title: Amplitude of Tissue Oxygenation Index Change Predicts Cerebral Hyperperfusion Syndrome During Carotid Artery Stenting.
abstract: OBJECTIVE
  Hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) is a rare but serious complication. HPS is associated with preoperative hemodynamic impairment as the result of poor collateral flow and intraoperative cerebral ischemia. Filter-type embolic protection devices maintain anterograde carotid flow during CAS and prevent HPS somewhat. The early treatment of patients undergoing CAS and at risk for HPS is essential. Near-infrared spectroscopy allows noninvasive, real-time measurement of frontal lobe regional cerebral O2saturation (TOI; tissue oxygenation index).
  
  
  METHODS
  The perioperative amplitude of TOI was monitored in 130 patients undergoing CAS while using a filter-type embolic protection device. Patients were divided retrospectively into good (n = 110) and poor/no crossflow groups (n = 20), and we compared the amplitude of the TOI change, correlation with ipsilateral regional cerebral blood flow, and clinical results.
  
  
  RESULTS
  The incidence of HPS was significantly greater in the poor/no crossflow group (P = 0.019). In 2 patients with HPS, the amplitude of the TOI change was V-shaped, with a decrease after postdilatation and an increase above baseline 5 minutes after reperfusion. The TOI/baseline ratio was significantly decreased after internal carotid artery occlusion for postdilatation in the ipsilateral hemisphere in the poor/no crossflow group (P < 0.05). Significant linear correlations were observed between TOI/baseline ratio changes and preoperative cerebrovascular reactivity and the postoperative asymmetry index (r = -0.346, P = 0.002, r = 0.613, P < 0.001, respectively).
  
  
  CONCLUSIONS
  The amplitude of the TOI change measured by near-infrared spectroscopy was an excellent predictor of cerebral HPS after CAS.
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan.
authors.forename: Hun Soo
authors.initials: HS
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan. Electronic address: nakagawa@nmu-gw.naramed-u.ac.jp.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakagawa
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Yokoyama
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Motoyama
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan.
authors.forename: Young Su
authors.initials: YS
authors.lastname: Park
authors.affiliation: Department of Radiology, Nara Medical University, Nara, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Wada
authors.affiliation: Department of Radiology, Nara Medical University, Nara, Japan.
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
authors.affiliation: Department of Neurosurgery, Nara Medical University, Nara, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakase
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000601:surgery*; D002560:Cerebrovascular Circulation; D057510:Endovascular Procedures; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D019265:Spectroscopy, Near-Infrared; D015607:Stents; D013577:Syndrome; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D010100:Oxygen
keywords: Carotid artery stenting; Hyperperfusion syndrome; Near-infrared spectroscopy