This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Larynx, Subject name: ENT
Following total thyroidectomy the patient develops respiratory stridor. The cause is: 
Select and explain. 
A. B/L recurrent laryngeal nerve paralysis, B. B/L complete paralysis, C. U/L recurrent laryngeal nerve paralysis, D. U/L complete paralysis
A: B/L recurrent laryngeal nerve paralysis
Answer: A: B/L recurrent laryngeal nerve paralysis 
Explanation: (a) B/L recurrent laryngeal nerve paralysis(Ref. Current Diagnosis & Treatment Otolaryngology, Lalwani, 3rd ed., 478)In B/L recurrent laryngeal nerve paralysis the vocal cords will be in median position, leading to stridor.Note: This is the only vocal cord palsy with stridor, breathing is normal in the remaining palsies.