Impaired cerebral autoregulation in patients with shy-drager syndrome

Abstract It is still debated whether cerebral autoregulation is preserved in patients presenting Shy-Drager syndrome (SD). In order to evaluate cerebral autoregulation in this disease the authors studied 5 patients with SD and 5 healthy control subjects by means of transcranial Doppler. Changes in mean flow velocity (MV) in the middle cerebral artery (MCA), as well as changes of the systemic mean arterial blood pressure (MBP) were measured at the same time during a tilt-table test. When the patients were tilted from the rest to the orthostatic position, MCA MV showed a rapid and significant decrease in all SD patients (−52.8%); the MCA MV values remained low during 10 minutes at 90°; control patients did not show similar changes (−6.9%), (P=0.0003). Although MBP values showed a considerable decrease during the test in SD patients (−31.0%), these changes never went below the cerebral autoregulation threshold. The authors’ data are suggestive of an impairment of cerebral autoregulation in SD patients.