Cough-variant asthma is a type of bronchial asthma in which the main symptom is a dry, non-productive cough.
Children with cough-variant asthma do not have "classic" asthma symptoms, such as heavy breathing, wheezing or shortness of breath. Since the classic symptoms of asthma are absent, cough variant asthma is usually diagnosed very late with the consequence of the child having symptoms. In addition children get unnecessary courses of antibiotics, cough syrups and nebulisations.
What are the signs and symptoms of cough variant asthma in children?
Cough-variant asthma is a common cause of chronic cough in children, which is a cough that lasts longer than 4-6 weeks. Coughs with asthma occur during the day or at night. Cough in children with cough-variant asthma gets more cough after exercise or when exposed to asthma triggers or allergy-causing substances like dust, smoke, deodorants or perfumes, cold air, etc. Night time cough disrupts sleep in children with cough variant asthma.
How is Cough-Variant Asthma diagnosed?
Cough-variant asthma is difficult to diagnose as the only symptom is cough and the other classical symptoms of asthma like wheezing, breathlessness are absent. Other causes of chronic cough like allergic rhinitis, sinusitis, bacterial bronchitis, tuberculosis etc needs to also be considered.
A detailed medical case history is taken and examination including listening to your child’s breath is done. Most kids with a cough variant asthma have normal physical exams. Basic investigations would include a Xray chest and a lung function testing.
Lung function testing includes spirometry and impulse oscillometry. Spirometry also known as the blowing test can be performed in children over 5-6 years of age. This involves breathing and blowing into a device called a spirometer. Spirometry test measures how much air a child can exhale after taking a deep breath in, and how quickly the child can empty the lungs. The test is repeated after giving a bronchodilator medicine to assess the change in values. In children with cough variant asthma the spirometry is showing low values of FEV1 and FEV1/FVC ratio and will show improvement after bronchodilator medicine.
Impulse oscillometry is an advanced lung function modality which involves slow normal breathing into the oscillometry equipment and hence can be done in young children from 3 years onwards. In children with asthma it shows raised values of resistance with improvement after bronchodilator medicine.
In some situations the results of the tests are equivocal. In such situations a trial of asthma medicines is advised. A clear improvement in symptoms clinches the diagnosis of a cough-variant asthma.
How is Cough-Variant Asthma treated?
Cough-variant asthma is usually treated in the same way that typical asthma is treated. The child would require asthma prevention medicine either in the form of montelukast or an inhaler with inhaled steroids (anti-inflammatory agents). Some children in addition would require a bronchodilator for a short duration. Gradual improvement in asthma symptoms is seen over 1-2 weeks.
If your child is having persistent or chronic cough you need to get in touch with a pediatric pulmonologist for proper evaluation, diagnosis and treatment.