title: Neuronavigational endoscopic endonasal sellar and parasellar surgery using a 2-mm-diameter lens rigid-rod endoscope: a cadaver study.
abstract: OBJECTIVE
  Most of the endoscopes used for endonasal transsphenoidal surgery use 4-mm diameter lenses. The applicability of a newly developed neuroendoscope with a lens diameter of only 2 mm was tested in endonasal transsphenoidal pituitary surgery.
  
  
  METHODS
  The newly developed rigid-rod neuroendoscope with a 2-mm lens and an endoscope with a 4-mm lens were coupled with a navigation system and used for this comparative study. Comparison between the views obtained with these two devices was performed in a model and in formalin-fixed cadaver heads. A pure endonasal approach was used to reach and explore the sellar and parasellar regions. The navigation system was used to locate the same position in both lenses for image comparison.
  
  
  RESULTS
  The sellar and parasellar regions could be reached and explored using the new endoscope with the 2-mm lens and an oval-shaped irrigation and suction channel. The visual field appeared to be reduced compared with that of the 4-mm lens. However, this reduction was compensated by greater mobility and easier introduction and maneuvering of the instruments at the sellar level. Reduced image size and brightness were also found using the 2-mm lens compared with the 4-mm lens. These differences could be overcome by increasing the amount of light and enlarging the image but with subsequent reduction in image resolution.
  
  
  CONCLUSIONS
  The small diameter of this neuroendoscope resulted in good maneuverability and maintained a fine quality of vision. Children and patients with small nostrils are good candidates for the use of such a device.
authors.affiliation: Department of Neurosurgery, International Neuroscience Institute, Hannover, Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Di Rocco
authors.forename: Shizuo
authors.initials: S
authors.lastname: Oi
authors.forename: Amir
authors.initials: A
authors.lastname: Samii
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Paternó
authors.forename: Günther C
authors.initials: GC
authors.lastname: Feigl
authors.forename: Wolf
authors.initials: W
authors.lastname: Lüdemann
authors.forename: Madjid
authors.initials: M
authors.lastname: Samii
mesh_terms: D002102:Cadaver; D019723:Endoscopes / Q000592:standards; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000601:surgery*; D038361:Neuronavigation / Q000295:instrumentation*; D019635:Neurosurgical Procedures / Q000295:instrumentation*; D010902:Pituitary Gland / Q000601:surgery; D012658:Sella Turcica / Q000033:anatomy & histology / Q000601:surgery*