title: Surgical management of World Health Organization Grade II gliomas in eloquent areas: the necessity of preserving a margin around functional structures.
abstract: OBJECTIVE
  Recent surgical studies have demonstrated that the extent of resection is significantly correlated with median survival in WHO Grade II gliomas. Consequently, thanks to advances in intraoperative functional mapping, the authors questioned whether it is actually necessary to leave a "security" margin around eloquent structures.
  
  
  METHODS
  The authors first reviewed the classic literature, especially that based on epilepsy surgery and functional neuroimaging techniques, which led them to propose the rule of a security margin. Second, they detailed new developments in the field of intrasurgical electrical mapping, especially with regard to subcortical stimulation of the projection and long-distance association pathways. On the basis of these advances, the removal of gliomas according to functional boundaries has recently been suggested, with no margin around eloquent structures.
  
  
  RESULTS
  Comparative results showed that the rate of permanent deficit was similar with or without a security margin, that is, < 2%. However, a higher rate of transient neurological worsening in the immediate postsurgical period was associated with the absence of a margin, with recovery following adapted rehabilitation. On the other hand, the extent of resection was in essence improved with no margin.
  
  
  CONCLUSIONS
  This no-margin technique, based on the subpial dissection, and the repetition of both cortical and subcortical stimulation to preserve eloquent cortex as well as the white matter tracts (U-fibers, projection pathways, and long-distance connectivity) allow optimization of the extent of resection while preserving the quality of life (despite transitory impairment) thanks to mechanisms of brain plasticity.
authors.affiliation: Department of Neurosurgery, Hospital Quiron, 28223 Pozuelo de Alarcón, Madrid, Spain. santigilrob@yahoo.es
authors.forename: Santiago
authors.initials: S
authors.lastname: Gil-Robles
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
mesh_terms: D001921:Brain / Q000473:pathology* / Q000502:physiology / Q000601:surgery; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology* / Q000601:surgery*; D004292:Dominance, Cerebral / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005910:Glioma / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D019635:Neurosurgical Procedures / Q000379:methods; D015996:Survival Rate; D014851:Wakefulness / Q000502:physiology; D014944:World Health Organization