title: Anatomy of the supraventricular portion of the pyramidal tract.
abstract: BACKGROUND
  The anatomy and somatotopy of the pyramidal tract during its course in the internal capsule has recently been discussed by many publications. However, the reports on the anatomy of the clinically more important supraventricular portion of the tract are scarce. The objective of this study is to investigate the anatomy and somatotopy of the supraventricular portion of the pyramidal tract.
  
  
  METHODS
  In 13 patients undergoing surgery with subcortical electric stimulation for tumors located in the supraventricular white matter close to the pyramidal tract (as depicted by diffusion tensor tracking [DTT]), the relationship between the position of the stimulation point and the motor response in the arm or leg was analyzed. Additionally, the somatotopic organization of the tract was studied using separate tracking of arm and leg fibers in 20 healthy hemispheres. Finally, the course of the tract was studied by dissecting 15 previously frozen human hemispheres.
  
  
  RESULTS
  In most cases, subcortical stimulation during the resection of tumors located behind and in front of the pyramidal tract elicited leg and arm movement, respectively. This association of stimulation point position with motor response type was significant. A DTT study of the somatotopy demonstrated a varying degree of rotation of the leg and arm fibers from mediolateral to posteroanterior configuration. Anatomic dissections demonstrated a folding-fan like structure of the pyramidal tract with a similar rotation pattern.
  
  
  CONCLUSIONS
  The pyramidal tract undergoes a large part of its rotation from mediolateral to posteroanterior configuration during its course in the supraventricular white matter, although interindividual differences exist.
authors.affiliation: Department of Neurosurgery, J.E. Purkinje University and Masaryk Hospital, Usti nad Labem, Czech Republic. amirzolal@gmail.com
authors.forename: Amir
authors.initials: A
authors.lastname: Zolal
authors.forename: Petr
authors.initials: P
authors.lastname: Vachata
authors.forename: Aleš
authors.initials: A
authors.lastname: Hejčl
authors.forename: Robert
authors.initials: R
authors.lastname: Bartoš
authors.forename: Alberto
authors.initials: A
authors.lastname: Malucelli
authors.forename: Martina
authors.initials: M
authors.lastname: Nováková
authors.forename: Milouš
authors.initials: M
authors.lastname: Derner
authors.forename: Martin
authors.initials: M
authors.lastname: Sameš
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000601:surgery; D056324:Diffusion Tensor Imaging / Q000379:methods*; D006801:Humans; D020772:Internal Capsule / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D009445:Neuroanatomy / Q000379:methods*; D011712:Pyramidal Tracts / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D012189:Retrospective Studies