Unusual asthma syndromes and their management

Abstract

Asthma usually presents with symptoms of wheeze, dyspnoea and cough. However, clinicians should be aware of atypical presentation of this disorder when cough is the main or only symptom in conditions such as cough-variant asthma, nonasthmatic eosinophilic bronchitis and atopic cough. Early diagnosis and treatment of these conditions with inhaled corticosteroids improves symptoms in the majority of patients. Up to 10% of patients with asthma remain poorly controlled in spite of optimal standard therapy. These patients have been encompassed under the term 'treatment-refractory asthma' (TRA), have the greatest morbidity and are responsible for more than 50% of healthcare costs. In this review we discuss investigations, management and pathophysiology of the various phenotypes of atypical presentations of asthma as well as novel biological agents licensed and those that have been reported in clinical trials in terms of their efficacy and safety in TRA.

Cough Variant Asthma as a Phenotype of Classic Asthma

“…The peak expiratory flow (PEF) assessment does not show any variability in CVA patients [2]. The spirometric measurements are normal in patients with CVA [2].…”

“…The results of studies have shown that BAL and sputum in patients with CVA contain an increased percentage of eosinophils [2]. Also, the studies showed that there was no significant difference between CVA and classic asthma in the sputum levels of eosinophilic cationic protein, interleukin 8 (IL-8) and levels of exhaled nitric oxide (FeNO) [2,7,12,17,18]. Studies have suggested that the basic pathophysiological characteristics of CVA are eosinophilic inflammation and AHR [3].…”

“…Corrao and colleagues defined "cough variant asthma" as AHR, chronic cough and absence of wheezing [5]. The peak expiratory flow (PEF) assessment does not show any variability in CVA patients [2]. The spirometric measurements are normal in patients with CVA [2].…”

“…Asthma could be defined more as a syndrome characterized by several different phenotypes [1][2][3]. Therefore, one of the possible definitions describing the characteristics of the disease and unifying more different definitions could define asthma as chronic inflammatory disease characterized by acute variable onset of symptoms (coughing, air deficiency, chest tightening) with bronchoconstriction (clinical definition) reversible and passes spontaneously or under develop classic asthma with wheezing [3].…”

“…A smaller number, about 10% of patients with CVA and with adequate therapy (bronchodilator, ICS or Montelukast) develop classic asthma. A good response of chronic cough to the therapy with ICS cannot be used to distinguish other cough present diseases (atopic cough, non-asthmatic eosinophilic bronchitis) from CVA [2,8].…”