E. Titianova 1,2, I. Velcheva 3, S. Karakaneva 1
1 Clinic of Functional Diagnostics of Nervous System, Military Medical Academy – Sofia,
2 Medical Faculty of Sofia University St. Kl. Ohridski – Sofia,
3 State University Hospital of Neurology and Psychiatry, Medical University – Sofia, Bulgaria

Objective: To study the orthostatic adjustment of cerebral hemodynamics in orthostatic intolerance (OI), based on classification of Thulesius (1976).

Material and Methods: Hemodymanic changes associated with orthostatic challenge were studied in 20 volunteers and 30 patients with OI using a specially designed protocol (E. Titianova and J. Nader, 1999) – a passive 70-degree tilt of the upper part of the body followed by a passive 90-degree whole body tilting and an active stand-up (each one lasting 10 minutes and followed by return to the lying position) were applied. Mean blood pressure (MBP), heart rate and mean blood flow velocity (BFV) of both middle cerebral arteries (MCA) were determined after 10 minutes of rest and after 1, 5 and 10 minutes of each orthostatic position.