What we know about hayfever
The problem with allergies such as Hay fever and Allergic Rhinitis is that it is considered to be a trivial and inconsequential disease. Symptoms such as runny nose, itchy eyes and nose with sneezing and blockage are obviously not life threatening, but affect up to 25% of the population and are the cause of significant disability and cost to society. Patients may also experience fatigue, irritability, as well as mood, cognitive and sleep disturbance in addition to the nasal, ocular and throat symptoms. Allergic rhinitis has important co-morbid associations such as chronic sinusitis, glue ear, asthma exacerbations, nasal polyps, sleep apnoea and dental malocclusion.Chronic Allergic Rhinitis sufferers often have typical facial features called the "allergy face". Nasal blockage and sinus congestion predispose to the bluish discolouration of the lower eyelids called "allergic shiners", the characteristic linear creases under the eyelid are referred to as "Dennes lines". Constant nasal rubbing typifies the "allergic salute" and results in a prominent "nasal crease" across the nose. Continuous nasal blockage causes "nasal" speech and mouth breathing with disturbed sleep. This results in a high arched palate and the "long face syndrome" with dental crowding and malocclusion ("Buck teeth").
Allergic rhinitis may be either seasonal or perennial:
Seasonal allergic rhinitis is better known as "Hay fever".
Tree and grass pollens and some fungi trigger seasonal allergic rhino-conjunctivitis (nose and eye allergy) during Springtime and early Summer (March to June). Allergy sufferers experience intense nasal and eye itching with explosive sneezing, watery eyes and nose and itchy palate and ears with profuse post-nasal drip. These people do not develop the typical "allergy face" but have seasonal puffiness of the eyes and eyelids with associated nasal membrane swelling.Perennial allergic rhinitis or a "permanent cold".
Allergens such as house-dust mite droppings, cat and dog dandruff, horse hair, cockroach droppings and perhaps hamster or rabbit urine result in perennial allergic rhinitis with symptoms all year round. These patients are often misdiagnosed as having a "permanent" cold and receive inappropriate treatment with antibiotics. Their symptoms can be very subtle and include constant nasal blockage, snoring at night, watery post-nasal discharge, loss of taste and smell sensation and sneezing only on waking in the morning. Coexistent glue ear and chronic sinusitis with polyps (grape-like swellings inside the nose) are common.In 1999, the World Health Organisation introduced a new classification for Allergic Rhinitis (ARIA Guidelines). The purpose was to try and create similar treatment guidelines for asthma and allergic rhinitis which often co-exist in the same patient (80% of asthma sufferers have concomitant allergic rhinitis). Instead of the traditional seasonal and perennial divisions, they introduced Intermittent Allergic Rhinitis and Persistent Allergic Rhinitis. Intermittent would replace the Seasonal (Hay fever) type disease and Persistent would replace Perennial Rhinitis (but some overlap does take place). These two groups are then further sub-divided into Mild and Moderate/Severe symptoms and treated according to the new guidelines.
Allergic inflammation.
Allergic rhinitis occurs in "atopic" youngsters usually with raised blood levels of IgE antibodies to the common inhalant allergens such as house dust mites, tree and grass pollen, animal dander, cockroaches and mould spores. Occasionally foods such as milk and food additives can cause worsening symptoms. Children are sensitised in early life but may only manifest their allergy symptoms later in life. Perennial allergic rhinitis usually manifests before the age of 10 years, while seasonal allergic rhinitis occurs more commonly in teenagers and young adult males. Primary sensitisation results in the production of specific IgE antibodies, which later cross-link with allergens on mast cells in the nasal membranes releasing histamine and the allergy cascade. If the condition becomes more entrenched as occurs in chronic perennial rhinitis, then other inflammatory mediators and immune cells become involved.The allergy reaction in the nose involves a complex interaction between various inhalant allergens and immune cells. An allergen will link to specific IgE antibodies on mast cells near the nasal surface, resulting in histamine release. This is termed the Immediate Allergic Reaction. Other chemicals released by Mast cells include tryptase and prostaglandin. Histamine has a direct effect on nasal blood vessels causing swelling and nasal obstruction. It also has a reflex effect via sensory nerves causing sneezing, itching and further mucus production. This triggers a sequence of events with sneezing followed by watery nasal discharge and finally nasal blockage.
Subsequent nasal symptoms that develop between 3 and 12 hours after the initial allergen exposure are due to the Late Phase Reaction. Further immune mediator production occurs in the already inflamed nasal membranes and blood cells (eosinophils and basophils) infiltrate causing progressive nasal blockage and swelling.
Nasal hypersensitivity occurs when non-allergenic irritants such as dusts, perfume, tobacco smoke, ozone, sulphur dioxide, nitrogen dioxide, cold air and other environmental pollutants result in increased nasal membrane leakiness, increased nerve excitability, white blood cell infiltrates and more mast cells in the superficial nasal membranes. These factors lead to an increased nasal irritability to low doses of allergens. Some older blood pressure medications such as reserpine, methyldopa, ACE inhibitors and alpha blockers as well as hormone replacement therapy (HRT) may in addition cause nasal obstruction. The last trimester of pregnancy is associated with worsening of nasal symptoms due to hormonal factors. While aspirin sensitive individuals will often develop rhinitis, sinusitis and nasal polyps after aspirin re-exposure.
Investigating allergic rhinitis.
We try initially to identify the allergen involved by taking a good allergy history and doing a thorough examination of the nose. We then try to confirm the cause of the allergy by Skin Scratch Testing or with blood tests such as specific IgE or Cap RAST testing.Simple rhinoscopy or nasal examination using a good light-source will demonstrate pale bluish swollen nasal membranes, a moist discharge and occasionally evidence of polyps (grape-like swellings inside the nose).
Skin Scratch Tests for the common inhalant allergens are a very simple and cheap to perform and results are immediately available. Allergen test kits are available from ALK-Abello and Diagenics. These include extracts of House-dust mite, Cat, Dog, Mould spores, Grass and Tree Pollen. Skin tests help to confirm the causative allergen and the "weal and flare" reaction on the skin will demonstrate the inflammatory nature of allergic rhinitis to the patient.
Blood specimens can be drawn and sent to a pathologist for RAST testing. The Phadiatop is an excellent screening test for the common inhalant allergens implicated in allergic rhinitis, if this test is positive, individual UniCAP RAST tests are performed to determine the exact inhalant allergen. If food allergy is strongly suspected in children, the Paediatric Food Mix fx5 food screen (cow’s milk, wheat, egg, peanut, fish, and soya) is recommended. Total IgE may not be elevated in allergic rhinitis, unless there is associated asthma or eczema. Parasite or worm infections and cigarette smoking may also confuse the issue by artificially raising the blood Total IgE.
A useful laboratory test in allergic rhinitis is to take a nasal mucus sample and test for white blood cells called eosinophils using Hansel’s Stain. If plenty of eosinophilic white blood cells are present, this helps to confirm the diagnosis of allergic rhinitis.
Radiology (sinus x-rays and CAT scanning) does not help in the diagnosis of allergic rhinitis, but will identify complications such as chronic sinusitis, infections, nasal polyps and sinus fluid levels.
Nitric oxide (NO) gas levels in air expired from the nasal passages tends to be higher in nasal allergic inflammation. This test is a useful measure of the degree of allergic inflammation, particularly in chronic persistent rhinitis.
Specialist nose surgeons make use of fibre-optic nasal endoscopes to visualise the nasal membranes, septum and osteo-meatal complex of the nasal sinuses. Rhino-manometry which is a measure of nasal air flow, nasal provocation tests with the chemical histamine and microscopy of nasal mucus specimens are of practical use for research purposes.
In a minority of patients with typical symptoms of nasal allergy, all allergy tests prove negative. We refer to these sufferers as having Chronic Non-allergic Rhinitis or Idiopathic Rhinitis. They are treated in a similar fashion to Allergic Rhinitis using the ARIA Guidelines. Some have profuse symptoms with eosinophil cells present in their nasal mucus and this condition is termed Non-allergic Rhinitis with Eosinophilia Syndrome (NARES).
Once the offending allergen is identified, then Allergen Avoidance measures can be instituted. Grass pollens can be avoided, pets removed from the home and mattresses, pillows and carpets treated to eradicate house dust mites. If a particular food is implicated in allergic rhinitis, then that food should be excluded from the diet. Cigarette smoking should be strongly discouraged in all allergic individuals, as it will only exacerbate symptoms. Where allergen avoidance fails or is impractical, read more
