How to diagnose and treat upper airway cough syndrome (UACS) with postnasal drip and chronic cough?

Diagnosis of Upper Airway Cough Syndrome (UACS)/Postnasal Drip Syndrome

The diagnosis of Upper Airway Cough Syndrome (UACS) is primarily clinical and confirmed through a therapeutic trial of appropriate medications, as there is no definitive diagnostic test for this condition. 1

Clinical Presentation

UACS is characterized by the following signs and symptoms:

• Sensation of something draining into the throat
• Need to frequently clear the throat
• Tickle in the throat
• Nasal congestion or discharge
• Hoarseness (in some cases)
• Mucoid or mucopurulent secretions visible in the nasopharynx/oropharynx
• History of recent upper respiratory illness
• Wheeze (in some cases) 1, 2

It's important to note that approximately 20% of patients with UACS-induced cough are unaware of either the presence of postnasal drip or its connection to their cough, making this a "silent UACS." 1

Physical Examination Findings

Look specifically for:

• Drainage in posterior pharynx
• Evidence of throat clearing
• Nasal discharge
• Cobblestone appearance of oropharyngeal mucosa
• Visible mucus in oropharynx 1

These findings are relatively sensitive but not specific, as they can be present in patients with cough due to other causes.

Diagnostic Algorithm

1. Clinical Evaluation:

   • Assess for characteristic symptoms and physical findings
   • Consider duration of symptoms (chronic cough is defined as lasting >8 weeks) 3
   • Evaluate for associated conditions (allergic rhinitis, perennial nonallergic rhinitis, postinfectious rhinitis, bacterial sinusitis, etc.) 1

2. Rule Out Red Flags:

   • Hemoptysis
   • Significant weight loss
   • Fever
   • Abnormal chest imaging
   • Smoking history

3. Empiric Treatment Trial:

   • Since there is no definitive test for UACS, an empiric trial of therapy serves as both diagnostic and therapeutic 1
   • First-line treatment: Intranasal corticosteroids (e.g., fluticasone) 2, 4
   • Second-line treatment: First-generation antihistamine/decongestant combination 1, 2
   • Resolution of cough with treatment confirms the diagnosis

4. Consider Alternative or Concurrent Diagnoses:

   • Asthma
   • Gastroesophageal reflux disease (GERD)
   • Eosinophilic bronchitis
   • Chronic bronchitis
   • Bronchiectasis 5

Common Pitfalls in Diagnosis

1. Failing to consider "silent UACS" - Not all patients with UACS will have obvious postnasal drip symptoms 1

2. Overlooking UACS as a cause of chronic cough - UACS, along with asthma and GERD, accounts for up to 90% of chronic cough cases 6

3. Misinterpreting treatment response - Resolution of cough with first-generation antihistamines may be due to their central antitussive effect rather than treating underlying UACS 1

4. Not considering GERD as a mimicker - GERD can present with upper respiratory symptoms similar to UACS 1

5. Inadequate duration of treatment trial - Resolution of cough with treatment typically takes days to weeks 1

Special Considerations

• The term "Upper Airway Cough Syndrome" is now preferred over "Postnasal Drip Syndrome" as it better reflects the pathophysiology, which may involve direct irritation of cough receptors in the upper airway rather than just postnasal drip 1, 7

• Some researchers suggest that UACS may be a clinical phenotype of cough hypersensitivity syndrome, where patients have increased sensitivity of airway cough receptors 7, 8

• Laryngoscopy may be helpful in evaluating patients with persistent symptoms to assess for other causes of throat clearing such as Laryngopharyngeal Reflux (LPR) 2

By following this diagnostic approach, clinicians can effectively identify and manage UACS, leading to improved quality of life for patients suffering from chronic cough.