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ALLERGIC RHINITIS. Dr Gary Kroukamp. ALLERGIC RHINITIS. IgE-Mediated Type 1 hypersensitivity reaction. In the mucous membranes of the nasal airways (closely linked to allergy affecting rest of URT). Allergic Rhinitis. Affects 30% of population Can be: seasonal
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ALLERGIC RHINITIS Dr Gary Kroukamp
ALLERGIC RHINITIS IgE-Mediated Type 1 hypersensitivity reaction
In the mucous membranes of the nasal airways (closely linked to allergy affecting rest of URT)
Allergic Rhinitis • Affects 30% of population • Can be: seasonal perennial (with or without seasonal exacerbations)
Aetiology • Allergens: soluble proteins or glycoproteins pollens moulds house dust mite animal epithelia
Pathogenesis • Allergen interacts with cell-bound IgE • Triggers chain of events which causes release of prostaglandin D, leukotrines & other chemotactic factors, causing • Mast cell disruption – histamine, proteases • Capillaries more permeable • Eosinophil infiltration • Oedema
Typical features • Vascular congestion • Oedema • Rhinorrhoea • Irritation - sneezing
Clinically • Seasonal - early summer to autumn, depending on allergen • Rhinorrhoea, nasal irritation, sneezing + itchy and watering eyes • Family history of atopy • Previous history of dermatitis or astma
Clinically • Perennial - may have seasonal exacerbations • Almost invariably house dust mite • Turbinate hypertrophy - nasal obstruction hyposmia
Clinically • Nasal mucosa - moist pale swollen (turbinate hypertrophy) Sometimes mucosa red and turbinates have blue tinge
Investigations • Skin tests - flexor aspect forearm - wheal and flare in 20 min • Negative control - carrier substance • Positive control - histamine (Resus equipment in case of anaphylaxis)
Investigations • Blood tests - PRIST (plasma radio-immunosorbent test) - RAST (radioallergosorbent test) Safer but expensive and no diagnostic superiority over skin tests
Investigations • Nasal smears - increased eosinophils - indicates allergy - not diagnostic
Investigations • Provocation tests - a drop of suspected allergen in nose causes symptoms
Management • Avoidance - of the allergen(s) - obviously helpful - not always practical
Management • Oral antihistamines - selectively block histamine receptors - now non-sedating - now once daily dose (intranasal antihistamine sprays now available)
Management • Topical steroid sprays - MAINSTAY of treatment - safe and effective - rarely cause crusting and bleeding - systemic absorption negligible - do not promote fungal ifections
Management • Depot IM steroids and Oral steroids - work!!! - reserved for when symptoms interfere with special events - weddings - examinations - etc.
Management • Topical anticholinergics - rhinorrhoea predominant • Sodium cromoglycate - mast cell stabiliser - 5 or 6 x daily - conjunctivitis benefits • Desensitisation - 1 or 2 allergens only - pollen usually - anaphylaxis risk
Management • Surgery - not for symptom control - turbinate surgery for sever obsruction
After-care • Most allergic rhinitis managed by GP • Advice on avoidance if allergen identified • Nasal abnormalties - nasal septal deviation - turbinate hypertrophy - sinus disease
After-care • Nasal abnormalties - nasal septal deviation - turbinate hypertrophy - sinus disease - may complicate and exaggerate symptoms - treated on their own merit