title: Intraoperative subcortical language tract mapping guides surgical removal of gliomas involving speech areas.
abstract: OBJECTIVE
  Subcortical stimulation can be used to identify functional language tracts during resection of gliomas located close to or within language areas or pathways. The objective of the present study was to investigate the feasibility of the routine use of subcortical stimulation for identification of language tracts in a large series of patients with gliomas and to determine the influence that subcortical language tract identification exerted on the extent of surgery and on the appearance of immediate and definitive postoperative deficits.
  
  
  METHODS
  Subcortical stimulation for language tract identification was systematically used during surgical removal of 88 gliomas (44 high-grade and 44 low-grade gliomas) involving language pathways. Procedures were performed during asleep/awake craniotomy. Subcortical stimulation was continuously alternated with surgical resection in a back-and-forth fashion. Language performances were tested by neuropsychological language evaluation preoperatively and at 3, 30, and 90 days after surgery.
  
  
  RESULTS
  Language tracts were identified in 59% of patients, with differences according to tumor location but not according to histological grade. Language tract identification influenced the ability to reach a complete tumor removal in low-grade gliomas, in which tracts were documented inside the peripheral mass of the tumor. Identification of language tracts was associated with a higher occurrence of transient postoperative deficits (67.3% of cases), but a low occurrence of definitive morbidity (2.3% of cases). A pattern of typical language disturbances related to the phonological and semantic system can be identified according to tumor location, with preservation being important for the maintenance of language integrity.
  
  
  CONCLUSIONS
  Our study supports the routine use of subcortical stimulation for language tract identification as a reliable tool for guiding surgical removal of gliomas in or in close proximity to language areas or pathways.
authors.affiliation: Department of Neurological Sciences, University of Milan, Milan, Italy. lorenzo.bello@unimi.it
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bello
authors.forename: Marcello
authors.initials: M
authors.lastname: Gallucci
authors.forename: Marica
authors.initials: M
authors.lastname: Fava
authors.forename: Giorgio
authors.initials: G
authors.lastname: Carrabba
authors.forename: Carlo
authors.initials: C
authors.lastname: Giussani
authors.forename: Francesco
authors.initials: F
authors.lastname: Acerbi
authors.forename: Pietro
authors.initials: P
authors.lastname: Baratta
authors.forename: Valeria
authors.initials: V
authors.lastname: Songa
authors.forename: Valeria
authors.initials: V
authors.lastname: Conte
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Branca
authors.forename: Nino
authors.initials: N
authors.lastname: Stocchetti
authors.forename: Costanza
authors.initials: C
authors.lastname: Papagno
authors.forename: Sergio Maria
authors.initials: SM
authors.lastname: Gaini
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000503:physiopathology / Q000601:surgery*; D002540:Cerebral Cortex / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D005910:Glioma / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D013060:Speech / Q000502:physiology*