Unilateral vocal cord paralysis appears to be a frequently encountered condition by otorhinolaryngologists, that often manifests as hoarseness or dysphagia. We encountered some cases that had recovered from unilateral vocal cord paralysis.

We studied the clinical features of patients who had recovered from unilateral vocal cord paralysis, by retrospectively analyzing the data of 135 patients who had been diagnosed as having unilateral vocal cord paralysis at our hospital between December 2010 and October 2015.

In the 135 patients enrolled in the study, the causes of the unilateral vocal cord paralysis were distributed as follows: idiopathic, 38 cases; postoperative, 42 cases; endotracheal intubation, 11 cases; tumor, 30 cases; others, 14 cases. A total of 41 of the 135 cases showed recovery from the paralysis, including 13 of the 38 cases with idiopathic paralysis (34.2%), 17 of the 42 with postoperative paralysis (40.5%), 10 of the 11 in whom the paralysis developed following endotracheal intubation (90.9%), and one of the 30 in which the paralysis was caused by a tumor (3.3%); none of the 14 cases with vocal cord paralysis of other causes showed recovery from the paralysis.

In the cases with idiopathic unilateral vocal cord paralysis, almost complete recovery was noted within 9 months of the appearance of the first symptoms and within 6 months of the diagnosis. In cases with the vocal cord paralysis developing after surgery or endotracheal intubation, near-complete recovery was observed within 4 months of the diagnosis. In patients with postoperative unilateral vocal cord paralysis after thyroid surgery, the intraoperative hemorrhage tended to be less and the operative duration was shorter in the patients who recovered than in those who had permanent paralysis.

Our findings revealed that unilateral vocal cord paralysis developing as a result of endotracheal intubation has a good prognosis, whereas that caused by tumors has a poor prognosis. Surgical procedure for paralysis should be considered on the merits of each case, such as in cases with idiopathic paralysis not improving within 9 months of the appearance of the first symptoms and cases with postoperative paralysis not resolving within 4 months. In cases of paralysis developing after thyroid surgery, the volume of hemorrhage, operative duration and type of operative procedure were found to exert an influence on the likelihood of recovery from the postoperative vocal cord paralysis.