Rhinitis
Terms
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- What is atopy?
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1. An inherited tendency to develop IgE-mediated allergic diseases such as rhinitis, asthma,and eczema
2. Male = female prevalence
3. No racial predilection
4. ? autosomal dominant inheritance with incomplete penetrance
5. Onset after 1-2 years of age; manifestations peak during childhood/early adult years - What is the "classic" allergic reaction?
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1. Exposure to known allergen
2. Immediate Response
- 5-30 min symptoms begin
- 30-120 min symptoms abate
- no inflammation
- lasts min- hours
3. Late response (hours later)
- no additional exposure
- symptoms and signs return
- Last several hours
- inflammatory component present
- lasts days to weeks - What are the 4 general features of Rhinitis?
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Four features
1. Sneezing, watery rhinorrhea, congestion, and pruritus (nasopharynx and eyes)
2. Onset within minutes after exposure to foreign substance (allergen, protein)
3. The same substance produces wheal/flare response within minutes of intradermal
injection
4. Symptoms may be very brief, persist throughout a season or show little or no variation with time - What are allergens?
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Allergy producing agents
Antigenic proteins inducing immune responses
Other constituents, in addition to antigenic proteins, play a role in allergy production
- Seasonal allergens
- Perennial allergens - What are some nasal functions?
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1. Olfaction
2. Resonation
3. Air conditioning: humidification, heating,
4. Filtration - What is the nasal physiology?
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1. Highly vascularized mucosa
-sympathetic->vasoconstriction
-parasym->dilation
2. Ciliary mucus transport
3. Local Ig production - What is the pathophysiology of allergic rhinitis?
- Allergen binds IgE armed mast cell or basophil-> mucosal mast cell degranulation-> mediator release->opening of tight intercellular tight junctions->enhanced penetration of Ag->further activation of mucosal mast cells and basophils->response multiplication
- What effects are produced by mediators?
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a. Increased mucus
b. Smooth muscle contraction
c. Vagal stimulation
d. Vasodilation
e. Chemoattraction
f. Neutrophil activation - What are the characteristics of an early response?
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1. Fast (mins to onset)
2. Humoral (histamine, heparin, tryptase, PGD2, LTC4)
3. Severity of symptoms and levels of mediators correlate closely
4. Symptoms decline as mediators decline
5. response lasts 30-180 min - What are the characteristics of a late response?
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1. occurs 4 or more hrs after original exposure
2. Additional mediator release
3. Slower (over several hours) for symptom resolution
4. Cellular infiltration of mucosa "primed mucosa"
5. Hyperreactivity
- Lower stimulus needed for response
- More vigorous response
- Non-specific "irritant" response - How does one diagnose allergic rhinitis?
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1. Appropriate symptoms
2. History of allergen exposure
3. Characteristic exam
- allergic "shiners"
- oral breathing
- nasal salute
- post nasal drip
- obstruction
4. Challenge testing
5. Mediator measurement - What is the treatment?
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Use stepwise approach
1. Avoidance
- pollen (close windows, AC)
2. Pharmacotherapy
- Antihistamines -> blocks histamine effects by competing for H1 Receptor
- Nasal/oral decongestants->
alpha adrenergic agonists (topical) or anti-cholinergics
3. Immunotherapy (use when other therapy fails b/c too toxic)
- good for pollens only