title: Preoperative localization of hand motor cortex by adaptive spatial filtering of magnetoencephalography data.
abstract: OBJECTIVE
  The goal of this study was to examine the sensitivity and specificity in preoperative localization of hand motor cortex by imaging regional event-related desynchronization (ERD) of brainwaves in the beta frequency band (15-25 Hz) involved in self-paced movement.
  
  
  METHODS
  Using magnetoencephalography (MEG), the authors measured ERD that occurred before self-paced unilateral index finger flexion in 66 patients with brain tumors, epilepsy, and arteriovenous malformations.
  
  
  RESULTS
  The authors applied an adaptive spatial filtering algorithm to MEG data and found that peaks of the tomographic distribution of beta-band ERD sources reliably localized hand motor cortex compared with electrical cortical stimulation. They also observed high specificity in estimating contralateral hand motor cortical representations relative to somatosensory cortex. Neither presence nor location of tumor changed the qualitative or quantitative location of motor cortex relative to somatosensory cortex.
  
  
  CONCLUSIONS
  An imaging protocol using ERD obtained by adaptive spatial filtering of MEG data can be used for extremely reliable preoperative localization of hand motor cortex.
authors.affiliation: Biomagnetic Imaging Laboratory, Department of Radiology, University of California, San Francisco, California 94143-0628, USA. sri@radiology.ucsf.edu
authors.forename: Srikantan
authors.initials: S
authors.lastname: Nagarajan
authors.forename: Heidi
authors.initials: H
authors.lastname: Kirsch
authors.forename: Peter
authors.initials: P
authors.lastname: Lin
authors.forename: Anne
authors.initials: A
authors.lastname: Findlay
authors.forename: Susanne
authors.initials: S
authors.lastname: Honma
authors.forename: Mitchel S
authors.initials: MS
authors.lastname: Berger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000601:surgery*; D002648:Child; D019054:Evoked Potentials, Motor; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000592:standards*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement; D011300:Preoperative Care / Q000592:standards*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013003:Somatosensory Cortex / Q000502:physiology