Can recurrent laryngeal nerve injury cause dysphagia?

Recurrent Laryngeal Nerve Injury and Dysphagia

Yes, recurrent laryngeal nerve (RLN) injury can cause dysphagia, as it impairs the patient's ability to protect the airway during swallowing, which can lead to aspiration and significant morbidity and mortality. 1

Mechanism of Dysphagia in RLN Injury

• RLN injury impairs vocal cord function, compromising airway protection during swallowing, which can lead to aspiration of food and liquids into the trachea 1
• The RLN innervates all intrinsic laryngeal muscles except the cricothyroid, controlling vocal fold movement crucial for both phonation and swallowing 1
• Following RLN injury, patients experience impaired ability to cough effectively in the early post-injury period, further compromising airway protection 1
• Dysphagia occurs not only from vocal fold paralysis but also from disrupted sensorimotor integration affecting multiple muscles involved in swallowing 2

Clinical Presentation

• Symptoms range from mild dysphagia to severe aspiration depending on whether the injury is unilateral or bilateral 3
• Unilateral RLN injury can cause symptomatic aspiration in approximately 28% of patients (5 of 18 patients in a prospective study) 4
• Silent aspiration (aspiration without triggering protective reflexes) can also occur, making clinical detection challenging 4
• Patients may present with concurrent dysphonia or hoarseness along with swallowing difficulties 3

Pathophysiology of Swallowing Dysfunction

• RLN injury affects more than just vocal fold movement - it disrupts the timing, duration, and amplitude of multiple muscles involved in swallowing 2
• The coordination between respiration and swallowing is altered following RLN injury, increasing aspiration risk 5
• Changes occur in muscles that are not directly innervated by the RLN, suggesting complex brainstem sensorimotor integration issues 2
• Both the preparatory (oral) and pharyngeal phases of swallowing can be affected 2

Evaluation of Dysphagia in RLN Injury

• Flexible fiberoptic videolaryngoscopy is recommended to evaluate swallowing function and detect aspiration 4
• Assessment should include evaluation of:
  • Vocal fold position, tone, and tension
  • Glottic axis and arytenoid position/mobility
  • Laryngeal sensibility
  • Status of the pyriform sinus and salivary stasis 4
• Testing with different consistencies (dry swallow, thick liquids, thin liquids) helps determine the severity and nature of dysphagia 4

Management Considerations

• In cases of significant aspiration risk, a tracheostomy may be considered to protect the airway and improve pulmonary toilet 1
• Diet modification (normal, mixed, or blended) based on the severity of dysphagia 4
• Most unilateral RLN injuries show compensation from the opposite vocal cord over time 1
• For persistent dysphagia, interventions such as thyroplasty or vocal cord injections may be considered, though these are rarely required 1
• Electrical stimulation of the recurrent laryngeal nerve via an implanted electrode is a promising but experimental approach for severe dysphagia 1

Special Considerations

• Risk of RLN injury is higher during certain procedures, particularly thyroidectomy, with injury rates of 0.3-3% for permanent and 6-8% for transient damage 1
• The left RLN is particularly vulnerable during mediastinal lymphadenectomy due to its longer course around the aortic arch 1
• Re-operative procedures carry a significantly higher risk of RLN injury (up to 30%) 1
• Bilateral RLN injury presents a medical emergency due to potential complete airway obstruction 1

Understanding the relationship between RLN injury and dysphagia is crucial for proper management and prevention of aspiration-related morbidity and mortality in affected patients.