Allergic Rhinitis

Misc pollen[1]

Allergic rhinitis is an inflammation of the nasal membranes that presents with any of nasal congestion, itching, sneezing and rhinorrhea or a combination of any or all of them.


Presentation

  • Symptoms associated with this condition include pruritus of the nose or palate, rhinorrhea, sneezing, postnasal drip, nasal congestion, anosmia, headache, tearing, eye swelling, red eyes, earache, fatigue, drowsiness and a general feeling of malaise.
  • At presentation, history taking should also involve questions to determine trigger factors, familial history, and comorbid conditions.
  • Physical examination will reveal allergic shiners and nasal crease. The nasal turbinates may be enlarged and there may be erythema of the mucosa. The ears, eyes and neck as well as skin and lungs should be examined.

Workup

  • An allergy skin test should be done to check for the immediate hypersensitivity reaction to specific allergens. A limited number of allergens should be used. The total serum IgE could be increased as well as the total blood eosinophil count.
  • Imaging studies like plain radiograph will help to exclude structural abnormalities as well as detect comorbid conditions. CT scan of the sinuses can help in evaluation sinusitis, whether acute or chronic. MRI is useful for checking the soft tissues for features of malignancy.
  • A nasal smear could also be done and may show eosinophilia [7].

Treatment

The treatment of allergic rhinitis is three pronged.

  • The first is environmental control and avoiding allergens which can be achieved by reducing outdoor exposure, regular washing of bed linens, and avoiding animals [8]. 
  • Second is medications and they include antihistamines, leukotriene receptor antagonists, nasal corticosteroids, and decongestant.
  • The third is immunotherapy which is considered in severe diseases or when there is a poor response to other management options [9].

Prognosis

The long term prognosis of allergic rhinitis, if it occurs alone, is good if it has developed early in childhood as symptoms tend to diminish as one gets older. When people with allergic rhinitis have other coexisting disorders, e.g. asthma, the morbidity is increased and mortality is seen in some cases. Although the condition is not considered severe, it causes enough discomfort to interfere with normal daily function.

Etiology

The pollen responsible for causing haying fever varies from region to region and individual to individual. It is mostly caused by the pollens of wind pollinated plants and examples of these plants include pine, alder, birch, hazel, willow, poplar, plane, lime and olive. It could also result from exposure to grass pollens from grasses like timothy and ryegrass. Weeds that may induce an allergic reaction are plantain, ragweed and mugwort [2]. Allergic rhinitis can also be caused by spores of outdoor molds like apsergillus and penicillin and by house dust mites, furry household pets, cockroaches and rodents [3].

Some people develop a reaction when they are exposed to certain fragrances, especially ones containing Balsam of Peru.

Epidemiology

There is a cumulative prevalence rate of 20% in the United States with as much as 40 million people suffering from this disease. In the international community, the prevalence varies among countries, largely due to their different geographies and availability and potency of allergens.

Morbidity and mortality from allergic rhinitis on its own is insignificant. The condition however occurs concurrently with other conditions like asthma and otitis media which may cause significant morbidity and even mortality.

Most cases develop by age 20 years but it may develop far earlier. In children, it affects more males than females but the ratio evens out in adulthood. It affects people of all races and has no predilection for a particular race [4].

Sex distribution
Age distribution

Pathophysiology

  • It primarily involves inflammation of the mucous membrane of the nose. Other organs may be affected in certain individuals like the eye, ear and pharynx. Inflammation is triggered by an immunoglobulin E (Ig E) response to an extrinsic protein which brings about a complex interaction of inflammatory mediators.
  • The tendency to develop this reactions to allergens has a genetic component. When susceptible individuals are are exposed to certain allergens, there is sensitization. This sensitization is characterized by production of specific IgE to act against these allergens. This IgE are present in the surface of mast cells which are seen in the mucosa of the nose. When the allergen, like a pollen, is inhaled, it binds to the IgE on the surface of the mast cells and causes immediate or delayed release of inflammatory mediators like histamine and kinins. The mast cells then synthesize other mediators like prostaglandins and leukotrienes. These mediators, following some complex interactions will cause the symptoms that are seen in allergic rhinitis [5].
  • Stimulation of mucus glands will lead to increased secretions and increased vascular permeability will lead to plasma exudation. The will be congestion due to vasodilation, pruritus from stimulation of sensory nerves and these events can occur in minutes that’s why it is called immediate inflammatory reactions.
  • These mediators then, through a complex interplay, will lead to recruitment of the delayed inflammatory mediators like neutrophils and lymphocytes to the nasal mucosa. This takes up to 8 hours to occur and may last for days and are called the late inflammatory reaction [6].

Prevention

Prevention involves reduction of exposure to known allergens as much as possible and regular use of drugs [10].

Summary

Allergic rhinitis is popularly called "Hay fever". This is because it is triggered by some precise seasonal plants that are mostly prevalent during the haying season. It is however possible to suffer from this condition throughout the year, haying season or not [1].

Patient Information

  • Definition: Allergic rhinitis is an inflammation of the nasal mucosa caused by the response of a hyperactive immune system.
  • Cause: It is mainly caused by pollens from plants, flowers, grasses and weed, but can also be caused by exposure to outdoor molds, as well as house dust mites, rodents, cockroaches and household pets like dogs and cats. Some of these allergens are used to make fragrances and allergic reactions to perfumes have been reported.
  • Symptom: This will present with symptoms like, itchy nose, runny nose, postnasal drip, and nasal congestion. Other symptoms are headache, earache, red eyes, itchy eyes, drowsiness, fatigue and a general feeling of unwell.
  • Diagnosis: This is done with the help of certain tests to check what causes the allergic reaction. Laboratory investigations are also done to check the levels of some inflammatory mediators as well as imaging like X-rays and CT scan to examine the surrounding structures and rule out complications.
  • Treatment: This involves avoiding the allergen when it has been detected, using drugs to control the hyperactive immune system and immunotherapy.

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References

  1. Thompson AK, Juniper E, Meltzer EO. Quality of life in patients with allergic rhinitis. Ann Allergy Asthma Immunol. Nov 2000;85(5):338-47; quiz 347-8.
  2. Matheson MC, Dharmage SC, Abramson MJ, et al. Early-life risk factors and incidence of rhinitis: results from the European Community Respiratory Health Study--an international population-based cohort study. J Allergy Clin Immunol 2011; 128:816.
  3. D'Alonzo GE Jr. Scope and impact of allergic rhinitis. J Am Osteopath Assoc 2002; 102:S2.
  4. Settipane RA. Demographics and epidemiology of allergic and nonallergic rhinitis. Allergy Asthma Proc 2001; 22:185.
  5. Skoner DP. Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis. J Allergy Clin Immunol. Jul 2001;108(1 Suppl):S2-8
  6. Hansen I, Klimek L, Mosges R, Hormann K. Mediators of inflammation in the early and the late phase of allergic rhinitis. Curr Opin Allergy Clin Immunol. Jun 2004;4(3):159-63.
  7. Wallace DV, Dykewicz MS, Bernstein DI, et al. The diagnosis and management of rhinitis: an updated practice parameter. J Allergy Clin Immunol 2008; 122:S1.
  8. Platts-Mills TA. Allergen avoidance. J Allergy Clin Immunol. Mar 2004;113(3):388-91.
  9. Weber RW. Immunotherapy with allergens. JAMA. Dec 10 1997;278(22):1881-7.
  10. Hadley JA. Evaluation and management of allergic rhinitis. Med Clin North Am. Jan 1999;83(1):13-25.

Media References

  1. Misc pollen, Public Domain

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