title: Laser speckle imaging identification of increases in cortical microcirculatory blood flow induced by motor activity during awake craniotomy.
abstract: OBJECTIVE
  The goal of awake neurosurgery is to maximize resection of brain lesions with minimal injury to functional brain areas. Laser speckle imaging (LSI) is a noninvasive macroscopic technique with high spatial and temporal resolution used to monitor changes in capillary perfusion. In this study, the authors hypothesized that LSI can be useful as a noncontact method of functional brain mapping during awake craniotomy for tumor removal. Such a modality would be an advance in this type of neurosurgery since current practice involves the application of invasive intraoperative single-point electrocortical (electrode) stimulation and measurements.
  
  
  METHODS
  After opening the dura mater, patients were woken up, and LSI was set up to image the exposed brain area. Patients were instructed to follow a rest-activation-rest protocol in which activation consisted of the hand-clenching motor task. Subsequently, exposed brain areas were mapped for functional motor areas by using standard electrocortical stimulation (ECS). Changes in the LSI signal were analyzed offline and compared with the results of ECS.
  
  
  RESULTS
  In functional motor areas of the hand mapped with ECS, cortical blood flow measured using LSI significantly increased from 2052 ± 818 AU to 2471 ± 675 AU during hand clenching, whereas capillary blood flow did not change in the control regions (areas mapped using ECS with no functional activity).
  
  
  CONCLUSIONS
  The main finding of this study was that changes in laser speckle perfusion as a measure of cortical microvascular blood flow when performing a motor task with the hand relate well to the ECS map. The authors have shown the feasibility of using LSI for direct visualization of cortical microcirculatory blood flow changes during neurosurgery.
authors.affiliation: Department of Intensive Care, Erasmus MC University Medical Center, Rotterdam, The Netherlands. e.klijn@erasmusmc.nl
authors.forename: Eva
authors.initials: E
authors.lastname: Klijn
authors.forename: Hester C
authors.initials: HC
authors.lastname: Hulscher
authors.forename: Rutger K
authors.initials: RK
authors.lastname: Balvers
authors.forename: Wim P J
authors.initials: WP
authors.lastname: Holland
authors.forename: Jan
authors.initials: J
authors.lastname: Bakker
authors.forename: Arnaud J P E
authors.initials: AJ
authors.lastname: Vincent
authors.forename: Clemens M F
authors.initials: CM
authors.lastname: Dirven
authors.forename: Can
authors.initials: C
authors.lastname: Ince
mesh_terms: D000328:Adult; D001254:Astrocytoma / Q000601:surgery; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods; D001932:Brain Neoplasms / Q000601:surgery; D002540:Cerebral Cortex / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003399:Craniotomy; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D007834:Lasers; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D009043:Motor Activity / Q000502:physiology*; D019635:Neurosurgical Procedures; D009837:Oligodendroglioma / Q000601:surgery; D011446:Prospective Studies; D014851:Wakefulness / Q000502:physiology