Allergic rhinitis is defined as inflammation of the nasal mucosa as a result of an exposure to an allergen in the air or less commonly, food and is characterized by a symptom complex that consists of any combination of the following:
It is a common condition, affecting over 20% of the population. Allergic rhinitis involves inflammation of the mucous membranes of the nose, eyes, eustachian tubes, middle ear, sinuses, and pharynx.
Allergic rhinitis can be associated with a number of co-morbid conditions, including asthma, atopic dermatitis, and nasal polyps. 80% of asthmatic have allergic rhinitis.
Allergic rhinitis is divided into 2 main types:
Patients with intermittent disease have symptoms for less than 4 days/week and less than 4 weeks/year, whereas patients with persistent disease have symptoms for more than 4 days/week for more than 4 weeks/year.
The complications of allergic rhinitis include
Symptoms and signs of allergic rhinitis include rhinorrhea (runny nose), nasal congestion, sneezing, nose itching, redness, tearing, swelling, ear pressure, and postnasal drip. Most patients also have watery and itchy eyes. The mucosa of the nasal turbinates may be swollen. With the swollen turbinates, the nasal passage is narrowed, resulting in difficulty breathing and nasal congestion.
Precipitating factors of the allergic rhinitis include pollens, molds, dust mites, cats, dogs, cockroaches. In Singapore the most common allergen is house dust mite. These are aeroallergens that when inhaled into the nose will land on the nasal mucosa and bind with the immunoglobulin E and set off a cascade of chemically mediated allergic response. These allergens both inhaled and ingested can be tested and assessed in patients.
Allergy testing is used for testing reaction to specific allergens which can be helpful to confirm the diagnosis of allergic rhinitis and to determine specific allergic triggers. The methods of determining allergy to a particular substance are allergy skin testing (testing for immediate hypersensitivity reactions) and in vitro (blood test sent to the laboratory) diagnostic tests, such as the radioallergosorbent test (RAST), which indirectly measures the quantity of specific IgE to a particular antigen.
Management of nasal allergies, according to the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, consists of 4 major categories of treatment:
Use of environmental controls is not adequately explored in most patients. For most patients, the removal of the trigger can have a dramatic effect. The difficulty arises when the trigger needs to be identified and eliminated. Eliminating the trigger may be simple if removal of a feather pillow or blanket is involved; however, it can be very difficult if a family pet needs to be removed. To reduce dust mites, special allergen-proof covers for pillows and mattresses may be obtained. The important factor is that the covers must be plastic on one side and have a zippered closure. The pillow must be covered, which is more crucial than covering the bed mattress itself because the pillow is where the patient’s head usually spends most of the night.
Most cases of allergic rhinitis respond to pharmacotherapy. Patients with intermittent symptoms (see ARIA guidelines above) are often treated adequately with oral antihistamines, decongestants, or both as needed. Regular use of an intranasal steroid spray may be more appropriate for patients with chronic persistent symptoms.
Surgical treatment for allergic rhinitis is mainly indicated for patients who have tried medication. This involves mainly reduction of the size of the inferior turbinates and/or correction of the nasal septal deviation. Various techniques are available. Surgery is also indicated for complicating conditions, such as chronic sinusitis, severe nasal septal deviation (causing severe obstruction), nasal polyps, or other anatomical abnormalities.
Immunotherapy (desensitization) is the use of gradual exposure of low dose allergens to the patient (either through skin injections or sublingual treatments, below the tongue). Success rates have been demonstrated to be as high as 80-90% for certain allergens. However, this is a long-term process; noticeable improvement is often not observed for 6-12 months, and, if helpful, therapy should be continued for 3 years.