Department of Neuroradiology and MRI, University Hospital of Grenoble, Grenoble, France.
Mov Disord. 2013 Apr;28(4):469-75. doi: 10.1002/mds.25267. Epub 2012 Dec 12.
The aim of this work was to study cerebral vasoreactivity to hypercapnia in Parkinson's disease (PD) before and after levodopa administration. The prospective study was conducted in 20 patients presenting with PD, using 3T blood oxygenation level-dependent (BOLD) functional MRI (fMRI) covering the whole brain. The hypercapnic stimulus was block-designed using carbogen inhalation, a gas mixture of 7% CO2 and 93% O2, before (OFF) and 60 minutes after administration of a suprathreshold (120%) therapeutic L-dopa dose (ON). Ten age-matched controls were enrolled for between-group comparisons. Analyses were conducted with a random effects model and corrected for multiple comparisons. No adverse reaction to the hypercapnic stimulus was reported. However, 10 patients and 2 controls were excluded because of incomplete protocol realization, inappropriate hypercapnic stimulus, or excessive movements, leaving 10 patients and 8 controls for further analyses. The hypercapnic stimulus increased whole-brain BOLD signal of 1.48% ± 0.06% (mean ± standard error) in controls, 1.59% ± 0.05% in patients OFF, and 1.62% ± 0.09% in patients ON. Regions of interest analyses showed a signal increase in gray matter of 2.60% ± 0.16% in controls, 2.89% ± 0.21% in patients OFF, and 2.87% ± 0.12% in patients ON. No global or regional significant difference was detected, when comparing patients OFF and ON L-dopa, or between patients and controls. Contrary to Alzheimer's disease, the vasoreactivity to hypercapnia was normal in PD before and after L-dopa administration, compared to controls. This negative result is an important finding, especially for neuroscientists using fMRI to investigate motricity and cognition, discarding a significant confounding effect.
本研究旨在探讨帕金森病（PD）患者左旋多巴治疗前后的脑血管对高碳酸血症的反应性。这项前瞻性研究纳入了 20 名 PD 患者，使用覆盖全脑的 3T 血氧水平依赖（BOLD）功能磁共振成像（fMRI）。采用高碳酸血症刺激的气室吸入法，以 7%二氧化碳和 93%氧气的混合气作为刺激气体，在未服用（OFF）和服用超阈值（120%）治疗剂量左旋多巴（ON）后 60 分钟进行。纳入 10 名年龄匹配的对照者进行组间比较。采用随机效应模型进行分析，并校正了多重比较。未报告对高碳酸血症刺激有不良反应。然而，由于方案执行不完整、高碳酸血症刺激不当或过度运动，有 10 名患者和 2 名对照者被排除在外，最终有 10 名患者和 8 名对照者纳入进一步分析。高碳酸血症刺激使对照组全脑 BOLD 信号增加 1.48%±0.06%（均值±标准误差），OFF 期患者增加 1.59%±0.05%，ON 期患者增加 1.62%±0.09%。感兴趣区分析显示，对照组灰质信号增加 2.60%±0.16%，OFF 期患者增加 2.89%±0.21%，ON 期患者增加 2.87%±0.12%。与 ON 期相比，OFF 期患者的 L-dopa 治疗前后或患者与对照者之间，均未检测到全脑或局部信号的显著差异。与阿尔茨海默病不同，与对照组相比，PD 患者在左旋多巴治疗前后对高碳酸血症的血管反应性正常。这一阴性结果是一个重要发现，特别是对于使用 fMRI 研究运动和认知的神经科学家而言，可以排除显著的混杂效应。
