PHARYNGEAL AIRWAY VOLUME FOLLOWING ...

structures causes the airway muscles to elongate, become
more tense, and have a lesser tendency towards collapse
during sleep. 34
The success rate of MMA surgery has largely been
measured by the Respiratory Distress Index (RDI). Criteria
for success vary between an RDI of less than 10 and an RDI
of less than 20. Utilizing an RDI criteria of less than
10, the success rates of MMA have been reported as 65%, 35
80%, 32 and 97%. 36 Success rates of 83%, 37 90%, 38 97%, 39 and
100% 33 have been documented when an RDI of less than 20 was
the treatment goal.
Cephalometric Studies
Several researchers have quantified the amount of
surgical advancement and measured the structural
anteroposterior (A-P) airway changes following MMA
osteotomy utilizing a lateral cephalogram. The most
frequently measured site is the posterior airway space
(PAS), which is the distance between the base of the tongue
and the posterior pharyngeal wall (PPW). 40 A reference line
from point B through gonion to the PPW is typically used. 41
Other measurements include the upper retropalatal airway
space, narrowest retropalatal space, lowest retropalatal
space, and narrowest retroglossal airway space. The upper
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