Enlargement of the infraorbital canal following Caldwell-Luc surgery.

Abstract

The infraorbital canal (IOC), which runs in the roof of the maxillary sinus, is a useful anatomical landmark for the infraorbital nerve (ION) on computed tomography (CT) images. Enlargement of the IOC on CT images is thought to be a pathological state that usually affects the ION. However, we have frequently observed enlargement of the IOC in patients with a history of radical surgery of the maxillary sinus: so-called Caldwell-Luc (CL) surgery. In this study, the size of the IOC of the maxillary sinus was compared between patients with a history of CL surgery (post-CL IOCs) and those with no history of CL surgery (control IOCs). A total of 347 consecutive patients who underwent facial CT from January 2014 to October 2014 for various indications were evaluated. After excluding groove-type IOCs and IOCs with pathological lesions that could affect their diameters, 47 post-CL IOCs in 26 patients were finally compared with 504 control IOCs in 252 patients. To evaluate IOC size, the short-axis diameter of the IOC was measured on a reconstructed coronal image at the level of the posterior pole of the eyeball. The short-axis diameters of the post-CL IOCs and control IOCs were 3.0±0.6 and 1.4±0.3mm, respectively (p<0.005). The short-axis diameters of post-CL IOCs are significantly enlarged (approximately double the diameter) compared to those of control IOCs.