Figure 1. Nasopharyngoscopic evaluation of the velopharyngeal response to the Mueller maneuver during mandibular advancement.

The velopharyngeal response was graded as one of four levels of collapse: (A) slight (< 25% collapse), (B) modest (25% to < 50% collapse), (C) substantial (50% to < 75% collapse), (D) predominant (≥ 75% collapse). The level of collapse was assigned after the operator was satisfied that three consistent observations were obtained.