Allergic Rhinitis and Its Symptoms
Allergic Rhinitis
Essentials of Diagnosis
- Seasonal or perennial occurrence of nasal pruritus, congestion, rhinorrhea, or paroxysms of sneezing, which may be associated with lower respiratory symptoms, eye erythema, pruritus, irritation, tearing, or eczematous dermatitis.
- Environmental aeroallergen exposure.
- Presence of specific-IgE antibody to tested aeroallergens.
Clinical Findings
In addition to the symptoms listed above, up to 40% of
patients with allergic rhinitis also manifest lower respiratory symptoms: cough,
wheezing, chest tightness, or dyspnea. The physical examination may reveal
edematous or inflamed nasal mucosa. In severe cases, the affected mucosa may be
pale, boggy, or blue-tinged from vascular engorgement and venous congestion.
Nasal symptoms can be nonspecific, however, and the differential diagnosis can
include viral rhinitis, bacterial sinusitis, vasomotor rhinitis, nasal
polyposis, drug-induced rhinitis, hormonal rhinitis, rhinitis medicamentosa,
atrophic rhinitis, gastroesophageal reflux, and systemic disorders such as
thyroid disease or Wegener's granulomatosis. Even a basic understanding of
regional aeroallergen patterns and seasons can aid the clinician during the
evaluation of patients presenting with acute or chronic rhinitis.
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| Allergic Rhinitis |
Patients with moderate to severe disease, those who are
potential candidates for allergen immunotherapy, and those with strong
predisposing factors for atopic diatheses (eg, a strong family history of atopy
or ongoing exposure to potential sources of allergen) should undergo testing.
Since the development of rhinitis precedes the presentation of asthma in over
50% of cases, early intervention may decrease the risk of more severe clinical
allergic disease. Patients with comorbidities or associated complications such
as allergic asthma, allergic conjunctivitis, chronic cough, sinusitis,
polyposis, eczema, or otitis media may also benefit from evaluation by a
subspecialist.
Treatment
The three basic principles of allergy management are
avoidance of the allergen, symptomatic pharmacologic therapy, and specific
allergen immunotherapy. Patients with suboptimal responses to reasonable
therapeutic interventions benefit from diagnostic allergy skin testing.
Avoidance Therapy
Avoidance is the most effective treatment for any allergic
condition but may be limited in its applicability. It cures the clinical
manifestations but does not reduce the sensitivity to the allergen.
Pollens
Airborne allergens can travel significant distances, but
concentrations are highest near their source. Pollen release occurs in the early
morning, and airborne levels depend on temperature and wind velocity. Closing
windows and remaining in air-conditioned environments can decrease exposure when
pollen counts are high.
Animal danders
If the allergy is slight, the patient may benefit from
merely keeping the animal out of the bedroom; usually, however, it is necessary
to remove the animal from the home altogether. Hypersensitivity to animal dander
can be exquisite, and passively transferred dander can accumulate to significant
levels in "off-limits" areas. Washing or otherwise treating the fur of a live
animal has not been proved to reduce allergenicity.
House dust and dust mites
The mattress and pillows should be encased in dust
mite-proof material, and all other bedding should be washed weekly and dried at
high temperature. The bedroom floor should be uncarpeted. The room should be
dusted frequently. Electronic air purifiers are of unproved effectiveness for
dust mite reduction since the primary source of exposure is the bed. Acaricides
are not recommended. Dust mite reduction interventions can be successful
adjunctive measures to medical therapy, can significantly reduce symptoms, and
can reduce bronchial hyperreactivity and medication requirements in sensitized
patients.
Mold spores
Out of doors, mold spores are unavoidable during certain
seasons. Nevertheless, activities such as gardening and farming can be
associated with acute high levels of exposure and should be avoided. Indoor mold
contamination can be controlled by repairing leaks, by preventing mold buildup
in bathrooms and around windows, and by replacement of mold-contaminated
carpeting.
Drug Therapy
Three classes of pharmacotherapy are useful for
IgE-mediated diseases, based on (1) inhibition of release of mediators from mast
cells, (2) inhibition of the action of mediators on their target cells, and (3)
reversal of the vascular and inflammatory responses in the target tissues
Antihistamines
Antihistamine drugs competitively inhibit the binding of
histamine to H1 receptors and are useful for the treatment of
IgE-mediated allergy. There are a number of such drugs, but the use of
first-generation antihistamines (chlorpheniramine, brompheniramine,
diphenhydramine, clemastine, hydroxyzine) are limited by sedation,
neurocognitive impairment, and dry mucous membranes. Rare complications include
seizures and tachyarrhythmias. Second-generation nonsedating histamine
H1-receptor-blocking drugs, loratadine, fexofenadine, and
desloratadine appear not to be associated with arrhythmias and, along with
cetirizine, are the systemic drugs of choice. Cetirizine is mildly sedating, but
the incidence of side effects is markedly lower than that of its parent
compound, hydroxyzine. Azelastine is a topical antihistamine preparation that is
applied intranasally to decrease its systemic side effects. Because of
methodologic issues, publication bias, and inability to generalize findings,
providing a rank order of potency and clinical efficacy for the available
antihistamines is difficult. Clinical tolerance or tachyphylaxis does not occur
at prescribed dosages but an incomplete response to antihistamine therapy often
indicates the need for combined treatment with a corticosteroid nasal spray.
This highlights the necessity to control both the early phase and late phase of
the allergic response for optimal symptom control.
Antihistamine therapy only rarely alleviates symptoms of
asthma, although it is not contraindicated when used to treat concomitant
rhinitis or pruritus. The antipruritic effect of antihistamines may be a useful
adjunct in treatment of eczematous diseases.
Sympathomimetic drugs
Adrenergic agonists are used for both -adrenergic
(vasoconstricting) and -adrenergic
(bronchodilating) properties. -Adrenergic agonists can
be used orally (pseudoephedrine, phenylephrine) or topically (phenylephrine,
naphazoline, oxymetazoline) as nasal decongestants and topically as conjunctival
vasoconstrictors. Daily use of topical preparations can lead to rapid
development of rebound vasodilation (rhinitis medicamentosa). The main side
effects of oral decongestants are insomnia, tremor, and tachycardia.
Corticosteroids
These drugs have a therapeutic role in virtually all types
of allergic diseases because of their anti-inflammatory action rather than by
their immunosuppressive effects. Systemic use for the treatment of allergic
disease, however, requires close attention to toxicity. Corticosteroids are
available in oral, intramuscular, intravenous, intranasal, and bronchial
inhalation forms; as eye drops; and in topical formulations for dermatologic
use. Short-term systemic burst therapy can be used for treatment of severe
asthma, marked allergic rhinitis, allergic fungal sinusitis, and allergic
bronchopulmonary aspergillosis. Because of complications, including cataracts,
corneal ulceration, keratitis, and glaucoma, the prescription of corticosteroid
eye drops should be reserved for ophthalmologists.
Topical corticosteroid nasal sprays are effective and
appear safe for long-term use, but epistaxis can occur and nasal septum
perforation is a rare complication. Although the dosages and formulations
available for the treatment of asthma vary greatly in terms of dosage and
clinical potency, intranasal preparations of flunisolide, fluticasone,
beclomethasone, mometasone, budesonide, and triamcinolone are similarly
efficacious for the treatment of allergic rhinitis. Long-term topical
corticosteroid therapy for allergic rhinitis is an essential aspect of
management of the inflammatory phase of the disease. It may take several days of
consistent use before optimal responses are seen, but these compounds have
consistently proved superior to antihistamine monotherapy for control of nasal
pruritus, sneezing, and nasal congestion. Surprisingly, they may also provide
some relief from concomitant eye pruritus and have shown positive effects on
sleep, which can be adversely affected in patients with allergic rhinitis.
Topical corticosteroids may also be effective for treatment of vasomotor
rhinitis and may be used as adjunctive treatment for sinusitis in combination
with antibiotic therapy.
Cromolyn sodium and sodium nedocromil
Pretreatment with these drugs prevents the response to
allergen by stabilizing the mast cell, although the specific molecular
mechanisms of action are unknown. Although unrelated, they have similar effects
and, because of poor bioavailability, are effective only when applied directly
to the involved organ. Their action is short-lived, so that they must be given
three or four times a day. Cromolyn is available as a bronchial inhaler, nasal
spray, and ophthalmologic preparation; nedocromil is available in metered-dose
inhalers. In comparison with topical corticosteroids they appear to be much less
potent, but the drugs have very few side effects and wide margins of
safety.
Anticholinergic agents
Ipratropium bromide is effective as a nasal topical agent
for use in rhinitis. Mucous membrane glandular secretion is under cholinergic
control and can be inhibited by anticholinergic agents. First-generation
antihistamines have systemic anticholinergic activity, but ipratropium is
preferred as adjunctive treatment of allergic rhinitis or as primary treatment
for many types of nonallergic rhinitis. Ipratropium does not alleviate sneezing,
pruritus, or nasal congestion but can be useful for treatment of postnasal drip
and rhinorrhea.
Leukotriene antagonists
Montelukast is an effective drug for the treatment of
asthma. To a much more limited degree, leukotriene antagonists can be
efficacious for the treatment of allergic rhinitis, either as monotherapy or
combined with an antihistamine. By inhibiting leukotriene-mediated vasodilation
vascular permeability and by potentially reducing eosinophilic inflammation,
orally administered montelukast can provide symptomatic relief, especially for
nasal congestion. It is less effective than intranasal corticosteroids,
however.
Nasal saline irrigation
A variety of methods can be used to lavage the nasal
cavity. Nasal saline irrigation can improve mucociliary clearance, as well as
remove crusts, inspissated mucus, and accumulated secretions. Some studies have
shown improvement in chronic rhinosinusitis with hyperosmolar lavage but
isotonic normal saline (8 ounces lukewarm tap water mixed with salt (one-quarter
to one-half teaspoon), and a pinch of baking soda) seems preferred by many
patients. In cases where patients suffer from thick, tenacious nasal discharge,
saline irrigation prior to administration of topical agents may improve drug
delivery and efficacy.
Immunotherapy
Treatment of atopy—especially allergic rhinitis—by the
repeated long-term injection of allergen has been shown in many controlled
clinical trials to be an effective method for reducing or eliminating symptoms
and signs of the allergic disorder.
Indications
The severity and duration of a patient's symptoms should be
considered when selecting candidates for allergen immunotherapy. This treatment
is recommended for patients with severe allergic rhinoconjunctivitis who respond
poorly to drug therapy, those seeking to lower their long-term medication
requirements, and for those whose allergens are not avoidable. Immunotherapy is
unequivocally effective in patients with allergic rhinitis and allergic
conjunctivitis who react to pollens, mold, and house dust mites. It reduces
immunologic hypersensitivity, symptoms, and medication requirements. In children
with documented allergic rhinitis, immunotherapy may reduce the risk of
subsequent development of asthma. The efficacy of immunotherapy in allergic
asthma is still debated, but a meta-analysis of 20 randomized, controlled trials
done by Abramson showed a positive benefit in patients with allergic asthma. The
lower clinical response rates observed in asthma have been attributed to the
multifactorial nature of the disease. Immunotherapy is of no value in atopic
dermatitis.
Immunologic effects
"Allergen immunotherapy" is preferable to "desensitization"
because the immunologic basis for this treatment has not been clearly
elucidated. Nevertheless, certain immunologic changes can be induced by these
injections. Circulating levels of IgE antibodies specific to the injected
allergens increase slightly during the first few months, then decrease,
eventually to substantially lower levels than before treatment. Seasonal rises
in IgE antibodies to pollens are blunted or eliminated. IgG blocking antibody is
produced. Changes in regulatory T cells favoring suppression of IgE antibody
production and apoptosis of antigen-specific T cell clones have been noted.
TH2 cytokine responses may be shifted toward TH1
responses in peripheral blood mononuclear cells. Higher thresholds for release
of inflammatory mediators and decreases in late-phase allergic reactions might
also be related to the reduction in biologic sensitivity of end-organ systems
(eyes, nose, bronchi, and skin).
Clinical effects
Most patients with allergic rhinitis caused by
aeroallergens become more tolerant to natural pollen exposure during successive
seasons while receiving immunotherapy. A small minority becomes completely
asymptomatic, but most patients enjoy a significant decrease in symptoms and
medication usage. Only high-dose injected immunotherapy has been demonstrated to
be effective. A beneficial response may persist for years after treatment is
stopped. The clinical effects and immunologic responses are antigen-specific,
but the treatment may also decrease the risk of developing new environmental
sensitivities.
Procedure
A sterile aqueous solution of the allergen or allergens
responsible for the patient's disease is administered by subcutaneous injection
in increasing doses once or twice a week until a maintenance dose is reached, at
which time the interval is advanced to every 4 weeks. The maintenance dose is
typically one to ten thousand times the starting dose. Ascending doses are used
to minimize the risk of systemic allergic reactions during initial stages of
immunotherapy. Three to 5 years is a typical course of therapy. Oral
immunotherapy remains experimental in the United States, and sublingual or
low-dose immunotherapy is unconventional and of unproved efficacy.
Adverse effects
Reactions to treatment may be local or systemic. Localized
immediate and late-phase skin reactions occur at injection sites. These are not
harmful, but the dose must be adjusted to avoid excessively large or prolonged
local reactions. Immediate systemic reactions or anaphylaxis is a potential
problem with each injection and must be prevented by monitoring of dosage. The
patient remains at the treatment facility for at least 20 minutes after each
injection so that drugs and equipment for treating anaphylaxis will be available
if needed. No long-term adverse consequences of aqueous allergen extract
immunotherapy are known to have occurred in immunocompetent individuals.
Recources Info
Current Medical Diagnosis & Treatment 2008
Stephen J. McPhee, Maxine A. Papadakis, and Lawrence M. Tierney, Jr., Eds. Ralph Gonzales, Roni Zeiger, Online Eds.
Current Medical Diagnosis & Treatment 2008
Stephen J. McPhee, Maxine A. Papadakis, and Lawrence M. Tierney, Jr., Eds. Ralph Gonzales, Roni Zeiger, Online Eds.