Alergic Rhinitis Flashcards
Allergic rhinitis
an IgE-mediated immunologic response of nasal mucosa to airborne allergens and is characterized by watery nasal discharge, nasal obstruction, sneezing and itching in the nose.
Two clinical types
Seasonal
Perennial
Seasonal Allergic Rhinitis
Symptoms appear in or around a particular season when the pollens of a particular plant, to which the patient is sensitive, are present in the air.
Perennial Allergic Rhinitis
Symptoms are present throughout the year.
AETIOLOGY
Inhalant allergens
Genetic predisposition
Seasonal allergens
pollens from trees, grasses and weeds.
Perennial allergens
molds, dust mites, cockroaches and dander from animals. Dust includes dust mite, insect parts, fibres and animal dan- ders. Dust mites live on skin scales and other debris and are found in the beddings, mattresses, pillows, carpets and upholstery.
PATHOGENESIS
genetically predisposed individuals ➡️Inhaled allergens produce specific IgE antibody➡️ fixed to the blood basophils or tissue mast cells by its Fc end➡️ On subsequent exposure, antigen combines with IgE antibody at its Fab end ➡️degranulation of the mast cells ➡️release of several chemical mediators ➡️symptomatology of allergic disease ➡️vasodilation, mucosal oedema, infiltration with eosinophils, excessive secretion from nasal glands or smooth muscle contraction
priming affect
mucosa earlier sensitized to an allergen will react to smaller doses of subsequent specific allergen
Nonspecific nasal hyper-reactivity is seen in patients of allergic rhinitis why ?
Nasal mucosa gets “primed” to other nonspecific antigens to which patient was not exposed ➡️increased nasal response to normal stimuli resulting in sneezing, rhinorrhoea and nasal congestion
Clinically, allergic response occurs in
Acute or early phase
Late or delayed phase
Acute or early phase
within 5–30 min, after exposure to the specific allergen
consists of sneezing, rhinorrhoea nasal blockage and/or bronchospasm.
It is due to release of vasoactive amines like histamine.
Late or delayed phase
It occurs 2–8 h after exposure to allergen without additional exposure. It is due to infiltration of inflammatory cells—eosinophils, neutrophils, basophil, monocytes and CD4 + T cells at the site of antigen deposition causing swelling, congestion and thick secretion
In the event of repeated or continuous exposure to allergen
acute phase symptomatology over- laps the late phase.
Usually the onset is at
12–16 years of ag
Age group and sex predilection
There is no age or sex predilection
cardinal symptoms of seasonal nasal allergy
paroxysmal sneezing
nasal obstruction,
watery nasal discharge
and itching in the nose
par- oxysmal sneezing
10–20 sneezes at a time
Itching may also involve
eyes, palate or pharynx
Symptoms of perennial allergy
frequent colds, persistently stuffy nose, loss of sense of smell due to mucosal oedema, postnasal drip, chronic cough and hearing impairment due to eustachian tube blockage or fluid in the middle ear
Nasal signs
- transverse nasal crease
- pale and oedematous nasal mucosa which may appear bluish.
- Turbinates are swollen.
- Thin, watery or mucoid discharge is usually present.
transverse nasal crease produces a sign called
allergic salute
transverse nasal crease
a black line across the middle of dorsum of nose due to constant upward rubbing of nose simulating a salute
Ocular signs
oedema of lids, congestion and cobble- stone appearance of the conjunctiva, and dark circles under the eyes
allergic shiners
dark circles under the eyes