The clinical landmark of infraorbital foramen in Chinese population: a prospective measurement study

Background Infraorbital nerve block can only be administered effectively with good knowledge of the location of the infraorbital foramen (IOF). In this article, we will describe the clinical landmark of the IOF with references to the infraorbital rim (IOR), mid-pupillary line (MPL), and facial midline (FML). Methods In our division, maxillary swing approach was adopted for the access of the nasopharynx and skull base. Through a Weber-Ferguson-Longmire incision, the maxilla was freed from its bony connections and swung out to expose the skull base. With this approach, the infraorbital foramen and nerve were identified under direct vision. Prospective measurements were taken intraoperatively on a series of patients who underwent maxillary swing operation. The distances between the IOF and various reference points (IOR, MPL, and FML) were measured with caliper. Means, standard deviations, and ranges were determined. Results From April 2009 to October 2012, 30 patients were included in this study. The locations of 30 infraorbital foramina were analyzed. The distances between IOF and IOR, MPL, and FML ranged from 8 to 12 (mean 9.6 ± 1.3) mm, 4 to 14 (mean 9.3 ± 2.4) mm, and 24 to 38 (mean 32.7 ± 3.4) mm, respectively. Conclusions To our knowledge, this is the first study in the literature demonstrating the clinical landmark of IOF on living persons and adopting MPL as a reference point. We believe that the IOR and MPL are convenient reference points for the accurate localization of IOF. Level of Evidence: Level IV, diagnostic study.