title: Transcranial Doppler and near-infrared spectroscopy can evaluate the hemodynamic effect of carotid artery occlusion.
abstract: OBJECTIVE
  Cerebral hemodynamic and metabolic changes can compensate for the decrease in cerebral blood flow occurring in patients with carotid occlusive disease. At present, a complete assessment of the cerebral adaptive status is only possible with positron-emission tomography. Near-infrared spectroscopy (NIRS) is a noninvasive technique that, providing a real time assessment of fluctuations in cerebral hemoglobin, has been used to estimate the cerebral blood volume and to measure cerebral vasomotor reactivity (VMR). Moreover, NIRS technology, by allowing the absolute measurement of absorption and scattering coefficients of brain, can determine the oxyhemoglobin and deoxyhemoglobin concentrations in situ in the blood stream.
  
  
  METHODS
  In order to evaluate different aspects of the cerebral hemodynamic status, 27 subjects with symptomatic and asymptomatic carotid artery occlusion and 30 healthy subjects underwent a simultaneous examination by means of transcranial Doppler (TCD), able to reliably detect collateral circulation and VMR, and NIRS at rest condition and during CO2 reactivity test.
  
  
  RESULTS
  The main finding of this study was the demonstration of a difference between asymptomatic and symptomatic patients in terms of mean flow velocity increase (52.4% versus 21.0%; P<0.001) estimated by TCD and of hemoglobin saturation increase measured by NIRS (6.8% versus 3.8%; P=0.015).
  
  
  CONCLUSIONS
  The opportunity to perform NIRS and TCD simultaneously provides useful information about both hemodynamic and metabolic cerebral adaptive status in patients with occlusive disease in a simple, noninvasive, and reliable way.
authors.affiliation: AFaR: Dipartimento di Neuroscienze, Ospedale San Giovanni Calibita Fatebenefratelli, Isola Tiberina 00186 Rome, Italy. fabriziovernieri@tin.it
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vernieri
authors.forename: Francesco
authors.initials: F
authors.lastname: Tibuzzi
authors.forename: Patrizio
authors.initials: P
authors.lastname: Pasqualetti
authors.forename: Nicola
authors.initials: N
authors.lastname: Rosato
authors.forename: Francesco
authors.initials: F
authors.lastname: Passarelli
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
authors.forename: Mauro
authors.initials: M
authors.lastname: Silvestrini
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation*; D002245:Carbon Dioxide; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007834:Lasers; D008297:Male; D010100:Oxygen / Q000378:metabolism; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D006454:Hemoglobins; D002245:Carbon Dioxide; D010100:Oxygen