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.