title: Prelemniscal Radiations: A New Reliable Landmark of the Thalamic Nucleus Ventralis Intermedius Location.
abstract: BACKGROUND
  The thalamic nucleus ventralis intermedius (Vim nucleus) is the main surgical target for the management of intractable tremor. The Vim nucleus cannot be reliably located with routine stereotactic imaging, and so targeting relies on indirect coordinates.
  
  
  OBJECTIVE
  We propose to investigate if colored fractional anisotropy (FA) mapping can help to locate the Vim nucleus by identifying its borders, particularly the prelemniscal radiations (Raprl) that lie below and behind the nucleus.
  
  
  METHODS
  We retrospectively reviewed the colored FA maps for 18 consecutive patients having undergone gamma knife stereotactic Vim thalamotomy for disabling tremor.
  
  
  RESULTS
  The Raprl were easily located on colored FA maps and enabled the identification of the lower and posterior borders of the Vim nucleus in all patients. In the medial plane, the mean distance ± SD between the Raprl and Vim nucleus was 0.77 ± 1.19 mm (range: 0.1-3.3). The Raprl were located 1.35 ± 1.33 mm (range: 0.2-3.9) behind the Vim nucleus and 1.99 ± 1.23 mm (range: 0.7-4.4) below it. The mean vector distance ± SD between the Vim nucleus and the Raprl was 3 ± 1.38 mm (range: 1.25-5.2).
  
  
  CONCLUSIONS
  The Raprl can be easily seen on colored FA maps and constitute a reliable landmark for the borders of the Vim nucleus.
authors.affiliation: Department of Neurosurgery, Amiens-Picardie University Hospital, Amiens, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Lefranc
authors.forename: Romain
authors.initials: R
authors.lastname: Carron
authors.forename: Jean
authors.initials: J
authors.lastname: Regis
mesh_terms: D001931:Brain Mapping / Q000379:methods; D006801:Humans; D010300:Parkinson Disease / Q000601:surgery*; D016634:Radiosurgery; D012189:Retrospective Studies; D014202:Tremor / Q000601:surgery*; D020651:Ventral Thalamic Nuclei / Q000601:surgery*