Unilateral recurrent laryngeal nerve palsy post-thyroidectomy: Looking for hyperventilation syndrome

Unilateral Recurrent Laryngeal Nerve (RLN) palsy is responsible for dysphonia and difficulties in swallowing. The role of unilateral RLN palsy on dyspnea is not fully elucidated. Our hypothesis is that air leak could be responsible for development of hyperventilation syndrome (HVS).

The objective of this study was to determine in patients with unilateral RLN palsy if dyspnea could be associated with HVS.

Over a 12-month period, all patients with permanent unilateral RLN palsy after thyroidectomy complaining from the onset of unexplained dyspnea were tested. Measurement of Nijmegen score, an hyperventilation test, an arterial blood gas, lung function and cardiac tests were performed. The diagnosis of HVS was defined if at least two criteria were present among: Nijmegen score>23; reproduction of at least 2 usual symptoms during hyperventilation test; an expirated pressure of CO2 (EpCO2)<30mmHg or<90% of the initial EpCO2 after a 5minutes recovery period following a 3minutes voluntary hyperventilation.

Ten out of 366 patients with thyroidectomy for benign disease had permanent unilateral RLN palsy and dyspnea. Among 10 patients included, 8 were diagnosed having HVS on the hyperventilation test without cardiac/lung dysfunction.

In summary, this study is a proof of concept that HVS might be involved in dyspnea associated with unilateral RLN palsy.