Levodopa does not change cerebral vasoreactivity in Parkinson's disease

Authors

  • Alexandre Krainik MD, PhD,

    Corresponding author
    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
    • Department of Neuroradiology and MRI, University Hospital of Grenoble, Grenoble, France
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  • Audrey Maillet PhD,

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
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  • Vanessa Fleury MD,

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
    3. Department of Neurology, University Hospital of Grenoble, Grenoble, France
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  • Mehmet Sahin MD,

    1. Department of Neuroradiology and MRI, University Hospital of Grenoble, Grenoble, France
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  • Irène Troprès PhD,

    1. Joseph Fourier University, SFR1, Grenoble, France
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  • Laurent Lamalle PhD,

    1. Joseph Fourier University, SFR1, Grenoble, France
    2. INSERM, Grenoble, France
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  • Stephane Thobois MD, PhD,

    1. Hospices Civils de Lyon, Hôpital Neurologique, Université Lyon I, Faculté de Médecine Lyon Sud, CNRS, UMR 5229, Lyon, France
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  • Valerie Fraix MD, PhD,

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
    3. Department of Neurology, University Hospital of Grenoble, Grenoble, France
    4. Department of Neurology, University Hospitals of Geneva, Geneva, Switzerland
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  • Marjorie Villien PhD,

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
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  • Jan Warnking PhD,

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
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  • Pierre Pollak MD, PhD,

    1. Department of Neurology, University Hospitals of Geneva, Geneva, Switzerland
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  • Serge Pinto PhD,

    1. Laboratoire Parole et Langage, UMR 7309 CNRS/Aix-Marseille University, Aix-en-Provence, France
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  • Paul Krack MD, PhD

    1. Inserm U836, Grenoble, France
    2. Joseph Fourier University, Grenoble Institute of Neurosciences UMR-S836, Grenoble, France
    3. Department of Neurology, University Hospital of Grenoble, Grenoble, France
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  • Funding agencies: This project was supported by the University Hospital of Grenoble and the France Parkinson Association.

  • Relevant conflicts of interest/financial disclosures: Nothing to report.

  • Full financial disclosures and author roles may be found in the online version of this article.

Correspondence to: Prof. Alexandre Krainik, MRI Unit, BP 217, CHU Grenoble, F-38043 Grenoble, France; akrainik@chu-grenoble.fr

Abstract

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. © 2012 Movement Disorder Society

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