From the Guidelines
The recurrent laryngeal nerve, particularly the left recurrent laryngeal nerve, is the nerve that lung tumors commonly compress causing vocal cord palsy. This nerve branches from the vagus nerve and has a unique anatomical course, especially on the left side where it loops around the aortic arch before ascending in the tracheoesophageal groove to innervate the intrinsic muscles of the larynx. Due to this long anatomical path, the left recurrent laryngeal nerve is especially vulnerable to compression by tumors in the left lung apex (Pancoast tumors), left hilar masses, or mediastinal lymphadenopathy associated with lung cancer, as noted in the American College of Chest Physicians evidence-based clinical practice guidelines 1. Compression of this nerve leads to paralysis of the ipsilateral vocal cord, resulting in hoarseness, voice changes, and potentially aspiration due to incomplete glottic closure during swallowing.
The diagnosis of vocal cord palsy due to lung tumor compression can be evaluated with contrast-enhanced neck CT extended through the aortopulmonary window, which allows imaging of the jugular foramen, the full extracranial course of the vagus nerve, direct imaging of the larynx, and assessment of the full extent of the recurrent laryngeal nerve 1. Additionally, CT chest can be used to evaluate the intrathoracic course of the vagus nerve and is more sensitive than chest radiographs in detecting thoracic causes of vocal cord paralysis, particularly for detecting aortopulmonary window and paratracheal lesions 1.
This symptom can be an important early indicator of lung malignancy, particularly when hoarseness occurs without obvious explanation in patients with risk factors for lung cancer such as smoking history. Therefore, it is crucial to consider lung cancer as a potential cause of vocal cord palsy, especially in patients with a history of smoking or other risk factors, and to evaluate these patients promptly with appropriate imaging studies.
From the Research
Nerve Compression Causing Vocal Cord Palsy
- The nerve that is compressed by a lung tumor, causing vocal cord palsy, is the recurrent laryngeal nerve 2, 3, 4, 5.
- The recurrent laryngeal nerve can be damaged by direct invasion of lung cancer, particularly those located in the left mediastinum or lung apices 4.
- Compression of the left recurrent laryngeal nerve by a lung tumor can cause unilateral vocal fold paralysis, leading to complete aphonia 3.
- The possibility of recurrent laryngeal nerve palsy should be considered in patients with previous apical lung cancer and/or radiotherapy 2.
- Radiation therapy can also cause recurrent laryngeal nerve paralysis, leading to bilateral vocal cord paralysis 6.
Clinical Implications
- Patients with lung cancer should be monitored for signs of vocal cord palsy, such as hoarseness or breathiness 3.
- Comprehensive rehabilitation therapies, including interferential current therapy, vocal training, and kinesiology taping, may be effective in improving voice recovery in patients with vocal fold paralysis caused by lung cancer 3.
- Gene therapy may be a potential adjunct to enhance nerve regeneration in patients with recurrent laryngeal nerve palsy 5.