title: Detection of cerebral ischemia in neurovascular surgery using quantitative frequency-domain near-infrared spectroscopy.
abstract: OBJECTIVE
  There is great value in monitoring for signs of ischemia during neurovascular procedures. Current intraoperative monitoring techniques provide real-time feedback with limited accuracy. Quantitative frequency-domain near-infrared spectroscopy (Q-NIRS) allows measurement of tissue oxyhemoglobin (HbO2), deoxyhemoglobin (HHb), and total hemoglobin (tHb) concentrations and brain tissue oxygen saturation (SO2), which could be useful when monitoring for evidence of intraoperative ischemia.
  
  
  METHODS
  Using Q-NIRS, the authors monitored 25 neurovascular procedures including aneurysm clip placement, arteriovenous malformation resection, carotid endarterectomy, superficial temporal artery-middle cerebral artery (MCA) bypass surgery, external carotid artery-MCA bypass surgery, encephaloduromyosynangiosis, and balloon occlusion testing. The Q-NIRS technology provides measurable cerebral oxygenation values independent from those of the scalp tissue. Thus, alterations in the variables measured with Q-NIRS quantitatively reflect cerebral tissue perfusion. Bilateral monitoring was performed in all cases. Five of the patients exhibited evidence of clinical ischemic events during the procedures. One patient suffered blood loss with systemic hypotension and developed diffuse brain edema intraoperatively, one patient suffered an ischemic event intraoperatively and developed an occipital stroke postoperatively, and one patient showed slowing on electroencephalography intraoperatively during carotid clamping; in two patients balloon occlusion testing failed. In all cases of ischemic events occurring during the procedure, Q-NIRS monitoring showed a decrease in HbO2, tHb, and SO2, and an increase in HHb.
  
  
  CONCLUSIONS
  . Quantitative frequency-domain near-infrared spectroscopy provides quantifiable and continuous real-time information about brain oxygenation and hemodynamics in a noninvasive manner. This continuous intraoperative oxygenation monitoring is a promising method for detecting ischemic events during neurovascular procedures.
authors.affiliation: Department of Neurosurgery, University of Illinois at Chicago Medical Center, Chicago 60612, USA.
authors.forename: Mateo
authors.initials: M
authors.lastname: Calderon-Arnulphi
authors.forename: Ali
authors.initials: A
authors.lastname: Alaraj
authors.forename: Sepideh
authors.initials: S
authors.lastname: Amin-Hanjani
authors.forename: William W
authors.initials: WW
authors.lastname: Mantulin
authors.forename: Chiara M
authors.initials: CM
authors.lastname: Polzonetti
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Fady T
authors.initials: FT
authors.lastname: Charbel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D010092:Oximetry; D010100:Oxygen / Q000378:metabolism; D011237:Predictive Value of Tests; D019265:Spectroscopy, Near-Infrared; D014656:Vascular Surgical Procedures / Q000009:adverse effects*
chemical_list: D006454:Hemoglobins; D010100:Oxygen