Allergic Rhinitis Overview

Allergic Rhinitis Overview

• Allergic rhinitis is a common inflammatory condition of the nasal mucosa.
• It presents with symptoms like sneezing, nasal congestion, clear rhinorrhea, and itching.
• It's an IgE-mediated immune response triggered by inhaled antigens.
• Allergic rhinitis can be seasonal (20%), perennial (40%) or a mix of both (40%).

Allergens

• Outdoor: Pollen from trees, weeds, plants, and grasses; fungal spores and molds.
• Indoor: Animal dander (cats, dogs, mice), dust mites (major allergen in house dust, bedding, furniture), and insects (cockroaches).

Common Allergens

• Inhaled: Pollen, fungal spores/molds (Penicillium), insects (cockroaches, house), animals (cats, dogs, rats), dust mites (Dermatophagoides).
• Ingested: Nuts, fish, eggs, milk. (Not always inhaled or ingested.)

Allergic Rhinitis and Asthma

• Allergic rhinitis and asthma frequently co-exist.
• A substantial link is suggested between the two conditions:
• 74-81% of asthmatics exhibit allergic rhinitis
• 40% of those with rhinitis also suffer from asthma

Risk Factors

• Genetic predisposition: Genetic susceptibility to developing allergies.
• Age and sex: Onset often happens at puberty, and may increase during pregnancy.
• Environmental factors: Pollution can increase nasal responsiveness to environmental allergens.
• Irritants: Tobacco smoke, diesel exhaust, mosquito repellents, and perfumes

Classification of Allergic Rhinitis (ARIA)

• Intermittent: Symptoms less than 4 days a week or 4 weeks a year.
  • Sub-type: Mild – Normal sleep, no impairment of daily activities, normal work and school.
• Persistent: Symptoms 4 or more days a week and 4 or more weeks a year..
  • Sub-type: Moderate/Severe – Abnormal sleep, impairment of daily activities, sport, leisure, and work and/or school.

Pathophysiology of Allergic Rhinitis

• Phase 1 (Sensitization): Allergen exposure, antigen-presenting cells process the allergen, leading to presentation to T cells. Subsequently, B cells differentiate into plasma cells, producing antibodies against the allergen (IgE).

• Phase 2 (Clinical disease): Subsequent exposure to allergen results in mast cell degranulation releasing histamine and other mediators leading to nasal symptoms.

Clinical Presentation

• Nasal symptoms: Itching, rhinorrhea (watery discharge), nasal congestion, sneezing.
• Associated symptoms: Ocular itching and tearing, eye redness, throat itching and coughing, ear itching and pain, anosmia (loss of smell) or taste disturbances, mouth breathing, malocclusion, snoring, fatigue, drowsiness, and malaise.
• Systemic symptoms: Weakness, discomfort or uneasiness, irritability, fatigue, difficulty concentrating, decreased appetite.

Signs of Allergic Rhinitis

• Nasal signs: Allergic salute (rubbing the tip of the nose), nasal crease.
• Facial signs: Dennie-Morgan Creases (double skin folds in lower eyelid skin), allergic shiners.
• Ocular signs: Edema of the lids, congested conjunctiva (cobble stone appearance), increased lacrimation.
• Otologic signs: Higher levels of IgE in the middle ear. E-tube dysfunction.
• Pharyngeal signs: Cobblestone appearance of posterior pharyngeal wall.

Diagnosis

• History: Medical history of symptoms, exposure to allergens.
• Physical exam: Visual assessment of nasal anatomy, looking for signs of allergic rhinitis.
• Allergy diagnosis: Skin prick test (rapid, efficient; contains multiple allergens like pollen, mold, dust mites, animal dander), total IgE, specific IgE, nasal smear (for eosinophils), nasal challenges, and nasal endoscopy.

Treatment

• Allergen avoidance: Managing exposure to known allergens - critical.
• Pharmacotherapy: Antihistamines (oral & topical), topical corticosteroids, chromones, and decongestants.
• Immunotherapy: Specialist treatment can change the natural progression of the disease.
• Patient education: Crucial for symptom management and control.

Avoidance of Triggers

• Remove pet animals from bedroom.
• Wash pets weekly.
• Remove carpeting, furry or feathered pets.
• Maintain heating and cooling systems and control indoor humidity (55-73%).
• Avoid smoking

Controlling Dust Mites

• Dust mites are microscopic organisms that live in dust, often in humidity and warmth.
• They feed on dead skin scales.
• Growth factors include food sources, temperature (warmth), and high humidity.
• Strategies include removal from reservoirs (carpets, mattresses, pillows), vacuuming, and washing bedding with hot water and protein denaturing agents.

Comorbidities

• Allergic rhinitis is closely related to various conditions such as asthma, upper respiratory infections and more.

Differential Diagnosis

Consider other conditions that mimic allergic rhinitis, like vasomotor rhinitis (non-allergic nasal inflammation), rhinitis medicamentosa (drug-induced rhinitis), hormonal rhinits, atrophic rhinitis, environmental, infectious, and gustatory rhinitis.

Surgery

• Typically not the first or best choice
• Considered in cases of co-existing conditions that complicate or worsen allergic rhinitis. (eg., nasal obstruction refractory to medication).
• Options: Functional endoscopic sinus surgery, turbinoplasty and more.

Key Points

• Allergic rhinitis is common.
• A thorough history, physical examination, and laboratory investigations are crucial.
• Managing environmental control, pharmacotherapy, and adequate patient counseling are essential.