to report higher levels of satisfaction and less likely to report dissatisfaction than the impaired people. Since smell is closely tied to memories, and adds zest and variety to everything we do; people who lose their ability to smell often feel the world has become drab and boring. As one person suffering from anosmia puts it, “Sense of smell? … I never gave it a thought. You don’t normally give it a thought. But when I lost it – it was like being struck blind. Life lost a lot of its savour – one doesn’t realize how much “savour” is smell. You smell people, you smell books, you smell the city, you smell the spring – maybe not consciously, but as a rich unconscious background to everything else. My whole world was suddenly radically poorer…”
People suffering from olfactory dysfunction often report several dangers and problems in daily living. One significant danger resulting from olfactory impairment is the inability to detect smoke or leaking gas. Obviously this could be an immediate danger. Another common problem is eating and nutrition. A questionnaire of 420 olfactory impaired patients reported that 75% had impaired detection of spoiled foods, 52% had impaired eating, 49% had impaired cooking, 46% enjoyed eating less and 38% had problems buying fresh food. Although olfactory dysfunction does sometimes affect weight and body mass index, the result of this effect is unclear. Many people lose appetite due to their lack of taste; weight loss and even anorexia have been known to occur. However, some people adapt their diet to make up for their loss of taste by eating very flavorful food. This can lead to weight gain if too many sugar or fat rich foods are consumed.
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Many people experience anxiety and discomfort from their loss of smell. Some people have insecurities from being unaware of their body odor. And many have problems with everyday tasks like gardening and using cologne or perfume.
Causes of olfactory impairment
Olfactory impairments can stem from many different causes. The types of olfactory impairments can generally be classified into three groups: nasal obstruction impairing odor transportation, damage to the epithelium, and central olfactory neural impairment.
Several issues that cause olfactory impairment are classified into the nasal obstruction problems. The most common is chronic nasal inflammation such as chronic sinusitis and chronic rhinitis. Sinusitis is nasal inflammation caused by a viral, bacterial, or fungal infection. Rhinitis is inflammation on the nasal mucous membrane caused by infection its main symptom being excess mucus and runny nose. When these illnesses become chronic for long time periods nasal polyps may occur. Nasal polyposis is an inflammatory lesion in the nose which often is the result of sinusitis or rhinitis. When these lesions occur on the olfactory mucosa, where the olfactory receptor cells are located; olfactory impairment can occur.
Damage to the neuroepithelium is also a common cause of olfactory dysfunction. A major cause of neuroepithelium damage is the inhalation of harmful chemicals. Chemicals with highly alkaline pH such as ammonia, benzene, formaldehyde and acetone can be harmful to the epithelium. Workers exposed to these substances frequently, suffer a higher risk of developing olfactory dysfunction. Also, workers exposed to dust from many industries, such as grain, lead, coal, silicone, cotton, paper, and chromium are at risk for developing olfactory dysfunction. The use of some medications such as Zicam and certain nasal sprays can cause damage to the epithelium.
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Several problems can cause olfactory neural impairment. A common cause is neurodegenerative disorders. Many neurodegenerative disorders can cause olfactory dysfunction including Alzheimer’s, Parkinson’s, dementia, lupus and multiple sclerosis. The area of the brain where smell is processed is the same area affected by neurodegenerative diseases; this is most likely the cause of the impairment. Olfactory impairment is often a precursor to the neurodegenerative diseases and can be used as a warning.
Other common causes
An extremely common cause of olfactory dysfunction is head injuries. Olfactory dysfunction can occur in several different ways from head trauma. The trauma can cause contusion or hemorrhage in the areas of the brain related to smell. Shearing of olfactory filaments can occur. Also, the sinonasal tract can be damaged. Head trauma sufferers sometimes don’t realize an impaired sense of smell for weeks or months.
Many different tumors can impair olfaction. Intranasal tumors such as papilloma and hermangioma can cause impairment. Also, intracranial tumors and lesions such as Foster Kennedy syndrome, olfactory groove meningiomas, frontal lobe gliomas, and epilepsy-related lesions can cause dysfunction.
Treatment of olfactory dysfunction
In cases where nasal obstruction is involved; treatment can be sought through allergy control, topical cromolyn, topical and systematic corticosteroids, and surgery to fix the obstruction
Many cases of olfactory impairment are not effectively treatable. However, new and experimental methods of treatment are frequently advancing. Recent studies have shown improved olfactory function through neurofeedback treatments. Also new types of surgery and steroid treatments have shown promise in helping all kinds of .olfactory impairment
Smell is an important sense that plays a huge role in our health. The loss of smell can be detrimental to one’s health in a variety of ways. Smell is important to our perception of everyday life, but smell can be impaired by many different factors. Though treatment is available, it is limited, and depends on the specific condition. Overall, it is important to appreciate your olfactory function and treat it with care.
Three main facts
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1. Olfactory impairments can cause a decreased Quality of Life.
2. Olfactory impairment can be a precursor to neurodegenerative diseases which can help start treatment early.
3. Olfactory impairment can make eating less enjoyable.
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