What are the symptoms of vagus nerve irritation?

Symptoms of Vagus Nerve Irritation

The vagus nerve (CN X) is the longest cranial nerve in the body, and its irritation produces a constellation of symptoms primarily involving the pharynx, larynx, cardiovascular system, and respiratory tract, with vocal cord paralysis being one of the most troubling manifestations. 1

Primary Symptoms by Anatomical Distribution

Laryngeal and Pharyngeal Symptoms

• Hoarseness is the most common symptom of vagal dysfunction, resulting from vocal cord paralysis or paresis 2, 3
• Throat pain and dysphagia occur due to impaired pharyngeal muscle function 2, 3
• Palatal weakness manifests when lesions are proximal to the pharyngeal branches, causing the uvula to deviate away from the affected side 1, 4
• Dysphonia develops from recurrent laryngeal nerve involvement affecting all laryngeal muscles except the cricothyroid 1

Respiratory Symptoms

• Chronic cough represents a cardinal manifestation of vagal irritation, occurring through activation of vagal afferent C-fibers and mechanoreceptors in the airways 1
• Shortness of breath results from vocal cord dysfunction or impaired respiratory coordination 2, 5
• Coughing episodes can be triggered by mechanical stimulation of vagal sensory branches, including Arnold's nerve (auricular branch), which causes chronic irritating cough in approximately 2.3% of individuals 6

Cardiovascular Symptoms

• Bradycardia occurs due to excessive parasympathetic tone from vagal stimulation 5
• Pseudoanginal chest pain can manifest as crushing substernal chest pain radiating to the left arm, mimicking cardiac ischemia but without actual cardiac dysfunction 5
• Asystole rarely occurs with severe vagal stimulation 5

Auricular and Referred Symptoms

• Ear pain or irritation develops from stimulation of Arnold's nerve, which supplies sensory innervation to parts of the external ear 6
• Touch-induced cough represents a neurogenic phenomenon where mechanical stimulation of vagally-innervated areas triggers coughing 6

Gastrointestinal Manifestations

• Impaired gastric motility results from disruption of parasympathetic supply to the thorax and abdomen 1
• Reflux-associated cough occurs through vagal-mediated reflexes between the esophagus and airways, even without aspiration 1

Pathophysiologic Mechanisms

Neurogenic Cough Pathway

The vagus nerve mediates cough through two primary sensory pathways 1:

• C-fiber nociceptors in the airway mucosa respond to chemical mediators and inflammatory stimuli
• Mechanically sensitive "cough receptors" positioned beneath the epithelium respond to punctate mechanical stimuli

Sites of Vulnerability

The vagus nerve is susceptible to pathology throughout its extensive course 1:

• Brainstem lesions (demyelination, infarction, neoplasms, syringobulbia) affect the vagal nucleus
• Skull base pathology (meningiomas, schwannomas, paragangliomas, metastases) compress the nerve at the jugular foramen
• Neck lesions (trauma, surgery, tumors, inflammatory disease) damage the cervical vagus
• Thoracic pathology (lung cancer, tuberculosis, aortic aneurysm) affects the recurrent laryngeal nerve in the aortopulmonary window 1

Critical Clinical Pitfalls

Do not dismiss touch-induced cough as psychogenic without proper evaluation, as this represents a recognized neurologic phenomenon involving vagal nerve hypersensitivity, particularly through Arnold's nerve 6

Always image the entire course of the vagus nerve from skull base to mid-chest when evaluating vocal cord paralysis, as lesions anywhere along this extensive pathway can cause symptoms 1

Consider vascular compression of the vagus nerve root (VANCOUVER syndrome) in patients with refractory neurogenic cough, as microvascular decompression can provide complete resolution 7

Evaluate for ACE inhibitor use, as these medications are a well-established cause of vagal-mediated chronic cough and should be discontinued as a therapeutic trial 6