Cerebral Oxygenation Monitoring for Detecting Critical Cerebral Hypoperfusion in Patients with Multiple System Atrophy during the Head-up Tilt Test

Objective Near infrared spectroscopy (NIRS) is a non-invasive optical technique to monitor cerebral tissue oxygen saturation (ScO2). The purpose of this study was to reveal the usefulness of ScO2 monitoring in evaluating cerebral circulation in patients with autonomic failure. Methods Nineteen patients with multiple system atrophy (MSA), who had autonomic failure, and 10 age-matched normal control subjects participated. In addition to blood pressure monitoring, ScO2 was recorded by a near-infrared spectroscopy instrument during head-up tilt (HUT) test. Results HUT tests induced postural symptoms in 9 MSA patients (presyncopal group), but not in 10 MSA patients (non-presyncopal group) or in any of the controls. ScO2, which decreased slightly in the controls and MSA patients, did not differ significantly between the MSA and control groups. With regard to MSA subgroups, the ScO2 reduction in the presyncopal group (-3.1±1.7%) was significantly larger than in the non-presyncopal group (-0.9±0.5%, P<0.005) and controls (-1.1±1.0%, P<0.05). The systolic blood pressure decreases during HUT in the non-presyncopal (-35.2±16.1 mmHg, P<0.01) and presyncopal (-54.3±27.5 mmHg, P<0.0005) groups were significantly greater than that in the control group (4.0±10.7 mmHg), but the difference between presyncopal and non-presyncopal groups was not significant. Conclusion In our study, ScO2 reduction seemed to be associated with presyncopal symptoms. ScO2 monitoring may be useful to detect cerebral hypoperfusion in MSA patients with autonomic failure.