What is the management of Arnold's ear-cough reflex?

Management of Arnold's Ear-Cough Reflex

The management of Arnold's ear-cough reflex primarily involves examination and removal of any foreign material or structure from the ear canal that may be stimulating the auricular branch of the vagus nerve. 1

Understanding Arnold's Ear-Cough Reflex

Arnold's ear-cough reflex occurs in approximately 2.3% to 4.2% of the general population (bilateral in 0.3-2%) and is characterized by cough triggered by stimulation of the external auditory canal. This reflex is mediated by the auricular branch of the vagus nerve (Arnold's nerve) 1.

Key points about prevalence:

• Present in 23-25% of adults with chronic cough 2, 3
• More common in women (29-31%) than men (10-12%) with chronic cough 2
• Usually unilateral (88-90% of cases) 2, 3
• Only present in 2% of healthy adults 2
• Rarely present in children with chronic cough (3%) 2

Diagnostic Approach

1. Ear Examination:

   • Carefully examine the external auditory canal, particularly the posteroinferior and anteroinferior walls 1
   • Look specifically for:
     • Foreign material (including hairs resting on the tympanic membrane) 4
     • Wax impaction 5
     • Cholesteatoma 5

2. Diagnostic Test:

   • The reflex can be elicited by gentle palpation of the posteroinferior wall of the external acoustic meatus or mechanical stimulation with a cotton-tip applicator inserted 3-5 mm for 2-3 seconds 1
   • Cough occurring within 10 seconds of stimulation confirms the reflex 2

Management Algorithm

1. First-line treatment: Remove any stimulating material

   • Carefully remove any foreign material, hair, or wax from the ear canal 1, 4
   • This is often curative when a physical stimulus is present 4

2. For cases with hypersensitivity without obvious physical stimulus:

   • Consider gabapentin therapy for cases where the reflex represents vagal hypersensitivity 5
   • Initial dose: Start with low dose and titrate up as needed
   • Duration: Minimum one month of treatment, as 87.5% of patients with positive Arnold's nerve reflex convert to negative after one month of effective treatment 6

3. Follow-up:

   • Re-evaluate after treatment to confirm resolution of symptoms
   • If symptoms persist, consider alternative or additional diagnoses

Clinical Pearls and Pitfalls

• Important distinction: Arnold's ear-cough reflex may be:

  1. A normal anatomical variant in 2-4% of the population 1
  2. A sign of vagal hypersensitivity in chronic cough patients 5, 6, 2

• Pitfall to avoid: Don't overlook this rare but easily treatable cause of chronic cough, especially in women with unexplained chronic cough 2

• Caution: While examining for thoracic aortic aneurysm in patients with unexplained chronic cough is important, Arnold's nerve reflex should be considered in the differential diagnosis of chronic cough, particularly when other causes have been ruled out 7

• Clinical relevance: The reflex is reversible after effective treatment of the underlying cause of chronic cough, suggesting it may be a marker of general vagal hypersensitivity rather than a specific diagnostic indicator 6