Axial Sections of Brainstem Safe Entry Zones and Clinical Importance of Intrinsic Structures: A Review

Inci S., Baylarov B.

World Neurosurgery, vol.185, pp.171-180, 2024 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Review
  • Volume: 185
  • Publication Date: 2024
  • Doi Number: 10.1016/j.wneu.2024.02.088
  • Journal Name: World Neurosurgery
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, CAB Abstracts, Index Islamicus, MEDLINE, Veterinary Science Database
  • Page Numbers: pp.171-180
  • Keywords: Brainstem, Cavernoma, Microanatomy, Safe entry zone, Tumor
  • Hacettepe University Affiliated: Yes


Brainstem surgery is more difficult and riskier than surgeries in other parts of the brain due to the high density of critical tracts and cranial nerves nuclei in this region. For this reason, some safe entry zones into the brainstem have been described. The main purpose of this article is to bring on the agenda the significance of the intrinsic structures of the safe entry zones to the brainstem. Having detailed information about anatomic localization of these sensitive structures is important to predict and avoid possible surgical complications. In order to better understand this complex anatomy, we schematically drew the axial sections of the brainstem showing the intrinsic structures at the level of 9 safe entry zones that we used, taking into account basic neuroanatomy books and atlases. Some illustrations are also supported with intraoperative pictures to provide better surgical orientation. The second purpose is to remind surgeons of clinical syndromes that may occur in case of surgical injury to these delicate structures. Advanced techniques such as tractography, neuronavigation, and neuromonitorization should be used in brainstem surgery, but detailed neuroanatomic knowledge about safe entry zones and a meticulous surgery are more important. The axial brainstem sections we have drawn can help young neurosurgeons better understand this complex anatomy.