Anosmia


 * Anosmia can be either temporary or permanent.
 * Temporary anosmia is caused by any condition that causes swelling and obstruction of the nasal passages and sinuses by irritation.
 * Permanent anosmia is caused by damage or destruction of the olfactory neuroepithelium or part of the olfactory nerve
 * A related term, hyposmia, refers to a decrease in the ability to smell, while hyperosmia refers to an increased ability to smell. Some people may be anosmic for one particular odor. This is called "specific anosmia" and may be genetically based.
 * While termed as a disability, anosmia is often viewed in the medical field as a trivial problem. This is not always the case&mdash;esthesioneuroblastoma is a very rare cancerous tumor originating in or near the olfactory nerve.

Epidemiology and Demographics

 * In the United States, more than 2 million people suffer from anosmia

Causes
A temporary loss of smell can be caused by a stuffy nose or infection. In contrast, a permanent loss of smell may be caused by death of olfactory receptor neurons in the nose, or by brain injury in which there is damage to the olfactory nerve or damage to brain areas that process smell (see olfactory system). The lack of the sense of smell at birth, usually due to genetic factors, is referred as congenital anosmia. Anosmia may very occasionally be an early sign of degenerative brain diseases such as Parkinson's disease and Alzheimer's disease. Another specific cause of permanent loss could be from damage to olfactory receptor neurons due to use of certain types of nasal spray, i.e. those that cause vasoconstriction of the nasal microcirculation. To avoid such damage and subsequent risk of loss of smell from vasoconstricting nasal sprays, they should be used for only a short amount of time and only when absolutely necessary. Non-vasoconstricting sprays, such as those used to treat allergy related congestion are safe to use for extended periods of time.


 * Upper respiratory tract infection (e.g., sinusitis or the common cold)
 * Nasal polyps
 * Smoking
 * Head trauma, damage to the ethmoid bone
 * Dementia with Lewy bodies
 * Parkinson's Disease
 * Alzheimer's Disease
 * Toxins (especially acrylates, methacrylates and cadmium )
 * Old age
 * Kallmann syndrome
 * Laryngectomy with permanent tracheostomy
 * Esthesioneuroblastoma is an exceedingly rare cancerous tumor that originates in or near the olfactory nerve. Symptoms are anosmia (loss of sense of smell) often accompanied by chronic sinusitis.

Anosmia can also be caused by nasal polyps. These polyps are found in people with allergies, histories of sinusitis & family history. Individuals with Cystic Fibrosis often develop nasal polyps.

Associated conditions

 * Cystic Fibrosis
 * Kallmann syndrome
 * Zinc deficiency
 * Parkinson's disease
 * Alzheimer's disease
 * Cadmium Poisoning
 * Holoprosencephaly
 * Allergies

Complete List of Differential Diagnoses

 * Central nervous system (CNS) disorders
 * Congenital disorders
 * Endocrine disorders
 * Head/facial trauma
 * Iatrogenic
 * Illicit drugs
 * Nasal and sinus disease
 * Neoplasms
 * Poisoning
 * Post-upper respiratory viral infection
 * Sjogren's Syndrome
 * Vitamin deficiencies

Smell vs. taste
It should be emphasized that there are no more than 6 distinctive tastes: salty, sour, sweet, bitter, umami and possibly fatty acids. The 10,000 different scents which humans usually recognize as 'tastes' are often actually 'flavor', which many people who can smell confuse with taste. This sense of 'flavor' is greatly diminished by a loss of the sense of smell, often causing those with sudden onset anosmia a great deal of concern when all food suddenly loses its flavor. Congenital anosmics often have a much more developed sense of taste than those who could smell at some point in their lives, and can enjoy food just as much as someone who could smell.

Presentation

 * Anosmia can have a number of detrimental effects. Patients with sudden onset anosmia may find food less appetizing, though congenital anosmics rarely complain about this. Loss of smell can also be dangerous because it hinders the detection of gas leaks, fire, body odor, and spoiled food. The common view of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.
 * Losing an established and sentimental smell memory (e.g. the smell of grass, of the grandparents' attic, of a particular book, of loved ones, or of oneself) has been known to cause feelings of depression.
 * Loss of olfaction may lead to the loss of libido, even to the point of impotency, which often preoccupies younger anosmic men.
 * Often people who have congenital anosmia report that they pretended to be able to smell as children because they thought that smelling was something that 'big people' could do, or did not understand the concept of smelling but did not want to appear different from others. When children get older, they often realize and report to their parents that they do not actually possess a sense of smell, much to the surprise of their parents.

History and Symptoms

 * Detailed history

Physical Examination

 * Complete physical including head and neck exam, and neurologic exam

Ear Nose and Throat

 * Anosmia can be diagnosed by doctors by using scratch-n-sniff odor tests or by using commonly available odors such as coffee, lemon, grape, vanilla and cinnamon.

Laboratory Findings

 * CBC (complete blood count)
 * Glucose
 * Blood urea nitrogen (BUN)/creatinine
 * LFTs (liver function tests)
 * Thyroid profile
 * Vitamin B12
 * ESR (erythrocyte sedimentation rate)
 * Blood toxicology
 * Urine toxicology
 * Antobody testing (Sjogren's)

Electrolyte and Biomarker Studies

 * Electrolytes

MRI and CT

 * MRI and head CT if indicated

Other Diagnostic Studies

 * Allergy testing
 * Nasal discharge testing

Treatment

 * No cure for permanent anosmia
 * Treat underlying disease (in hopes of treating anosmia due to CNS or endocrine diseases)

Acute Pharmacotherapies

 * Temporary anosmia:
 * Corticosteroids
 * Antibiotics
 * Antihistamines
 * Decongestants

Chronic Pharmacotherapies

 * Supplemental vitamins for patients with vitamin deficiencies

Surgery and Device Based Therapy

 * Polypectomy and sinus surgery

Indications for Surgery

 * Initial therapy for temporary anosmia is ineffective.