title: Endoscopic endonasal transmaxillary approach and endoscopic sublabial transmaxillary approach: surgical decision-making and implications of the nasolacrimal duct.
abstract: BACKGROUND
  The nasolacrimal duct resides in the wall of the medial nasal cavity and influences minimal access endoscopic transmaxillary approaches to the lateral skull base. We describe an algorithm for surgical approach selection on the basis of the relationship of the target lesion to a line drawn from the anterior nasal SEptum through the Nasolacrimal Duct to the lesion (i.e., SEND line).
  
  
  METHODS
  We use the SEND line to estimate the lateral extent in the endonasal middle meatal transmaxillary approach, where the surgeon has good surgical freedom without the use of angled instruments and endoscopes. Lesions with an epicenter lateral to the SEND line were addressed through a sublabial anterior antrostomy transmaxillary corridor. Tumors with a more medially located epicenter, such as those involving the lateral sphenoid sinus and pterygoid plates, were addressed through the endonasal middle meatal corridor. Extensive tumors involving both domains were addressed through a combination approach.
  
  
  RESULTS
  We describe three instructive cases in which the approach selection was determined in part by preoperative assessment of the location of the tumor relative to the SEND line.
  
  
  CONCLUSIONS
  The endoscopic sublabial transmaxillary and endoscopic endonasal middle meatal transmaxillary approaches are complementary corridors to the anterior skull base that can be used independently or in combination. The location of the target lesion relative to the SEND line as determined on preoperative imaging can serve as a guide for surgical decision making.
authors.affiliation: Barrow Neurological Institute, Division of Neurological Surgery, St Joseph's Hospital and Medical Center, Phoenix, Arizona, USA. Electronic address: andrew.little@bnaneuro.net.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Little
authors.forename: Peter
authors.initials: P
authors.lastname: Nakaji
authors.forename: John
authors.initials: J
authors.lastname: Milligan
mesh_terms: D000328:Adult; D000465:Algorithms; D018322:Angiofibroma / Q000000981:diagnostic imaging / Q000601:surgery; D002675:Child, Preschool; D002817:Chordoma / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging / Q000601:surgery; D008875:Middle Aged; D009208:Myoepithelioma / Q000000981:diagnostic imaging / Q000601:surgery; D009296:Nasal Cavity / Q000000981:diagnostic imaging / Q000601:surgery; D009301:Nasolacrimal Duct / Q000000981:diagnostic imaging / Q000601:surgery*; D044583:Neuroendoscopy / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods*; D009669:Nose Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D019291:Skull Base / Q000000981:diagnostic imaging / Q000601:surgery; D019292:Skull Base Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*