title: Near-infrared Spectroscopy to Assess Cerebral Perfusion during Head-up Tilt-table Test in Patients with Syncope.
abstract: OBJECTIVE
  Neurocardiogenic syncope (NCS) is the most common cause of syncope in children and adolescents. Neurocardiogenic syncope occurs secondary to cerebral hypotension because of bradycardia, hypotension, or both. Head-up tilt-table test (HUTT) is the primary diagnostic test. Near-infrared spectroscopy (NIRS) is a noninvasive technology that directly monitors trends in regional tissue oxygen saturations over a specific body region. Placing an NIRS probe over the temporal region allows an indirect measurement of cerebral perfusion. Our hypothesis is that regional tissue oxygen saturation will decrease during an NCS episode and will remain stable in patients without syncope.
  
  
  METHODS
  The investigators conducted a retrospective review of all HUTT utilizing cephalic NIRS performed at our institution from August 2012 to January 2013. Tests were classified as positive, negative, or psychogenic reactions. Paired t-test was used to determine statistical significance of NIRS changes and one-way analysis of variance was used to analyze baseline characteristics among the three groups.
  
  
  RESULTS
  Twelve patients were included in the study (female = 10). The average age was 14.4 years (range: 12-17). Five tests were positive for NCS, four were negative, and three demonstrated psychogenic reactions. Patients with a positive test had a sudden, significant decrease in regional tissue oxygen saturations (P = .009) by an average of 11.3 ± 5.2% compared with baseline. The decrease in regional tissue oxygen saturation preceded symptoms, hypotension, and bradycardia in all patients. Regional tissue oxygen saturation levels remained stable in patients with a negative test or psychogenic syncope.
  
  
  CONCLUSIONS
  NIRS monitoring during HUTT produces a reliable, positive result that precedes clinical signs and symptoms. Further, it helps distinguish NCS from psychogenic syncope.
authors.affiliation: Section of Pediatric Cardiology, Department of Pediatrics, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Ind, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Ayers
authors.affiliation: Section of Pediatric Cardiology, Department of Pediatrics, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Ind, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Lawrence
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007196:Indiana; D008297:Male; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D056888:Patient Positioning; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D019265:Spectroscopy, Near-Infrared; D019462:Syncope, Vasovagal / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D018667:Tilt-Table Test; D013997:Time Factors
chemical_list: D015415:Biomarkers; D010100:Oxygen
keywords: Head-up Tilt-table Test; Near-infrared Spectroscopy; Syncope