True statement about the paralysis of the recurrent laryngeal nerve is
Paralysis of recurrent laryngeal nerve common on the left side.
The common causes are

Bronchogenic cancer
Accidental trauma
Thyroid surgery
Thyroid disease (benign or malignant)
Cervical lymphadenopathy
Carcinoma cervical oesophagus
Carcinoma thoracic oesophagus
Aortic aneurysm
Mediastinal lymphadenopathy
Common on left side
50% idiopathic
Cord will lie laterally
Speech therapy given