title: The middle cerebral artery flow velocities during head-up tilt testing in diabetic patients with autonomic nervous system dysfunction.
abstract: BACKGROUND
  The goal of this study was to examine the effects of diabetes mellitus on the trend of mean arterial velocity (v(m)) in both middle cerebral arteries during head-up tilt (HUT).
  
  
  METHODS
  The study was performed in 20 patients, 9 females and 11 males (mean age 51 +/- 12 years) with an average 17-year history of insulin-dependent diabetes mellitus type I or II and a dysfunction of the autonomic nervous system confirmed by cardiocirculatory tests [Valsalva maneuver, deep breathing test, handgrip test, orthostatic test and spectral analysis of heart rate (HR) variability], and 19 age-matched healthy volunteers, 9 females and 10 males (mean age 48 +/- 6.8 years). v(m) was measured by a transcranial Doppler monitoring system during a 5-min baseline period, followed by a 5-min HUT in the upright position (90 degrees ). Mean arterial blood pressure (MAP), HR and end-tidal CO(2) (Et-CO(2)) were monitored concomitantly.
  
  
  RESULTS
  In healthy volunteers, v(m) decreased stepwise during the first minute of HUT, reaching a minimum during the last 2 min of the test (v(m): basal 63.0 +/- 11.7 cm/s, 1st min 57.6 +/- 12.2 cm/s, 2nd min 55.9 +/- 12.6 cm/s, 3rd min 53.4 +/- 12.6 cm/s, 4th min 52.1 +/- 12.7 cm/s, 5th min 51.3 +/- 13.5 cm/s). In the supine position, v(m) recovered and reached the resting v(m) values. It declined gradually during HUT and less steeply in diabetic (v(m): basal 54.4 +/- 10.1 cm/s, 1st min 51.96 +/- 9.3 cm/s, 2nd min 50.7 +/- 11.6 cm/s, 3rd min 50.5 +/- 11.4 cm/s, 4th min 49.5 +/- 10.7 cm/s, 5th min 48.8 +/- 11.5 cm/s) than in healthy subjects. v(m) differed significantly (p = 0.00) between rest and HUT in both groups. The differences in MAP, HR and Et-CO(2) during rest and HUT between the groups were not statistically significant (p DeltaMAP = 0.36, p DeltaHR = 0.86, p DeltaEt-CO(2) = 0.97). The results of the analysis of variance of v(m) for repeated measurements between the two groups of subjects were highly significant (p = 0.00). The model of linear regression analysis was significant (p = 0.007). Diabetes was significant in the model (p = 0.00), while DeltaMAP, DeltaHR and DeltaEt-CO(2) were not.
  
  
  CONCLUSIONS
  These findings may indicate that vasomotor responses during HUT testing are decreased in diabetic patients.
authors.affiliation: University Medical Center Ljubljana, Department of Neurology, Laboratory of Neurosonology, Ljubljana, Slovenia. bojana.zvan@guest.arnes.si
authors.forename: Bojana
authors.initials: B
authors.lastname: Zvan
authors.forename: Marjan
authors.initials: M
authors.lastname: Zaletel
authors.forename: Janja
authors.initials: J
authors.lastname: Pretnar Oblak
authors.forename: Tomaz
authors.initials: T
authors.lastname: Pogacnik
authors.forename: Tomaz
authors.initials: T
authors.lastname: Kiauta
mesh_terms: D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018667:Tilt-Table Test; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D014666:Vasomotor System / Q000000981:diagnostic imaging / Q000503:physiopathology