Lee LA, et al. - Authors conducted a pilot study to examine the surgical response to upper airway (UA) surgery directed by drug-induced sleep computed tomography (DI-SCT) for obstructive sleep apnea (OSA). They recruited 29 OSA patients (median age, 41 years; median body mass index, 26.9 kg/m2) who had single-stage DI-SCT-directed UA surgery between October 2012 and September 2014. In nonresponders, despite multilevel OSA surgery, multiple mechanisms are to blame for residual UA obstruction. The reasons for nonresponse may be clarified with DI-SCT. Significant improvements in velopharyngeal, oropharyngeal lateral wall, and tongue collapses were seen in the nonresponders, while significant improvements in velopharyngeal and oropharyngeal lateral wall collapses were seen in the responders.