We describe a case of hoarseness that did not appear immediately after surgery but did appear 3 months later and a severe complication of a large laryngopharyngeal cyst that resulted in airway obstruction after laryngoscopy.

Laryngeal damage is a common complication of tracheal intubation, but among such injuries, vocal cord cysts are rare [2]. The occurrence of laryngeal injury is associated with a variety of factors, including the intubation conditions [4], thickness [5,6,7] and material of the tracheal tube [8], duration of indwelling of the tracheal tube [9, 10], sex [10], and history of gastroesophageal reflux disease [11]. The dual-lumen tracheal tube is specialized for performing one-lung ventilation during perioperative thoracic surgeries, and its distinct structure (thicker outer diameter, long and curved) and high degree of technical difficulty in completing DLTs lead to a higher incidence of pharyngeal ventilation than that with single-lumen tracheal tubes [10, 12, 13]. This patient is female and represents a high-risk population [10]. A DLTs with a thick outer diameter was inserted [5,6,7]. The indwelling endotracheal tube time was 172 min, and a time of more than 120 min further increased the incidence of glottic cyst [2].

Studies have found that heating the DLTs can also reduce the throat pain caused by the DLTs and even improve the throat complications of endotracheal intubation in patients with a high risk of smoking and COVID-19 [14,15,16].

Sequelae of laryngeal injury caused by tracheal intubation, such as sore throat and hoarseness, have the highest incidence on the first postoperative day [17], and therefore, most current scholars have studied the outcome of postoperative hoarseness within 1 week. According to the English literature retrieved thus far, Friedrich and other scholars have studied voice changes over a relatively long postoperative follow-up period of 4–9 days [18]. Yamanaka et al. reported longer follow-up periods, with the greatest duration being 21 days [17]. However, both studies included patients who developed hoarseness on the first postoperative day and continued to be followed. The reported duration of follow-up for pharyngeal complications after DLTs is relatively short (approximately 1–3 days) [14,15,16]; in contrast, the hoarseness that appeared in our case at approximately 3 months after the operation was not a case in which the hoarseness appeared on the first day of the postoperative period and persisted, and no similar reports or studies have been published.

Vocal cysts are secondary pharyngeal injuries caused by tracheal intubation [2], and such damage usually resolves within 1 week postoperatively [3] and, in some cases, up to 2–3 months later [19]. In new postoperative cases that do not improve by 48 h after surgery, Martin B and other scholars recommend laryngoscopy, which allows early treatment to avoid serious complications [2], and head and neck surgery experience in the United States similarly suggests that new voice changes occurring between 2 weeks and 2 months after surgery should be examined via laryngoscopy as soon as possible, regardless of the duration of the surgery [20]. In the case reported in this article, the patient did not complain of significant sore throat or hoarseness within 24 h after surgery but developed hoarseness approximately 3 months after surgery, which exceeded the time of occurrence in the American Head and Neck Surgery expert consensus.

In this case, the patient had dyspnea with upper airway obstruction due to obstruction of the vocal ostium by a large vocal cord cyst, resulting in airflow obstruction and presenting as dyspnea on inspiration. Particularly in the left lateral position, the cyst sagged to the right under gravity, which aggravated the vocal fold obstruction and led to worsened dyspnea. In right lateral recumbency, the cyst prolapsed under gravity toward the left side, reducing the vocal fold obstruction and dyspnea. Therefore, the patient’s dyspnea was more pronounced in the left lateral position and was relieved when the patient turned to the right lateral position. Such a large vocal cyst can cause dyspnea in the obstructive inspiratory phase of a patient, which may endanger the patient’s life at any time and is a delayed but serious complication.