A 58-year-old male smoker develops a weak, breathy voice over 3 weeks. Indirect laryngoscopy shows an immobile left vocal cord lying in the paramedian position. Chest radiograph reveals a mass at the left hilum. The most likely mechanism of the cord palsy is:

• A Injury to the external branch of the superior laryngeal nerve
• B Invasion of the nucleus ambiguus by metastasis
• C Direct invasion of the left vagus nerve within the jugular foramen
• D Compression of the left recurrent laryngeal nerve in the aortopulmonary window by tumour ✓

Explanation

The left recurrent laryngeal nerve has a longer thoracic course, looping under the aortic arch through the aortopulmonary window before ascending in the tracheo-oesophageal groove. Apical and hilar lung tumours, mediastinal nodes and arch aneurysms can compress it there, making left cord palsy far more common than right. D jugular foramen lesion would affect the vagus high up and usually brings other cranial nerve palsies, not an isolated cord palsy.

Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.