title: Accessing the recesses of the fourth ventricle: comparison of tonsillar retraction and resection in the telovelar approach.
abstract: OBJECTIVE
  To compare the effectiveness of the telovelar approach with tonsillar manipulation for approaching the recesses of the fourth ventricle.
  
  
  METHODS
  A telovelar approach was performed in 8 injected cadaveric heads. Areas of exposure were measured for the superolateral and lateral recesses. Horizontal angles were evaluated by targeting the cerebral aqueduct and medial margin of the lateral recess. Quantitative comparisons were made between the telovelar dissections and various tonsillar manipulations.
  
  
  RESULTS
  Tonsillar retraction provided a comparable exposure of the superolateral recess with tonsillar resection (26.4 +/- 17.6 vs 25.2 +/- 12.5 mm2, respectively; P = .825). Tonsillar resection significantly increased exposure of the lateral recess compared with tonsillar retraction (31.1 +/- 13.3 vs 20.2 +/- 11.5 mm2, respectively; P = .002). Compared with tonsillar retraction, the horizontal angle to the lateral recess increased after either contralateral tonsillar retraction (22.7 +/- 4.8 vs 36.7 +/- 6.5 degrees) or tonsillar resection (22.7 +/- 4.8 vs 31.5 +/- 7.6 degrees; all adjusted P < .01). The horizontal angle to the cerebral aqueduct increased significantly with tonsillar resection compared with tonsillar retraction (17.6 +/- 2.3 vs 13.2 +/- 2.8 degrees; P < .001)
  
  
  CONCLUSIONS
  Compared with tonsillar retraction, tonsillar resection provides a wider corridor to, and a larger area of exposure of, the cerebral aqueduct and lateral recess. Contralateral tonsillar retraction improves access to the lateral recess by widening the surgical view from the contralateral side.
authors.affiliation: Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA.
authors.forename: Pakrit
authors.initials: P
authors.lastname: Jittapiromsak
authors.forename: Hakan
authors.initials: H
authors.lastname: Sabuncuoglu
authors.forename: Pushpa
authors.initials: P
authors.lastname: Deshmukh
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
authors.forename: Mark C
authors.initials: MC
authors.lastname: Preul
mesh_terms: D002102:Cadaver; D002531:Cerebellum / Q000033:anatomy & histology / Q000601:surgery*; D002535:Cerebral Aqueduct / Q000033:anatomy & histology / Q000601:surgery; D002551:Cerebral Ventricle Neoplasms / Q000601:surgery*; D004210:Dissection / Q000379:methods; D020546:Fourth Ventricle / Q000033:anatomy & histology / Q000601:surgery*; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control; D019635:Neurosurgical Procedures / Q000379:methods*; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control; D012249:Rhombencephalon / Q000033:anatomy & histology / Q000601:surgery*; D014696:Ventriculostomy / Q000379:methods*