What is the best approach to manage intermittent cough in an elderly patient with Parkinson's disease (PD) and potential comorbid conditions such as Chronic Obstructive Pulmonary Disease (COPD) and Gastroesophageal Reflux Disease (GERD)?

Management of Intermittent Cough in Parkinson's Disease

In Parkinson's disease patients with intermittent cough, systematically evaluate and treat the three most common causes—upper airway cough syndrome (UACS), asthma/eosinophilic bronchitis, and GERD—while recognizing that PD itself causes both motor and sensory cough dysfunction that worsens with disease progression and increases aspiration pneumonia risk.

Understanding Cough Dysfunction in Parkinson's Disease

Parkinson's disease causes specific impairments in cough function that are distinct from other causes of chronic cough:

• Motor dysfunction occurs early in PD, with significantly reduced cough peak flow rates (230 L/min in early PD vs 316 L/min in controls) even at Hoehn and Yahr stages II-III 1
• Sensory dysfunction develops in advanced disease, with impaired cough reflex sensitivity and reduced substance P concentrations in sputum 1
• Sequential cough is particularly impaired in PD patients with dysphagia, affecting the ability to clear aspirate material from airways 2
• Cough dysfunction correlates with aspiration risk, with reflex cough testing showing 77.8% sensitivity and 90.9% specificity for identifying PD patients with dysphagia 3

Initial Evaluation Algorithm

Step 1: Obtain chest X-ray and assess for red flags

• Chest X-ray is mandatory to exclude malignancy, tuberculosis, interstitial lung disease, and heart failure 4
• Immediate investigation required for hemoptysis, weight loss, fever, or night sweats 4
• If chest X-ray is abnormal, pursue diagnosis-specific investigations rather than using the chronic cough algorithm 4

Step 2: Review medications and smoking status

• Stop ACE inhibitors immediately if the patient is taking them, as cough resolves in a median of 26 days but may take up to 4 weeks 4
• Counsel smoking cessation as first-line treatment if applicable, with most patients achieving cough resolution within 4 weeks 4
• Consider that beta-blockers may exacerbate cough by triggering bronchoconstriction 5

Step 3: Perform spirometry

• Spirometry is required in all chronic cough patients to identify airflow obstruction and assess bronchodilator response 4
• Normal spirometry does NOT exclude asthma as a cause of cough 4
• If COPD is present, determine whether cough represents an exacerbation requiring antibiotics or corticosteroids versus stable disease 5

Sequential Treatment Approach for Common Causes

First-Line: Upper Airway Cough Syndrome (Most Common - 44% prevalence)

• Start with first-generation antihistamine-decongestant combination (e.g., chlorpheniramine + pseudoephedrine) for 1-2 weeks 4
• Expect some improvement within days to 1-2 weeks; complete resolution may take several weeks to months 4
• UACS is the most common cause and response guides further management 4

Second-Line: Asthma/Eosinophilic Bronchitis

• Trial oral prednisolone 30-40mg daily for 2 weeks, as no test reliably excludes steroid-responsive cough 4
• Lack of response rules out eosinophilic airway inflammation 4
• If bronchial provocation testing is available and spirometry is normal, perform methacholine challenge 4

Third-Line: Gastroesophageal Reflux Disease

• Start intensive acid suppression with PPI (omeprazole 40mg or pantoprazole 40mg twice daily) plus lifestyle modifications for a minimum of 3 months 4
• Up to 75% of GERD-related cough patients have NO heartburn or regurgitation 4
• Do not give up on GERD treatment too early, as it requires minimum 3 months of intensive therapy 4

Critical Considerations Specific to Parkinson's Disease

Multiple causes are common

• Cough is often multifactorial in PD patients, requiring treatment of all contributing conditions simultaneously 5
• GERD may be particularly prevalent due to PD-related gastrointestinal dysmotility 5
• Maintain all partially effective treatments while addressing additional causes 5

Aspiration risk assessment

• Consider swallowing evaluation if cough is associated with eating or drinking, given the high prevalence of dysphagia in PD 3, 2
• Reflex cough testing with capsaicin or aerosolized water may help identify patients needing formal swallowing assessment 3
• Sequential voluntary cough dysfunction indicates higher aspiration risk 2

Management of Refractory Cough in PD

If cough persists after treating common causes:

• Cough rehabilitation with biofeedback can improve cough effectiveness, as PD patients can volitionally upregulate both reflex and voluntary cough motor output with verbal instruction and visual biofeedback 6
• Gabapentin therapy following dosing protocols for unexplained chronic cough to address cough hypersensitivity syndrome 7
• Multimodality speech pathology therapy including cough suppression techniques and breathing exercises 7
• Low-dose controlled-release morphine as second-line therapy for refractory cough 7

Common Pitfalls to Avoid

• Do not rely on cough characteristics (timing, quality, productive vs dry) for diagnosis, as they lack diagnostic sensitivity and specificity 4
• Do not assume normal spirometry excludes asthma as a cause of cough in PD patients 4
• Do not attribute cough solely to PD without systematically evaluating and treating alternative causes first 7
• Do not use systemic corticosteroids for cough management in PD unless treating concurrent asthma/eosinophilic bronchitis or COPD exacerbation 5, 7
• Avoid acetylcysteine without adequate cough clearance, as increased liquified secretions may accumulate if cough is inadequate, requiring mechanical suction 8