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Allergic Rhinitis
ALTERNATIVE NAMES: Allergies, nasal allergies, allergic rhinosinusitis.
DEFINITION: Nasal inflammation caused by interaction of allergens with allergy cells within the lining of the nose.
WHAT IS GOING ON IN MY BODY? The nose has numerous important functions. It is an excellent humidifier and warmer of air destined for the lungs. This is largely accomplished by structures in the nose, such as turbinates. The lining inside the nose contains important components of the body's immune system. One part of the immune system is involved in immediate hypersensitivity reactions which result in allergies. The presence of allergies within an individual is largely genetically determined. In a susceptible person allergens that enter the nose, such as pollens, dust, dust mites, mold spores, and animal dander, interact with IgE antibody that is attached to cells inside the lining of the nose termed mast cells. When an allergen binds to the IgE on the mast cell, this causes discharge of a variety of compounds, such as histamine. Histamine causes a variety of other symptoms, such as sneezing, nasal congestion, and nasal discharge. Also released from the mast cell are a number of other potent inflammatory substances, some of which recruit another group of cells termed eosinophils into the nasal lining. The eosinophils migrate out of the blood vessels into the lining of the nose over approximately a 6 to 24 hour period. Once eosinophils arrive in the inflamed tissue, they release a number of potent inflammatory substances which can create additional symptoms hours after the original exposure. For example, an individual who is sensitive to cats when exposed to them will develop an immediate allergic reaction characterized by sneezing, eye itching, eye watering, itching in the nose and ears, nasal stuffiness, and drainage. This initial acute attack may continue as long as the individual is exposed. Once the person leaves the environment, then the allergy symptoms subside. These initial allergic symptoms are due to mast cell release. However, later that day, while the individual is away from the cat, another wave of allergic symptoms may occur, which are caused by eosinophils recruited into the tissue which then release their preformed inflammatory substances. Eosinophile in the nose are a helpful clue that allergic rhinitis is present.
Eosinophils are also responsible for the "priming" effect whereby delivering the same daily amount of allergen causes a gradual worsening of symptoms, heightened sensitivity to other agents that the patient would not normally respond to, and make the tissues more sensitive to non-allergic stimuli, e.g., particulates, dry air, fragrances, etc. The initial reaction in response to exposure to the allergen is termed the early reaction. The burst of symptoms occurring hours after the initial exposure is termed the late phase reaction.
WHAT ARE THE SIGNS AND SYMPTOMS? The symptoms of an acute allergic exposure inside the nose are sneezing, nasal stuffiness with subsequent difficulty breathing, clear watery nasal discharge, and nasal itching. There may be some other symptoms, such as a deep itching within the ear, cough, and itching, watering and redness of the eyes. Late phase reactions are very similar. The individual who has chronic allergy exposure may start to see other symptoms, such as more constant nasal stuffiness, a thicker, clear to white mucous secretion, diminished sense of smell, and sinus headaches which typically are in the forehead, cheek, and between the eyes. The individual with chronic allergies may also start to be affected by non-allergic stimuli, such as dry air, cold air, smoke, and particulates within the air.
WHAT ARE THE CAUSES AND RISKS? As mentioned above, the main cause of allergic rhinitis is interaction within the lining of the nose of cells involved in the allergic response and allergens, such as pollens, dust, dust mites, molds, and animal danders. The main risks of allergic disease is that it can predispose to sinus infections and asthma. Allergies exact a significant social cost in that billions of dollars per year of lost productivity occur because of allergic disease.
HOW TO PREVENT THE DISEASE: Unfortunately, since many allergens are airborne, other than changing the climate in which a person lives, it is very difficult for some to prevent allergic rhinitis. For those who may be exposed to cats or specific animals, it is important to not have them in the home. People who suffer from dust or dust mite allergies often benefit from having wood floors, plastic pillow and mattress covers, and moving to a more dry climate. One of the principles in allergic disease management is avoiding what an individual is allergic to. Since a component of it is genetic, picking one's parents would also be preventive! Antihistamines do not prevent the disease but only block the symptoms. Nasal Cromolyn helps to stop mast cells from releasing their substances but still do not prevent the allergen IgE interaction. Nasal steroids also do not stop the allergen from binding to mast cell IgE but do stop the mast cell from discharging and thus prevent early symptoms. However, the presence of topical nasal steroids prevents the late phase reaction.
HOW IS IT DIAGNOSED: A careful history and physical examination is important in diagnosing allergic rhinitis. Patients who suffer from it often present with the typical symptoms that are mentioned above. On physical examination, the eyes may appear to be bloodshot, and the nasal linings are often swollen with excessive amounts of clear nasal discharge. Development of symptoms after a specific exposure, such as being around cats, or an individual who suffers from similar symptoms during particular seasons, make the diagnosis rather easy to make. For those with more chronic, low-grade symptoms, such as nasal stuffiness, thick, clear nasal discharge, loss of smell, and chronic sinusitis, other tests can be performed, such as looking for eosinophils in the nasal mucus, or allergy testing to determine the diagnosis.
WHAT ARE THE LONG-TERM EFFECTS? For the patient who suffers from brief seasonal allergies, there are really very few long-term effects. Most of the long-term effects occur in those who have prolonged or frequent periods of allergic disease. The presence of allergic rhinitis increases the risk of asthma by four times. Chronic allergies, such as that seen with dust or dust mites and molds, or individuals with long stretches of allergic disease, such as spring through fall, are more likely to develop chronic long-term symptoms. These long-term symptoms include constant nasal congestion, excessive, thick nasal mucus, sinus headaches and facial discomfort, loss of sense of smell, chronic cough, and fatigue. With chronic nasal congestion, snoring and mouth-breathing may occur. Tissue damage and inflammation induced by eosinophils during late phase reactions are largely responsible for the chronic symptoms.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? The mainstay of allergy treatment is avoiding what an individual is allergic to. This is practical for those who have pet, dust, or dust mite allergies but is less practical for individuals who are sensitive to pollens and molds. For short-term allergic disease, oral antihistamines are very effective in controlling the symptoms of sneezing, eye watering and itching, nose and ear itching, and nasal discharge. Antihistamines generally do a poor job in diminishing the nasal stuffiness. Therefore, it is common to add a decongestant to an antihistamine preparation. For severe, acute exacerbations, oral steroids are very useful tools in that they potently block the allergic response.
For those with more prolonged allergic disease, the mainstay of management involves the use of nasal steroid sprays. These agents have been around for about 20 years, and as opposed to chronic oral steroid usage have an excellent safety profile. Compared to oral antihistamines, they are better in controlling acute symptoms and also have the advantage in that they block the late phase reaction in which most of the chronic tissue damage occurs. When an individual is on chronic nasal steroids to control their allergies, oral antihistamines can still be employed if the patient has allergic symptoms that develop while on topical steroid sprays. Instituting environmental controls, such as air filters and maintaining a clean environment are useful. Other treatments may be helpful, such as salt water nasal sprays and mucus thinners, such as Guaifenesin, which can help clear excessively thick nasal secretion. For the patient who has chronic or prolonged periods of allergic disease, or who is having complications from their allergies, such as sinus infections or asthma, or who is not responding well to medications, allergy shots become an important tool in management.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? Unfortunately, many of the over-the-counter antihistamines are plagued with sedation and decreased mental alertness as side effects. Individuals on the these antihistamines will often be excessively tired, and studies have clearly shown a decrease in mental function and impaired task performance. Examples of these antihistamines are Tavist®, Benadryl®, Chlor-Trimeton®, Dimetapp®, and Naldecon®. Some of the newer antihistamines have a much less risk of sedation and effects upon mental alertness. These have become the preferred agents of choice for oral antihistamine usage. (Such medications would include Claritin®, Zyrtec®, and Allegra®). Side effects using decongestants, such as Entex®, Sudafed®, Zephrex®, etc. include elevation of blood pressure, fast heart rate, anxiousness, and difficulty sleeping. Very few side effects occur with the use of saline sprays and Guaifenesin. The main side effects with the use of nasal steroids include nosebleeds, nasal crusting, and possibly a perforation, which is a hole that develops in the septum. The septum is a bone and cartilage wall that divides the nose into the two separate sides. There are a few acute side effects from oral steroids, such as appetite stimulation, irritability, excitability, sleeplessness, weight gain, and stomach irritation. Chronic steroid usage can be associated with loss of muscle mass, loss of bone mass, predisposition to infection, diabetes, poor wound healing, and cataracts. Side effects to allergy shots could include a severe allergic reaction (anaphylaxis), which is life-threatening, asthma attack, or a drop in cardiopulmonary function.
WHAT HAPPENS AFTER TREATMENT? With successful treatment of allergies both acute and chronic symptoms should improve.
HOW DO I MONITOR THE DISEASE? Monitoring the disease is mostly based on symptom control.
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