title: Cerebral hemodynamics in orthostatic intolerance with normal head-up tilt test.
abstract: OBJECTIVE
  Orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS) are well-known causes of orthostatic intolerance (OI). In addition, there are OI patients who are characterized by the symptoms of OI and lack of abnormal findings in head-up tilt (HUT) test. The aim of this study was to determine the cerebral hemodynamic changes in HUT test of OI patients with normal HUT (OINH).
  
  
  METHODS
  Two hundred and sixty-one OI patients and 50 healthy controls were enrolled in this study. All subjects underwent transcranial Doppler test while performing the HUT test. Forty-five patients had OH, 33 patients had POTS, and 183 patients had OINH. Blood pressures, heart rate, cerebral blood flow velocities (CBFVs), end-tidal carbon dioxide (ET-PCO2 ), cerebral critical closing pressure (CCP), cerebral perfusion pressure (CPP), and cerebral vascular resistance (CVR) were measured during HUT test. We compared the hemodynamic parameters of OINH with those of OH, POTS, and healthy controls.
  
  
  RESULTS
  Reduced CBFVs, CPP, and ET-PCO2 and elevated CCP were observed in the HUT test of all four groups. CVR was reduced in three OI patients. The drops in systolic CBFV, CPP, and CVR of OINH patients were greater than those of healthy controls. The changes in parameters in the HUT test of OINH group were not different from those of OH and POTS groups except prominent decrements of CPP and CVR in OH group.
  
  
  CONCLUSIONS
  Our findings suggest that OINH is true OI sharing the common pathomechanism of OH and POTS.
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: K J
authors.initials: KJ
authors.lastname: Shin
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: S E
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: K M
authors.initials: KM
authors.lastname: Park
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: J
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: S Y
authors.initials: SY
authors.lastname: Ha
authors.affiliation: Department of Neurology, Haeundae Paik Hospital, Inje University, Busan, South Korea.
authors.forename: S E
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Department of Neurology, School of Medicine, Gyeongsang National University, Jinju, South Korea.
authors.forename: O-Y
authors.initials: OY
authors.lastname: Kwon
mesh_terms: D000328:Adult; D001794:Blood Pressure; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D054971:Orthostatic Intolerance / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D018667:Tilt-Table Test
keywords: hemodynamic; orthostatic hypotension; orthostatic intolerance; postural orthostatic tachycardia syndrome; transcranial Doppler