title: Effect of brain surgery on auditory and motor cortex activation: a preliminary functional magnetic resonance imaging study.
abstract: OBJECTIVE
  The effect of glioma removal on blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) activation has not been widely documented. The aim of this preliminary study was to observe the effect of tumor resection on BOLD fMRI of the auditory and motor cortices.
  
  
  METHODS
  Seven patients with gliomas underwent preoperative and early postoperative BOLD fMRI, and five of them underwent additional late postoperative BOLD fMRI. The auditory and motor cortices were localized with activation studies. A hemispheric activation index was used to quantify the relative extent of BOLD activation.
  
  
  RESULTS
  The resection of a glioma with preoperative edema resulted in an increase from the preoperative to the early postoperative fMRI on auditory BOLD activation on the side of the tumor compared with the contralateral side. The same phenomenon was observed in one patient with motor BOLD activation. However, when no preoperative edema was present, a transient decrease in relative auditory BOLD activation was found.
  
  
  CONCLUSIONS
  The results of this study suggest that the resection of a glioma with preoperative edema affecting the auditory and/or motor cortex may cause a transient increase in the BOLD response ipsilateral to the tumor. It seems that when the tumor is resected, the pressure on the brain, specifically on the affected auditory and/or motor cortex, decreases and the functional cortex becomes more easily detectable in BOLD fMRI.
authors.affiliation: Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland. salla-maarit.kokkonen@ppshp.fi
authors.forename: Salla-Maarit
authors.initials: SM
authors.lastname: Kokkonen
authors.forename: Vesa
authors.initials: V
authors.lastname: Kiviniemi
authors.forename: Minna
authors.initials: M
authors.lastname: Mäkiranta
authors.forename: Sanna
authors.initials: S
authors.lastname: Yrjänä
authors.forename: John
authors.initials: J
authors.lastname: Koivukangas
authors.forename: Osmo
authors.initials: O
authors.lastname: Tervonen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001303:Auditory Cortex / Q000098:blood supply*; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery*; D005260:Female; D005910:Glioma / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000098:blood supply*; D019635:Neurosurgical Procedures / Q000379:methods*; D010100:Oxygen / Q000097:blood; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010100:Oxygen