Most common cause of recurrent laryngeal nerve palsy is:
Bronchogenic carcinoma
Thyroid surgery
Mediastinal tumors
Pancoast tumor
"Previous surgery, mostly thyroid surgery, is the most common cause of laryngeal nerve paralysis. Revision thyroidectomy bears a paicularly high risk for inferior and superior laryngeal nerve trauma." - Surgery of Larynx and Trachea by Marc Remacle (2015)/ p271