As the PNS C-T scans are widely employed, the evaluation of maxillary sinus hypoplasia(MSH) becomes more accurate than using the conventional plain X-rays. Recently, the clinical significance of associated abnormalities in MSH has been suggested.
The
purpose of this study is to investigate the incidence of MSH and their associated abnormalities. We have analyzed retrospectively the PNS C-T scans(580 cases) that have been taken in patients with sinus-related symptoms. The incidence of
unilateral
MSH
was 5.3%(31 cases) and that of bilateral MSH was 5.0%(29 cases). In the unilateral cases of MSH, the volume estimate ratio to the normal side was 0.36-0.80(mean 0.61), and the in the bilateral cases, the volume estimate ratio to the normal
maxillary
sinus was 0.18-0.66(mean 0.45) on the right side and 0.21-0.68(mean 0.41) on the left side. The associated anatomical abnormalities included elevated canine fossa(100%), zygomatic pneumatization(48%), vertical enlargement of the orbit(32%),
caudal
or
lateral displacement of the infraorbital foramen(26%) and concave orbital floor(23%). It was also evident that the more severe MSH. The higher incidence of abnormalities is noted. We speculate that the complications during functional endoscopic
sinus
surgery(FESS) or Caldwell-Luc operation in patients with MSH can be minimized by careful assessment of these associated structural abnormalities.
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