Huge laryngeal saccular cyst causing obstructive sleep apnea

When diagnosing OSA, it is important to identify the cause of upper airway stricture before introducing Nasal continuous positive airway pressure (nCPAP). Obstructive sleep apnea (OSA) caused by laryngeal lesions is very rare [1, 2]. Furthermore, autopsy cases of sudden death due to laryngeal cysts have been reported [3, 4].

A 57-year-old woman was diagnosed with severe OSA and nCPAP was introduced. Her polysomnography (PSG) revealed an apnea index (AI) of 16.1 events/h, a hypopnea index (HI) of 30.8 events/h, and an apnea-hypopnea index (AHI) of 46.9 events/h, with a minimum and mean SpO₂ of 72%, and 93%, respectively, and maximum apnea and hypopnea durations of 110 s and 60 s, respectively. The patient`s measurements were as follows: height, 144 cm; weight, 52 kg; and resting SpO₂, 96%. Two years after the introduction of CPAP, the patient visited our department with hoarseness for 4 months. She had voice change, but no dyspnea. Preoperative snoring did not improve with side-sleeping position. Laryngoscopy revealed a lesion that almost occupied the laryngeal cavity from the left side of the upper glottis, so her vocal cords were difficult to observe (Fig. 1). A contrast-enhanced computed tomography scan showed a 33 × 27 × 24 mm lesion. We decided to perform a transoral cystectomy. On the morning of the surgery, approximately 7 mL of fluid was aspirated, and the patient's vocal cords were made visible, allowing the surgery to be performed under general anesthesia with oral intubation. The cystic lesion occupying the left side of the laryngeal cavity was carefully removed by an oral approach without damaging the capsule. Pathology showed a cystic lesion consisting of squamous epithelial structures and yellow fluid in the lumen, leading to our diagnosis of a laryngeal saccular cyst. OSA disappeared postoperatively and CPAP was no longer necessary. Her mild snoring remained but improved in the side-sleeping position. PSG performed 2 months after surgery showed marked improvement, with an AI of 0.4 events/h, HI of 11.5 events/h, AHI of 11.9 events/h, minimum SpO₂ of 80%, mean SpO2 of 96%, maximum apnea duration of 20 s, and maximum hypopnea duration of 47 s.

Fig. 1.

Endoscopic view of the larynx at the initial consultation

In the present case, we diagnosed a lateral medial type of saccular cyst because it remained in the laryngeal cavity and the aryepiglottic folds were distended from the false vocal cords. Diagnosis is easy with laryngoscopy or contrast-enhanced CT. Thabet reported that Oral resection has a high risk of recurrence in cysts larger than 3 cm [5]. In the present case, the cyst had a diameter of over 3 cm in diameter, and oral intubation was considered difficult according to the laryngoscopy findings at the time of initial examination. Therefore, a portion of the fluid was aspirated from the neck prior to the surgery to allow for safe oral intubation. Complete removal of the cyst dramatically improved postoperative PSG results and allowed the patient to avoid nCPAP. One year after the surgery, the cyst has not recurred. The reason for the delay in detection is deemed to be that the saccular cyst was located above the vocal folds, which are not easily affected by speech or swallowing. It is important to collaborate with an otolaryngologist to rule out the involvement of tumors or cysts that may occur in the upper airway as a causative disease in determining the treatment strategy for OSA.

Author contributions

MH: contributed to the design of the report, collected data, and drafted the manuscript. SF, YI collected data. RK: approved the final version of the manuscript.

Funding

There is no funding.

Declarations

Conflict of interest

All authors have seen and approved this manuscript. The authors report no conflicts of interest.