A Thyroglossal Duct Cyst Causing Obstructive Sleep Apnea in Adult
A 51-year-old man visited the Sleep Center with a 2-year history of snoring and voice change. He had complaints about loud snoring and had been witnessed to have obstructive sleep apnea with excessive daytime somnolence. His Epworth sleepiness scale (ESS) score was 13. He denied any history of dyspnea. His medical history included mild hypertension and diabetes. His height was 160 cm, his weight was 62 kg and his body mass index was 24.2 kg/m2.\nOn physical examination, his Friedman tongue position [] was grade III (only the soft palate is visible) and the tonsils were hidden in the tonsillar fossa. On flexible laryngoscopy, about a 20×20 mm sized round cystic mass at the base of tongue was identified. The cyst bended the epiglottis posteriorly, which made the airway narrow. The vocal cords could not be observed because of the lesion ().\nHe underwent a full-night laboratory nocturnal polysomnography (PSG). PSG revealed that the respiratory disturbance index (RDI) was 32.2 events per hour of sleep with the supine RDI of 105.8 events/h. The longest apnea duration was 39.7 seconds. The lowest SaO2 was 89%, and the average SaO2 saturation was 97.2%.\nThe computed tomograms showed a 33×31×27 mm sized well-defined cystic lesion located at the midline of the tongue base, compressing the oropharyngeal airway (). The epiglottis was displaced posteriorly by the cystic lesion.\nTo evaluate the upper airway obstruction and to find any other obstructive lesion, sleep videofluoroscopy (SVF) was performed with administration of 0.05 mg/kg of midazolam as described previously []. SVF showed that the pharyngeal airway was completely obstructed during both inspiratory and expiratory phase when the mass pulled the epiglottis down and backward. The tip of epiglottis was in contact with the posterior pharyngeal wall irrespective of respiratory cycle ().\nSistrunk operation was performed via external approach instead of oral approach, because the mass was somewhat large. Round cystic mass was removed uneventfully. Soon after the operation, the signs and symptoms of OSA such as snoring and daytime sleepiness ceased and his voice was normalized. His ESS score reached 4.\nPostoperative flexible laryngoscopy showed that the mass was disappeared completely (). Postoperative PSG (3 months after operation) showed that all the parameters were nearly normalized or improved. The RDI decreased to 4.0 events per hour and the supine RDI decreased to 13.4 events per hour. The longest apnea duration was 26.5 sec. The lowest SaO2 was 92%, and the average SaO2 saturation was 97.8%.\nPostoperative SVF showed that the displaced epiglottis returned to normal position and the pharyngeal airway was not collapsed, however, during inspiration the hypopharyngeal airway was partially obstructed at the level of the epiglottis, which could explain the remnant RDI of 4.0 ().\nThe histopathology showed that the cyst was lined by stratified squamous epithelium, and that the deeper tissue showed fibrosis, skeletal muscle fragments and laryngeal gland cysts, which was consistent with a TGDC (). There has been no evidence of recurrence for 1 year.