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Definition of Allergic Rhinitis
A symptomatic disorder of the nose resulting from an IgE-mediated immunological reaction following exposure to allergen.
The major symptoms are rhinorrhea, nasal itching, obstruction and sneezing which are reversible either spontaneously or with treatment.
Classification of Rhinitis
- Viral (e.g. common cold)
- Bacterial (often following a common cold)
- Intermittent (seasonal, e.g., hay fever)
- Persistent (perennial – continuous symptoms)
- Other medications
Caused by allergy or sensitivity to airborne agents in the workplace:
Related to puberty, pregnancy, menstrual cycle and some endocrine disorders
Other Causes/Types of Rhinitis
- Gastroesophageal reflux
- Atrophic rhinitis (shrunken nasal tissue)
- NARES: Non-Allergic Rhinitis with Eosinophilia
Cause not known
The traditional classification is seasonal and perennial, but in reality the situation is not as clearly defined. Allergens that are seasonal in one part of the world can be perennial in other areas. Typically patients are allergic to, and suffer symptoms from, more than one allergen.
A better classification is:
In which symptoms occur on less than 4 days a week or for less than 28 days at a time.
In which symptoms occur on the majority of days of the week and for more than 28 days.
The Severity of Allergic Rhinitis
In mild rhinitis there is no disturbance in sleep, leisure, school or work activities.
In moderate/severe rhinitis there is disturbance to sleep, leisure, school or work activities.
Epidemiology of Allergic Rhinitis
The prevalence of rhinitis symptoms in the International Study on Asthma and Allergies in Childhood (ISAAC) varied between 0.8% and 14.9% in 6-7 year olds and between 1.4% and 39.7% in 13-14 year olds. Countries with a very low prevalence include Indonesia, Albania, Romania, Georgia and Greece. Countries with a very high prevalence include Australia, New Zealand and the United Kingdom.
There is no equivalent to ISAAC for adults. National surveys show prevalence rates of rhinitis of between 5.9% (France) and 29% (United Kingdom) with a mean of 16%. Perennial (persistent) rhinitis is probably more common in adults than in children.
Immunopathology of Allergic Rhinitis
Allergic rhinitis is characterized by an inflammatory infiltrate in the nasal mucosa, which includes:
Chemotaxis, selective recruitment and transendothelial migration of eosinophils, mast cell precursors, macrophages, Langerhans cells and lymphocytes, particularly T helper cells.
Migration of cells, particularly mast cells, eosinophils, Langerhans cells and lymphocytes towards and into the epithelium. Activation, prolongation of survival of these cells with release of mediators.
Regulation of local and systemic IgE synthesis.
Allergen cross-links adjacent IgE molecules on the mast cell surface which triggers the release of mediators of hypersensitivity, including histamine, tryptase, prostaglandin D2 and leukotrienes.
Histamine, released from activated mast cells, is the major mediator of the early phase reaction following allergen exposure. It stimulates sensory nerves to cause sneezing and nasal itch, leads to vasodilatation, plasma exudation and stimulates mucous cells - together causing rhinorrhea - and plays some part in nasal obstruction. Histamine also has a pro-inflammatory role through up-regulation of adhesion molecules and release of cytokines.
Leukotrienes are generated and released into nasal tissue by mast cells, eosinophils, macrophages, neutrophils and epithelial cells. They play an important role in the late phase reaction causing nasal obstruction, mucus secretion and leading to inflammatory cell recruitment.
Diagnosis of Allergic Rhinitis
- Detailed allergic history and physical exam
- Nasal examination - anterior rhinoscopy
- Allergy tests - skin prick/puncture tests or measurement of specific IgE (RAST)
Additional Tests if Indicated
- Fiberoptic rhinoscopy - rigid or flexible
- Nasal secretions/scrape for cytology
- Nasal challenge with allergen
- C.T. scan
Rhinitis - Differential Diagnosis
- Deviated septum
- Adenoidal hypertrophy
- Foreign bodies
- Choanal atresia
- Wegener's granulomatosis
- Malignant – midline destructive granuloma
To read an in-depth review of allergic rhinitis and its diagnosis, click here
Management of Allergic Rhinitis
Allergen avoidance underlies all treatment.
Local (topical) administration of therapy is the preferred method of administration on the basis of an improved benefit:side effect ratio, but may be less patient acceptable and the therapeutic benefit is limited to nasal tissue.
National, continental and international guidelines for the treatment of allergic rhinitis with decongestants, antihistamines and corticosteriods have been published.
Further Reading on Allergic Rhinitis
To read an in-depth review on allergic rhinitis and its treatment, click here.
A global overview is available - click here.
Please click here to view and print a quick reference treatment algorithm chart from the World Allergy Organization's GLORIA program.