title: Comparative analysis of the retrosigmoid and lateral supracerebellar infratentorial approaches along the lateral surface of the pontomesencephalic junction: a different perspective.
abstract: OBJECTIVE
  To quantitatively assess the working distance and angle of attack among the retrosigmoid (RS), lateral supracerebellar (LS), and extreme lateral supracerebellar (EL) views on the lateral surface of the pontomesencephalic junction.
  
  
  METHODS
  Eight sides of silicone-injected fixed cadaveric heads were dissected using the three approaches. All predetermined anatomic points were collected by use of a frameless stereotactic device. The length of exposure and the angle of attack were calculated and compared. Predissection imaging was obtained for illustration.
  
  
  RESULTS
  The LS and EL approaches created a horizontal working space as compared with the vertical working space created by the RS approach. The RS view gained less posterior exposure margin than the LS and EL views (posterosuperior margin values: RS, 4.3 +/- 1.7 mm; LS, 6.4 +/- 2.0 mm; EL, 7.3 +/- 2.0 mm; P < 0.001; posteroinferior margin: RS, 2.7 +/- 2.7 mm; LS, 4.9 +/- 2.8 mm; EL, 8.3 +/- 2.5 mm; P < 0.001). When the tentorium is intact, transverse sinus retraction significantly accentuates the field of view by the EL approach compared with the LS approach at both the anteroinferior (P < 0.05) and posteroinferior (P < 0.001) margins. Between the supracerebellar types, the vertical angle of attack was significantly improved and the horizontal angle was significantly decreased when complete venous retraction was performed.
  
  
  CONCLUSIONS
  The supracerebellar views offer greater advantage over the RS view when the surgeon is working more posteriorly on the pontomesencephalic junction. Between the supracerebellar views, venous retraction creates a significantly wider vertical angle and also improves the exposure when the surgeon is working more inferiorly.
authors.affiliation: Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Pakrit
authors.initials: P
authors.lastname: Jittapiromsak
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Little
authors.forename: Pushpa
authors.initials: P
authors.lastname: Deshmukh
authors.forename: Peter
authors.initials: P
authors.lastname: Nakaji
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
authors.forename: Mark C
authors.initials: MC
authors.lastname: Preul
mesh_terms: D001933:Brain Stem / Q000033:anatomy & histology* / Q000601:surgery*; D002531:Cerebellum / Q000033:anatomy & histology* / Q000601:surgery*; D006801:Humans; D008636:Mesencephalon / Q000033:anatomy & histology* / Q000601:surgery*; D008953:Models, Anatomic; D019635:Neurosurgical Procedures / Q000379:methods*