What is the most likely diagnosis for an adult patient who feels giddy or light‑headed when coughing or sneezing?

Cough Syncope (Tussive Syncope)

The most likely diagnosis is cough syncope (also called tussive syncope), a situational syncope where loss of consciousness occurs as a direct result of coughing or sneezing due to markedly elevated intrathoracic pressures causing cerebral hypoperfusion. 1

Pathophysiology

The mechanism involves multiple hemodynamic consequences of extreme intrathoracic pressure elevation during forceful coughing or sneezing 1, 2:

• Decreased cardiac output from impaired venous return (Valsalva-like mechanism), leading to systemic hypotension and cerebral hypoperfusion 1, 3
• Equalization of arterial and central venous pressures during the cough paroxysm, with concomitant rapid decrease in cerebral blood flow 2
• Increased cerebrospinal fluid pressure causing elevated extravascular pressure around cranial vessels, further diminishing brain perfusion 1
• Neurally mediated reflex vasodepressor-bradycardia response to cough in some patients 1

The typical lack of prodromal symptoms (no warning before fainting) is explained by the rapidly developing cerebral hypoperfusion that occurs within seconds 2.

Typical Patient Profile

The classic presentation includes 1:

• Middle-aged, large-framed or overweight male (most common demographic)
• Underlying obstructive airways disease (COPD, asthma, chronic bronchitis)
• Paroxysmal, forceful coughing episodes preceding syncope
• Immediate loss of consciousness following cough, without prodromal symptoms 2

Critical Cardiac Considerations

While most cases result from hemodynamic mechanisms, rare cardiac causes must be excluded 4, 3:

• Cough-induced complete atrioventricular block with ventricular asystole has been documented 4
• Constrictive pericarditis can precipitate cough syncope by further restricting cardiac filling during elevated intrathoracic pressure 3
• Stenotic arterial lesions in cerebral or coronary circulation are present in approximately 70% of patients demonstrating normal blood pressure overshoot during Valsalva maneuver 5

Diagnostic Approach

Perform Valsalva maneuver testing under continuous cerebral blood flow velocity and blood pressure monitoring to discriminate pathogenic mechanisms 5:

• Absent blood pressure overshoot following relief of straining indicates prolonged hypotension after cough (median 16.4 seconds vs. 2.6 seconds in normal responders) 5
• Normal blood pressure overshoot is associated with higher prevalence of stenotic arterial lesions (70% vs. 12.5%) requiring vascular investigation 5

Obtain ECG monitoring during induced cough to exclude cough-induced arrhythmias, particularly atrioventricular block 4.

Evaluate for underlying cardiac conditions including constrictive pericarditis, especially if other cardiac symptoms are present 3.

Management Strategy

The fundamental treatment principle is elimination of cough, which will eliminate the syncopal episodes 1:

Systematic Cough Evaluation

Conduct thorough evaluation for underlying causes of cough following evidence-based cough management guidelines 1:

• Chest radiograph mandatory in all patients with chronic cough 6
• Spirometry mandatory to assess for obstructive airways disease 6
• Evaluate for the most common causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD), which account for >90% of chronic cough cases 7

Specific Cough Treatment

Treat identified underlying causes aggressively 7:

• For UACS: First-generation antihistamine-decongestant combination plus intranasal corticosteroid spray, with response expected within days to 1-2 weeks 7
• For asthma/cough-variant asthma: Inhaled corticosteroids and long-acting bronchodilators, with complete resolution potentially requiring up to 8 weeks 7
• For GERD: High-dose PPI therapy (omeprazole 40 mg twice daily) with dietary modifications, with response requiring 2 weeks to several months 7

Obstructive Lung Disease Management

For patients with COPD or chronic bronchitis (the typical cough syncope patient) 1:

• Optimize bronchodilator therapy with long-acting beta-agonists and anticholinergics
• Ensure appropriate inhaled corticosteroid use if indicated
• Smoking cessation if applicable, as smoking-related chronic bronchitis can resolve within 4 weeks 7

Common Pitfalls to Avoid

• Failing to recognize cardiac causes: Always exclude cough-induced arrhythmias and structural cardiac disease before attributing syncope solely to hemodynamic mechanisms 4, 3
• Assuming single etiology: Up to 40% of chronic cough patients have multiple simultaneous causes requiring combination therapy 7
• Inadequate treatment duration: Many cough treatments require weeks to months for full response; premature discontinuation leads to treatment failure 7
• Ignoring medication review: ACE inhibitors must be discontinued before pursuing extensive workup, as they are a common iatrogenic cause of chronic cough 7