### Date : 2024-11-04 18:41 ### Topic : Cough-Variant Asthma #pulmonology ---- **Cough-Variant Asthma (CVA)** is a form of asthma where **chronic cough** is the primary or sole symptom, without the classic asthma symptoms of wheezing and shortness of breath. This cough is often **dry, persistent, and worse at night** or after exposure to triggers. CVA can be challenging to diagnose, as the lack of typical asthma symptoms may lead to misdiagnosis as a respiratory infection or postnasal drip. ### Pathophysiology In CVA, the same underlying mechanisms of asthma are present but are manifested primarily through coughing rather than overt wheezing or airway constriction: 1. **Airway Hyperresponsiveness**: - The airways are overly sensitive and react strongly to triggers, such as allergens, cold air, or irritants, causing a cough response. 2. **Inflammation and Bronchoconstriction**: - Inflammatory cells, especially eosinophils, accumulate in the airways, leading to swelling and increased mucus production. - Mild bronchoconstriction may be present but is not severe enough to cause wheezing; instead, it triggers coughing as a protective reflex. ### Causes and Triggers Cough-variant asthma can be triggered by similar factors as classic asthma, including: - **Allergens**: Pollen, dust mites, pet dander, and mold. - **Irritants**: Smoke, strong odors, and pollution. - **Cold Air**: Breathing in cold air can irritate sensitive airways, leading to coughing. - **Exercise**: Physical activity, especially in cold or dry air, can provoke coughing in individuals with CVA. - **Respiratory Infections**: Viral infections may worsen CVA symptoms, leading to prolonged coughing after the infection has resolved. ### Symptoms The primary and often only symptom of cough-variant asthma is a **chronic, dry cough** that lasts for at least **6–8 weeks** and is typically: - Worse at night or early in the morning - Triggered by exercise, cold air, allergens, or irritants - Persistent and unresponsive to typical cough treatments, such as antitussives or antibiotics ### Diagnosis Diagnosing CVA can be challenging due to the lack of wheezing or obvious respiratory distress. Diagnosis often requires a combination of history, physical examination, and specific tests: 1. **History and Symptom Analysis**: - Chronic cough lasting several weeks or more, often without other respiratory symptoms. - History of symptoms worsening at night, with exercise, or after exposure to known asthma triggers. 2. **Pulmonary Function Tests (PFTs)**: - **Spirometry**: May show normal results if no overt bronchoconstriction is present. - **Methacholine Challenge Test**: This test is often used when spirometry is normal. Methacholine is a bronchoconstrictor, and in patients with CVA, it can provoke coughing or show airway hyperresponsiveness, supporting the diagnosis of asthma. 3. **Exhaled Nitric Oxide (FeNO) Test**: - Measures the level of nitric oxide in exhaled breath, which is often elevated in asthma due to airway inflammation. 4. **Trial of Asthma Medications**: - In some cases, a **trial of asthma therapy** (e.g., inhaled corticosteroids and bronchodilators) is used to confirm diagnosis. Improvement in cough symptoms with these medications suggests CVA. ### Treatment Treatment for cough-variant asthma is similar to that for classic asthma and focuses on controlling inflammation and preventing symptoms: 1. **Inhaled Corticosteroids (ICS)**: - The mainstay of treatment, ICS reduce airway inflammation and help control symptoms over the long term. - Examples include **fluticasone** and **budesonide**. 2. **Short-Acting Beta-Agonists (SABA)**: - **Albuterol** or other SABA inhalers are used as needed for quick relief, especially if cough worsens with exercise or exposure to triggers. 3. **Leukotriene Receptor Antagonists**: - Medications like **montelukast** can help control cough and inflammation, especially if allergens are a significant trigger. 4. **Long-Acting Beta-Agonists (LABA)**: - For persistent or severe symptoms, a LABA may be added to ICS therapy for better control. 5. **Avoidance of Triggers**: - Identifying and avoiding known triggers (e.g., allergens, smoke, cold air) can help prevent cough episodes. 6. **Managing Comorbidities**: - Conditions like gastroesophageal reflux disease (GERD), postnasal drip, or sinusitis can exacerbate CVA, so managing these can also help reduce coughing. ### Prognosis With appropriate treatment, most patients with CVA experience significant improvement in cough symptoms, and some may even achieve complete remission. However, untreated CVA can progress to classic asthma with symptoms of wheezing and shortness of breath, so early diagnosis and treatment are essential. ### Summary - **Cough-Variant Asthma** is a form of asthma where chronic cough is the main symptom, without the classic signs of wheezing. - **Diagnosis** involves a combination of patient history, pulmonary function testing, and response to asthma therapy. - **Treatment** includes inhaled corticosteroids, short-acting beta-agonists, and lifestyle modifications to avoid triggers. - **Prognosis** is generally good with proper management, but untreated CVA can progress to classic asthma. Recognizing cough-variant asthma early and initiating treatment can help prevent symptom progression and improve quality of life for patients experiencing chronic cough. ### Reference: - ### Connected Documents: -