Are the obstruction sites visualized on drug-induced sleep endoscopy reliable?

Drug-induced sleep endoscopy (DISE) has been claimed to be a reliable tool, improving surgical results in obstructive sleep apnea syndrome (OSAS). One means of assessing reliability would be to ablate only a part of the sites observed on endoscopy and find only partial success versus ablating all observed sites and finding resolution of apnea.

A retrospective study included 24 OSAS patients, operated on following awake clinical examination. DISE was performed prior to surgery. Overnight sleep study was performed before and after surgery. Two groups of patients were obtained: success (postoperative apnea-hypopnea index (AHI) <10 and >50 % reduction in preoperative AHI) and failure. Obstruction sites found on DISE and those ablated or left after surgery were compared between the two groups.

Mean AHI fell from 30.9 ± 12.4/h to 13.7 ± 14.2/h after surgery. In eight of the 14 patients in the success group, DISE showed an obstruction site not treated by surgery. In six patients out of the ten patients in the failure group, all DISE sites were treated by surgery, which nevertheless was not effective. Four patients had retrovelar concentric obstruction.

DISE could in some cases explain surgical failure. However, it also seems to show additional obstruction sites which do not need to be treated. Proper knowledge of pharyngeal fluid dynamics and mastery of the DISE technique would probably help us understand better some of the DISE findings.