title: Validation of a magnetic resonance imaging guided stereotactic access to the ovine brainstem.
abstract: BACKGROUND
  Anatomical differences between humans and domestic mammals preclude the use of reported stereotactic approaches to the brainstem in animals. In animals, brainstem biopsies are required both for histopathological diagnosis of neurological disorders and for research purposes. Sheep are used as a translational model for various types of brain disease and therefore a species-specific approach needs to be developed. The aim of the present study was to establish a minimally invasive, accurate and reproducible stereotactic approach to the brainstem of sheep, using the magnetic resonance imaging guided BrainsightTM frameless stereotactic system.
  
  
  RESULTS
  A transoccipital transcerebellar approach with an entry point in the occipital bone above the vermis between the transverse sinus and the external occipital protuberance was chosen. This approach provided access to the target site in all heads. The overall mean needle placement error was 1.85 ± 1.22 mm.
  
  
  CONCLUSIONS
  The developed transoccipital transcerebellar route is short, provides accurate access to the ovine caudal cranial fossa and is a promising approach to be further assessed in live animals.
authors.forename: Anne
authors.initials: A
authors.lastname: Staudacher
authors.forename: Anna
authors.initials: A
authors.lastname: Oevermann
authors.forename: Michael H
authors.initials: MH
authors.lastname: Stoffel
authors.affiliation: Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Berne, Längassstrasse 128, Berne, CH 3012, Switzerland. daniela.gorgas@vetsuisse.unibe.ch.
authors.forename: Daniela
authors.initials: D
authors.lastname: Gorgas
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D011859:Radiography; D012756:Sheep / Q000033:anatomy & histology*; D013238:Stereotaxic Techniques / Q000662:veterinary*