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ALLERGIC RHINITIS

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

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  1. ALLERGIC RHINITIS Dr Gary Kroukamp

  2. ALLERGIC RHINITIS IgE-Mediated Type 1 hypersensitivity reaction

  3. In the mucous membranes of the nasal airways (closely linked to allergy affecting rest of URT)

  4. Allergic Rhinitis • Affects 30% of population • Can be: seasonal perennial (with or without seasonal exacerbations)

  5. Aetiology • Allergens: soluble proteins or glycoproteins pollens moulds house dust mite animal epithelia

  6. 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

  7. Typical features • Vascular congestion • Oedema • Rhinorrhoea • Irritation - sneezing

  8. 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

  9. Clinically • Perennial - may have seasonal exacerbations • Almost invariably house dust mite • Turbinate hypertrophy - nasal obstruction hyposmia

  10. Clinically • Nasal mucosa - moist pale swollen (turbinate hypertrophy) Sometimes mucosa red and turbinates have blue tinge

  11. 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)

  12. Investigations • Blood tests - PRIST (plasma radio-immunosorbent test) - RAST (radioallergosorbent test) Safer but expensive and no diagnostic superiority over skin tests

  13. Investigations • Nasal smears - increased eosinophils - indicates allergy - not diagnostic

  14. Investigations • Provocation tests - a drop of suspected allergen in nose causes symptoms

  15. Management • Avoidance - of the allergen(s) - obviously helpful - not always practical

  16. Management • Oral antihistamines - selectively block histamine receptors - now non-sedating - now once daily dose (intranasal antihistamine sprays now available)

  17. Management • Topical steroid sprays - MAINSTAY of treatment - safe and effective - rarely cause crusting and bleeding - systemic absorption negligible - do not promote fungal ifections

  18. Management • Depot IM steroids and Oral steroids - work!!! - reserved for when symptoms interfere with special events - weddings - examinations - etc.

  19. 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

  20. Management • Surgery - not for symptom control - turbinate surgery for sever obsruction

  21. After-care • Most allergic rhinitis managed by GP • Advice on avoidance if allergen identified • Nasal abnormalties - nasal septal deviation - turbinate hypertrophy - sinus disease

  22. After-care • Nasal abnormalties - nasal septal deviation - turbinate hypertrophy - sinus disease - may complicate and exaggerate symptoms - treated on their own merit

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