Abstract
.Significance: Cerebral oxygenation changes in the superior, middle, and medial gyri were used to elucidate spatial impairments of autonomic hemodynamic recovery during the head-up tilt table test (HUTT) in Parkinson’s disease (PD) patients with orthostatic intolerance (OI) symptoms.Aim: To analyze dynamic oxygenation changes during the HUTT and classify PD patients with OI symptoms using clinical and oxygenation features.Approach: Thirty-nine PD patients with OI symptoms [10: orthostatic hypotension (PD-OH); 29: normal HUTT results (PD-NOR)] and seven healthy controls (HCs) were recruited. Prefrontal oxyhemoglobin (HbO) changes during the HUTT were reconstructed with diffuse optical tomography and segmented using the automated anatomical labeling system. Decision trees were used for classification.Results: HCs and PD-NOR patients with positive rates of HbO change (PD-POS) showed the greatest HbO recovery in the superior frontal gyrus (SFG) during tilt. PD-OH and PD-NOR patients with negative rates of HbO change (PD-NEG) showed asymmetric reoxygenation. The classification accuracy was 89.4% for PD-POS versus PD-NEG, 71% for PD-NOR versus PD-OH, and 55.8% for PD-POS versus PD-NEG versus PD-OH. The oxygenation features were more discriminative than the clinical features.Conclusions: PD-OH showed decreased right SFG function, which may be associated with impaired compensatory autonomic responses to orthostatic stress.
Highlights
The head-up tilt test (HUTT) with simultaneous blood pressure (BP) monitoring has been widely used to diagnose orthostatic hypotension (OH) and it comprises three phases: dynamic tilt, static tilt, and post-tilt.[1,2,3,4,5] OH is one NeurophotonicsDownloaded From: https://www.spiedigitallibrary.org/journals/Neurophotonics on 13 Jan 2022 Terms of Use: https://www.spiedigitallibrary.org/terms-of-useOct–Dec 2020 Vol 7(4)Phillips et al.: Regional analysis of cerebral hemodynamic changes during the head-up tilt test. . .etiology of orthostatic intolerance (OI) diagnosed based on a reduction in BP within 3 min of the static tilt phase
In our recent diffuse optical tomography (DOT) study, we found that the rate of oxyhemoglobin (HbO) changes from the dynamic to the static tilt phase may be a sensitive marker for differentiating healthy controls (HCs) from Parkinson’s disease (PD) patients with OH (PD-OH).[18]
Few studies have investigated the central regions that are associated with PD with OH (PD-OH);[21,22] we extended our previous DOT study to include a regional analysis of cerebral oxygenation across the frontal area during the dynamic and static tilt phases of HUTT in PD patients showing OI symptoms.[18]
Summary
The head-up tilt test (HUTT) with simultaneous blood pressure (BP) monitoring has been widely used to diagnose orthostatic hypotension (OH) and it comprises three phases: dynamic tilt (supine to 70° tilt), static tilt (remain tilted at 70°), and post-tilt (return to supine).[1,2,3,4,5] OH is one NeurophotonicsDownloaded From: https://www.spiedigitallibrary.org/journals/Neurophotonics on 13 Jan 2022 Terms of Use: https://www.spiedigitallibrary.org/terms-of-useOct–Dec 2020 Vol 7(4)Phillips et al.: Regional analysis of cerebral hemodynamic changes during the head-up tilt test. . .etiology of orthostatic intolerance (OI) diagnosed based on a reduction in BP within 3 min of the static tilt phase. The HUTT has poor reproducibility and low sensitivity.[6,7] Given that OH is common among patients with Parkinson’s disease (PD), early and accurate diagnosis is crucial for providing optimal intensive care to them.[8,9,10,11] Several studies have explored alternative biomarkers to diagnose OH and overcome the limitations of HUTT.[12,13,14] Optical methods, such as near-infrared spectroscopy (NIRS) and diffuse optical tomography (DOT), have demonstrated accuracy and convenience for real-time monitoring of cerebral oxygenation, during postural changes.[15,16,17] In our recent DOT study, we found that the rate of oxyhemoglobin (HbO) changes from the dynamic to the static tilt phase may be a sensitive marker for differentiating healthy controls (HCs) from PD patients with OH (PD-OH).[18] Our previous study suggested that DOT measurements provide information on cerebral reoxygenation that cannot be gleaned from conventional BP monitoring during HUTT, in patients with PD who have normal HUTT results (PD-NOR).[18]
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