title: Protrusion of the Infraorbital Nerve into the Maxillary Sinus on CT: Prevalence, Proposed Grading Method, and Suggested Clinical Implications.
abstract: OBJECTIVE
  The infraorbital nerve arises from the maxillary branch of the trigeminal nerve and normally traverses the orbital floor in the infraorbital canal. Sometimes, however, the infraorbital canal protrudes into the maxillary sinus separate from the orbital floor. We systematically studied the prevalence of this variant.
  
  
  METHODS
  We performed a retrospective review of 500 consecutive sinus CTs performed at our outpatient centers. The infraorbital nerve protruded into the maxillary sinus if the entire wall of the infraorbital canal was separate from the walls of the sinus. We recorded the length of the bony septum that attached the infraorbital canal to the wall of the maxillary sinus and noted whether the protrusion was bilateral. We also measured the distance from the inferior orbital rim where the infraorbital canal begins to protrude into the sinus.
  
  
  RESULTS
  There was a prevalence of 10.8% for infraorbital canal protrusion into the maxillary sinus and 5.6% for bilateral protrusion. The median length of the bony septum attaching the infraorbital canal to a maxillary sinus wall, which was invariably present, was 4 mm. The median distance at which the infraorbital nerve began to protrude into the sinus was 11 mm posterior to the inferior orbital rim.
  
  
  CONCLUSIONS
  Although this condition has been reported in only 3 patients previously, infraorbital canal protrusion into the maxillary sinus was present in >10% of our cohort. Identification of this variant on CT could help a surgeon avoid patient injury.
authors.affiliation: From the Departments of Radiology (J.E.L., A.G., J.L.C., R.D.Z., C.D.P.) jol9057@med.cornell.edu.
authors.forename: J E
authors.identifier: http://orcid.org/0000-0003-4323-7828
authors.initials: JE
authors.lastname: Lantos
authors.affiliation: Otolaryngology (A.N.P.), Weill Cornell Medical College, New York, New York.
authors.forename: A N
authors.initials: AN
authors.lastname: Pearlman
authors.affiliation: From the Departments of Radiology (J.E.L., A.G., J.L.C., R.D.Z., C.D.P.).
authors.forename: A
authors.identifier: http://orcid.org/0000-0003-2816-0340
authors.initials: A
authors.lastname: Gupta
authors.affiliation: From the Departments of Radiology (J.E.L., A.G., J.L.C., R.D.Z., C.D.P.).
authors.forename: J L
authors.identifier: http://orcid.org/0000-0002-6146-2191
authors.initials: JL
authors.lastname: Chazen
authors.affiliation: From the Departments of Radiology (J.E.L., A.G., J.L.C., R.D.Z., C.D.P.).
authors.forename: R D
authors.initials: RD
authors.lastname: Zimmerman
authors.affiliation: Department of Radiology (D.R.S.), Lenox Hill Hospital, New York, New York.
authors.forename: D R
authors.initials: DR
authors.lastname: Shatzkes
authors.affiliation: From the Departments of Radiology (J.E.L., A.G., J.L.C., R.D.Z., C.D.P.).
authors.forename: C D
authors.initials: CD
authors.lastname: Phillips
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008442:Maxillary Nerve / Q000002:abnormalities* / Q000000981:diagnostic imaging; D008443:Maxillary Sinus / Q000000981:diagnostic imaging*; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed