title: Awake Craniotomy in Arteriovenous Malformation Surgery: The Usefulness of Cortical and Subcortical Mapping of Language Function in Selected Patients.
abstract: OBJECTIVE
  Awake craniotomy for removal of intra-axial lesions is a well-established procedure. Few studies, however, have investigated the usefulness of this approach for resection of arteriovenous malformations adjacent to eloquent language areas. We demonstrate our experience by using cortical stimulation mapping and report for the first time on the usefulness of subcortical stimulation with interrogation of language function during resection of arteriovenous malformations (AVMs) located near language zones.
  
  
  METHODS
  Patients undergoing awake craniotomy for AVMs located in language zones and at least 5 mm away from the closest functional magnetic resonance imaging activation were analyzed. During surgery, cortical bipolar stimulation at 50 Hz, with an intensity of 2 mA, increased to a maximum of 10 mA was performed in the region around the AVM before claiming it negative for language function. In positive language site, the area was restimulated 3 times to confirm the functional deficit. The AVM resection was started based on cortical mapping findings. Further subcortical stimulation performed in concert with speech interrogation by the neuropsychologist continued at key points throughout the resection as feasible. The usefulness of cortical and subcortical stimulation in addition to patient outcomes was analyzed.
  
  
  RESULTS
  Between March 2009 and September 2014, 42 brain AVM resections were performed. Four patients with left-sided language zone AVMs underwent awake craniotomy. The AVM locations were fronto-opercular in 2 patients and posterior temporal in 2. The AVM Spetzler-Martin grades were II (2 patients) and III (2 patients). In 1 patient, complete speech arrest was noticed during mapping of the peri-malformation zone, which was not breached during resection. In a second patient who initially demonstrated negative cortical mapping, a speech deficit was noticed during resection and subcortical stimulation. This guided the approach to protect and avoid the sensitive zone. This patient experienced mild postoperative expressive dysphasia that improved to normal within 6 weeks. Complete resection was achieved in all 4 patients. There were no other complications and no permanent neurological morbidity, resulting in good outcome in all 4 patients.
  
  
  CONCLUSIONS
  Language mapping, both cortical and subcortical during AVM resection, may be valuable in a very select group of AVMs in language zones. Defining safe margins and feedback to the surgeon may provide the highest chances of a surgical cure while minimizing the risk of incurring a language deficit.
authors.affiliation: Department of Neurosurgery, Cushing Neuroscience Institute, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, New York, USA. Electronic address: agamble@nshs.edu.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Gamble
authors.affiliation: Department of Neurology, Cushing Neuroscience Institute, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, New York, USA.
authors.forename: Sarah G
authors.initials: SG
authors.lastname: Schaffer
authors.affiliation: Department of Anesthesiology, North Shore University Hospital, Manhasset, New York, USA.
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Nardi
authors.affiliation: Department of Neurosurgery, Cushing Neuroscience Institute, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, New York, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Chalif
authors.affiliation: Department of Neurology, Cushing Neuroscience Institute, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, New York, USA.
authors.forename: Jeffery
authors.initials: J
authors.lastname: Katz
authors.affiliation: Department of Neurosurgery, Cushing Neuroscience Institute, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, New York, USA.
authors.forename: Amir R
authors.initials: AR
authors.lastname: Dehdashti
mesh_terms: D000328:Adult; D000368:Aged; D000758:Anesthesia; D001037:Aphasia / Q000209:etiology / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology / Q000601:surgery; D003198:Computer Simulation; D003399:Craniotomy / Q000379:methods*; D004558:Electric Stimulation; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D019635:Neurosurgical Procedures / Q000379:methods*; D018570:Risk Assessment; D013064:Speech Disorders / Q000209:etiology / Q000503:physiopathology; D014851:Wakefulness
keywords: Arteriovenous malformation; Awake craniotomy; Cortical mapping; Language; Subcortical stimulation