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How does head position induced intracranial pressure changes impact sympathetic activity and cerebral blood flow?

  • Marc Kermorgant
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
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  • Marc Labrunée
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France

    Department of Rehabilitation, University Hospital of Toulouse, Toulouse, France
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  • Fabien Despas
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
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  • Ophélie Hélissen
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
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  • Thomas Geeraerts
    Affiliations
    Department of Anesthesiology and Intensive Care, University Hospital of Toulouse, Toulouse, France

    Toulouse NeuroImaging Center – ToNIC, UMR 1214, Inserm/Université Toulouse III - Paul Sabatier, Toulouse, France
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  • Elisabeth Lambert
    Affiliations
    School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia
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  • Eric Schmidt
    Affiliations
    Department of Neurosurgery and Institute for Neurosciences, University Hospital of Toulouse, Toulouse, France
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  • Jean-Michel Senard
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France

    Department of Clinical Pharmacology, University Hospital of Toulouse, Toulouse, France
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  • Dina N. Arvanitis
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
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  • Author Footnotes
    1 These authors have equal contribution.
    Nathalie Nasr
    Correspondence
    Corresponding author at: Institute of Cardiovascular and Metabolic Diseases (I2MC), U1297 INSERM, 1 avenue du Professeur Jean Poulhès, 31432 Toulouse Cedex, France; Department of Neurology, University Hospital of Toulouse, Toulouse, France.
    Footnotes
    1 These authors have equal contribution.
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France

    Department of Neurology, University Hospital of Toulouse, Toulouse, France
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  • Author Footnotes
    1 These authors have equal contribution.
    Anne Pavy-Le Traon
    Footnotes
    1 These authors have equal contribution.
    Affiliations
    UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France

    Department of Neurology, University Hospital of Toulouse, Toulouse, France

    MEDES, Institute for Space Physiology and Medicine, Toulouse, France
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  • Author Footnotes
    1 These authors have equal contribution.
Published:September 23, 2022DOI:https://doi.org/10.1016/j.autneu.2022.103036

      Abstract

      Purpose

      Acute head-down-tilt (HDT) simulates short duration hemodynamic impact of microgravity. We sought to determine whether an increase in ICP caused by acute HDT affects sympathetic nervous system activity and cerebral blood flow velocities (CBFV) in healthy male volunteers.

      Methods

      HDT protocol was established as follows: basal condition immediately followed by gradual negative angles (−10°, −20° and −30°) lasting 10mn and then a return to basal condition. Velocities in the MCA (CBFV) were monitored using TCD. Sympathetic activity was assessed using MSNA. Baroreflex sensitivity (BRS) was measured using the sequence method. ICP changes were assessed using ultrasonography of the optic nerve sheath diameter (ONSD). Cerebral autoregulation (CA) was evaluated by transfer function and the autoregulatory index (Mxa).

      Results

      Twelve male volunteers (age: 35 ± 2 years) were included. Neither blood pressure nor heart rate was significantly modified during HDT. ONSD increased significantly at each step of HDT and remained elevated during Recovery. MSNA burst incidence increased at −30°. A positive correlation between variations in ONSD and variations in MSNA burst incidence was observed at −20°. CBFV were significantly diminished at −20° and −30. In the LF band, the transfer function coherence was reduced at −30° and the transfer function phase was increased at −30° and during Recovery.

      Discussion

      We found that an acute though modest increase in ICP induced by HDT was associated with an increase of sympathetic activity as assessed by MSNA, and with a reduction of CBFV with preserved CA.

      Keywords

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