title: Intraoperative confirmation of hand motor area identified preoperatively by magnetoencephalography.
abstract: BACKGROUND
  Presurgical functional mapping using magnetoencephalography (MEG) has been performed for somatosensory, auditory and visual functions; however, the traditional analysis method utilizing dipole source analysis has some inherent limitations when applied to the mapping of cortical motor areas. Recently, a novel source reconstruction algorithm [event-related synthetic aperture magnetometry (erSAM)] has demonstrated success for the localization of motor function in healthy adults. We applied this technique to preoperatively map motor function in a young patient. We then confirmed our mapping with direct cortical stimulation intraoperatively.
  
  
  METHODS
  This is a case report of an 8-year-old girl with right hand and arm weakness and poor right hand motor control secondary to a left peri-rolandic tumor. Preoperatively, whole-head MEG was recorded while the patient performed a self-paced button pressing task. Cortical activity associated with the onset of movement was localized to the right hand precentral gyrus superior and medial to the tumor using erSAM, while sensory function was localized posterior to the tumor on the postcentral gyrus.
  
  
  RESULTS
  Intraoperative direct cortical stimulation of the motor area identified by MEG resulted in electromyographic activation of intrinsic muscles of the contralateral hand exclusively.
  
  
  CONCLUSIONS
  This is the first report of a case where direct cortical stimulation has confirmed a motor cortical location identified by the erSAM method.
authors.affiliation: Division of Neurology, The Hospital for Sick Children, Toronto, Ont., Canada. elizabeth.pang@sickkids.ca
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Pang
authors.forename: James M
authors.initials: JM
authors.lastname: Drake
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otsubo
authors.forename: Allison
authors.initials: A
authors.lastname: Martineau
authors.forename: Samuel
authors.initials: S
authors.lastname: Strantzas
authors.forename: Douglas
authors.initials: D
authors.lastname: Cheyne
authors.forename: William
authors.initials: W
authors.lastname: Gaetz
mesh_terms: D001932:Brain Neoplasms / Q000150:complications / Q000601:surgery*; D002648:Child; D004558:Electric Stimulation; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006225:Hand / Q000294:innervation*; D006801:Humans; D015225:Magnetoencephalography; D016343:Monitoring, Intraoperative; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement