Allergic Rhinitis

References Allergic rhinitis management pocket reference 2008. Allergy 2008: 63: 990–996. Pharmacotherapy: A pathophysiologic Approach. 7th Edition 2008. Safety of Antihistamines in Children. Drug Safety 2001; 24 (2): 119-147. Second-Generation Antihistamines Actions and Efficacy in the Management of Allergic Disorders. Drugs 2005; 65 (3): 341-384

allergic rhinitis <immunology> An inflammatory response in the nasal passages to an allergic stimulus. Often includes: nasal congestion, sneezing, runny or itchy nose

Allergic Rhinitis The most common atopic disease The hallmark of ~: a temporal relationship between the exposure to allergens & the development of nasal symptoms It takes at least 2 years of exposure to aeroallergens (airborne environmental allergens) to develop AR (thus, very rare in children <1 year) The prevalence of AR: lowest in children < 5 yrs highest 2nd---- 4th decades Genetic predisposition (60%)

In a sensitized individual, allergic rhinitis occurs when mucous membranes are exposed to inhaled allergenic materials that elicit a specific response mediated by immunoglobulin E (IgE).

Allergen sensitization and the allergic response. A. Exposure to antigen stimulates IgE production and sensitization of mast cells with antigen specific IgE antibodies. B. Subsequent exposure to the same antigen produces an allergic reaction when mast cell mediators are released.

Mast cells degranulating and releasing vasoactive amines. Mast cells release a variety of preformed (histamine, heparin, tryptase, chymotryptase and carboxypeptidase) and newly synthesized lipid (LTB4, LTC4, PGD2 and platelet activating factor) and cytokines. Mast cells degranulating and releasing vasoactive amines.

Classification AR is classified as seasonal or perennial Seasonal: repetitive and predictable symptoms (severe) Perennial: symptoms persist throughout the year without any obvious seasonal pattern WHO: replace terms with intermittent or persistent

Allergic Rhinitis Most patients develop symptoms before age 30 Asthma develops in about 19% of children with rhinitis (more likely with perrenial allergic rhinitis) The term “rhinitis” refers to the inflammation of the nasal mucous membranes. Whenever a a causative allergen can be identified allergic rhinitis It is difficult sometimes to distinguish between different types of rhinitis Comparison between different types of rhinitis

Features of Common Rhinitis Symptoms Allergic rhinitis Infectious rhinitis Vasomotor rhinitis Rhinitis Medicamentosa Etiology Allergen Viral or bacterial Unknown Tachyphylaxis to topical decongestants Symptoms Rhinorrhea, congestion, sneezing, pruritis, cough with postnasal drip ocular itching etc Fever (more common in children), mucupurulent rhinorrhea, scratchy throat, congestion, cough Rhinorrhea, congestion Congestion Pattern Perennial or seasonal Any time Temporal relationship with use of topical decongestant Associated Factors Concurrent atopic disease, family history None Affects women primarily, strong odours, alcohol, stress, change in humidity and temperature Overuse of topical decongestants, concurrent use of antihypertensive therapy

Perennial Allergic Rhinitis 1 Caused by continuous exposure to many different types of allergens Dust Mite the most common cause of perennial allergic rhinitis Commonly: household dust mites, molds, cockroaches, house pets Less commonly: cottonseed & flaxseed (found in fertilizers, hair setting preparations and foods); some vegetable gums (found in hair setting prep & foods)

Caused by: Dust mites

Perennial Allergic Rhinitis 2 Dust mite: thrive in carpets, beddings & reproduce best in warm (18-21ºC) humid (>50%) environment found in most homes Mites feed on human skin scales and their own faeces. Mite itself is not allergen, the main allergen is the glycoprotein that coats their faeces. Dust mite remain airborne for about 30 minutes after being disturbed Molds: grow best in warm, moist environment Cat-derived allergens: light small proteins secreted through the sebaceous glands in the skin. May remain airborne for up to 6 hrs. Can be detected at home even 6 months after removal of the cat. mites Any arthropod of the order acarina except the ticks. They are minute animals related to the spiders, usually having transparent or semitransparent bodies. They may be parasitic on man and domestic animals, producing various irritations of the skin (acariasis or mite infestations). Many mite species are important to human and veterinary medicine as both parasite and vector.

Seasonal Allergic Rhinitis Caused by wind-borne plant pollens (e.g. tree, grass. etc) “hay fever”, and “rose fever” are terms related to seasons associated grass pollinosis and NOT associated with FEVER! Symptoms of perennial allergic rhinitis are similar but less severe than those associated with seasonal AR Symptoms maybe associated with: (1) specific activities (e.g. vaccuming the carpet) (2) certain environments (e.g. cigarette smoke)

Complications Sinusitis Recurrent otitis media & hearing loss Patients who develop: fever, purulent nasal discharge, frequent HA, earache refer to Dr. for evaluation and treatment Chronic obstruction around the sinus ostia and eustachian tube increases the risk of sinusitis, recurrent otitis media and eustachian tube dysfunction

Symptoms of Allergic Rhinitis Ocular: itching, lacrimation, mild soreness, puffiness & conjuctival erythema Nasal: congestion, watery rhinorrhea, itching, sneezing, postnasal drip and nasal pruritus Head & Neck: loss of taste and smell, mild sore throat due to postnasal drip, earache, sinus HA, itching of the palate and throat Systemic: malaise & fatigue: malaise A vague feeling of bodily discomfort.

Physical Assessment “allergic shiners”  venous/lymphatic congestion Chronic mouth breathing highly arched palate A horizontal crease across the lower third of the nose (in patients repeatedly rub their noses upward) called “nasal salute” Nasal mucosa: pale & swollen Nasal secretions: clear & watery Eyes: watery with scleral & conjuctival erythema and periorbital edema

Arched palate because of mouth breathing Allergic shiners Arched palate because of mouth breathing Periorbital edema

Uncomplicated allergic rhinitis does not cause fever, significant sore throat, vomiting or diarrhoea  these symptoms suggest viral or bacterial infection refer to doctor