Bilateral recurrent laryngeal nerve palsy is seen in -
Causes of bilateral recurrent laryngeal nerve palsy are: 

Idiopathic
Post thyroid surgery
Thyroid malignancy
Carcinoma of cervical part of esophagus
Cervical Lymphadenopathy.

NOTE:
Peripheral neuritis causes high vagal palsy which leads to both superior as well as recurrent laryngeal nerve palsy i.e. bilateral complete palsy.
Thyroidectomy
Carcinoma thyroid
Cancer cervical oesophagus
All of the above