Non-Allergic Rhinitis (Kỳ 2)

Rhinitis MedicamentosaRhinitis medicamentosa (RM) is a condition that caused by overuse of topical nasal steroids. Also known as rebound or chemical rhinitis, the incidence is somewhere between 1-9% of non-allergic rhinitis and it is more common in younger adults and pregnant women.To understand the cause of RM, we must first look at some of the basic science behind the nasal mucosa. The mucosa is innervated by sympathetic fiber that release norepinephrine, which stimulate alpha 1 and alpha 2 receptors. This in turns causes vasoconstriction.The sympathomimetic amines and imidazoline derivatives (phenylephrin and oxymetazoline, respectively) both produce vasoconstriction by endogenous release...
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Non-Allergic Rhinitis (Kỳ 2) Non-Allergic Rhinitis (Kỳ 2) Rhinitis Medicamentosa Rhinitis medicamentosa (RM) is a condition that caused by overuse oftopical nasal steroids. Also known as rebound or chemical rhinitis, the incidenceis somewhere between 1-9% of non-allergic rhinitis and it is more common inyounger adults and pregnant women. To understand the cause of RM, we must first look at some of the basicscience behind the nasal mucosa. The mucosa is innervated by sympathetic fiberthat release norepinephrine, which stimulate alpha 1 and alpha 2 receptors. This inturns causes vasoconstriction. The sympathomimetic amines and imidazoline derivatives (phenylephrinand oxymetazoline, respectively) both produce vasoconstriction by endogenousrelease of norepinephrine. The problem arises with prolonged use. This leads to reduced productionof norepinephrine in the presynapes and decreased sensitivity of the alphareceptors in the postsynapes, which in turn requires higher doses for shorter actingtime. This cycle of excess dose use and decrease symptomatic relief will lead toworsening of the original symptoms. The risk of RM is greatest after 10 days use of medications. Treatmentincludes gradual stopping of decongestant with introduction of topicalcorticosteroid. This will lead to a temporary increase in symptoms and patentsshould be warned beforehand of this and to not restart the original medication.Patients should be off the medication for 3 months before starting any othersurgical or medical treatment for the original nasal disease. NARES NARES (non-allergic rhinitis with eosinophilia syndrome) is another non-allergic entity that is defined as rhinitis without allergic cause but has 20-25%eosiniophils seen on nasal smears. As with the other NAR disease, there is lack ofallergy by skin test or IgE antibodies. Prevalence is 13-33% of NAR. NARES etiology is unknown. However, it is believed to be associated withthe ASA triad as NARES patients tend to develop asthma and nasal polyps later inlife and they tend to have abnormal prostaglandin metabolism. And yet,eosinophilic counts are elevated in 20% of the nasal smears in the generalpopulation and not everyone with eosinophilias have symptom of rhinitis. Recent studies by Powe et al (2001) show that NARES is a local IgEmediated response that does not result in a systemic response. They found that50% of non-allergic rhinitis pt that had a negative skin prick test were found tohave positive result to nasal allergy challenge. Therefore, skin prick tes negativept with eosinophilia may require allergen challenge nasally before diagnosis ofnon-allergic rhinitis. This is important to know, because NARES is a subset ofnon-allergic rhinitis who responds better to nasal corticosteroids than other non-allergic rhinitis groups. Hormonal Rhinitis Hormonal rhinitis (HR) is defined as rhinitis during period so knownhormonal imbalance. Estrogens are known to affect the autonomic nervoussystem by increasing a host of factor including parasympathetics, acetyl cholinetransferase, and acytycholine content, and also increase inhibition of sympatheticsystem. Therefore, the most common causes are pregnancy, menstruation, pubertyand exogenous estrogen. With pregnancy, HR usually manifests in the secondmonth and will continue throughout pregnancy. Hypothyroidism is also known to cause hormonal rhinitis. Inhypothyroidism, increase TSH release causes edema of the turbinates. Nasalcongestion and rhinorrhea are the most common symptoms of RH. Idiopathic rhinitis Next we come to Idiopathic rhinitis (IR). This is also known as vasomotorrhinitis and is characterized by nasal blockage and rhinorrhea, with some sneezingand pruritis. Etiology is unclear, with failed attempts to differentiate byhyperactivity to histamine, methacholine, cold air or capsaicin. IR is solelydiagnosed by patient complaints and therefore a diagnosis of exclusion. The exclusion criteria include: having positive skin test, smoking, nasalpolyps, pregnancy, medications affecting nasal function, and good response tonasal steroids. Pt who have a good response to nasal steroids tend to haveNARES. IR is not believed to be caused by inflammation. IR patients have nosignificant increase in mucosal lymphocytes, antigen presenting cells, eosinophils,macrophages, mast cells or IgE positive cells compared to controls. And studieshave shown a reduction in immunocompetent cells in the mucosa of IR pt aftertreatment with nasal steroids did not reduce nasal complaints. Others Finally we come to the last group of NAR, the other category. There are anumber of conditions that can produ ...