title: Microanatomy of endoscope-assisted glabellar nasal keyhole approach.
abstract: OBJECTIVE
  To make a study of the detailed microanatomy of endoscope-assisted glabellar nasal keyhole approach (GNKA) to be used clinically.
  
  
  METHODS
  10 dry adult Chinese skulls were measured and 10 perfused cadaveric heads were dissected to mimic the GNKA.
  
  
  RESULTS
  Average distances between bilateral supraorbital foramen/incisure, supratrochlear incisure, medial orbital wall were 47.71+/-3.61 mm, 33.67+/-3.82 mm and 24.34+/-1.29 mm, respectively, in dry skulls. Average distance from nasion to medial inter-canthus line (ICL) was 10.31+/-1.02 mm in cadaveric heads. The nasion was 3.95+/-0.45 mm above the cribriform plate (CP) and the ICL is 6.25+/-0.71 mm below. With the assistance of endoscopes, GNKA can expose all extradural structures near the midline from the anterior skull base to the ventral brain stem corresponding to the clivus. The exposed clival dura was 19.18+/-1.44 mm in width and 25.44+/-1.25 mm in length. Intradural structures such as frontal base, parasellar area, longitudinal fissure and the third ventricle floor, can also be exposed.
  
  
  CONCLUSIONS
  GNKA is a minimally invasive and effective anterior skull base approach. Determining the inferior margin of incision by ICL instead of nasion is more convenient and can expose the subcranial area better.
authors.affiliation: Department of Neurosurgery, Shanghai Second Medical, University Affiliated Renji Hospital, Shanghai, PR China.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.forename: Y
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000328:Adult; D002102:Cadaver; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D009296:Nasal Cavity / Q000033:anatomy & histology* / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D019291:Skull Base / Q000033:anatomy & histology / Q000601:surgery