title: Multiparametric Magnetic Resonance Investigation of Brain Adaptations to 6 Days at 4350 m.
abstract: OBJECTIVE
  Hypoxic exposure in healthy subjects can induce acute mountain sickness including headache, lethargy, cerebral dysfunction, and substantial cerebral structural alterations which, in worst case, can lead to potentially fatal high altitude cerebral edema. Within this context, the relationships between high altitude-induced cerebral edema, changes in cerebral perfusion, increased brain parenchyma volume, increased intracranial pressure, and symptoms remain unclear.
  
  
  METHODS
  In 11 subjects before and after 6 days at 4350 m, we performed multiparametric magnetic resonance investigations including anatomical, apparent diffusion coefficient and arterial spin labeling sequences.
  
  
  RESULTS
  After the altitude stay, while subjects were asymptomatic, white matter volume (+0.7 ± 0.4%, p = 0.005), diffusion (+1.7 ± 1.4%, p = 0.002), and cerebral blood flow (+28 ± 38%; p = 0.036) were significantly increased while cerebrospinal fluid volume was reduced (-1.4 ± 1.1%, p = 0.009). Optic nerve sheath diameter (used as an index of increased intracranial pressure) was unchanged from before (5.84 ± 0.53 mm) to after (5.92 ± 0.60 mm, p = 0.390) altitude exposure. Correlations were observed between increases in white matter volume and diffusion (rho = 0.81, p = 0.016) and between changes in CSF volume and changes in ONSD s (rho = -0.92, p = 0.006) and symptoms during the altitude stay (rho = -0.67, p = 0.031).
  
  
  CONCLUSIONS
  These data demonstrate white matter alterations after several days at high altitude when subjects are asymptomatic that may represent the normal brain response to prolonged high altitude exposure.
authors.affiliation: HP2 Laboratory, Université Grenoble AlpesGrenoble, France; U1042, Institut National de la Santé et de la Recherche MédicaleGrenoble, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Verges
authors.affiliation: HP2 Laboratory, Université Grenoble AlpesGrenoble, France; U1042, Institut National de la Santé et de la Recherche MédicaleGrenoble, France; Inter-Universitary Laboratory of Human Movement Biology, Université Savoie Mont BlancChambéry, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rupp
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Villien
authors.affiliation: U836, Institut National de la Santé et de la Recherche Médicale Grenoble, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamalle
authors.affiliation: U836, Institut National de la Santé et de la Recherche Médicale Grenoble, France.
authors.forename: Irène
authors.initials: I
authors.lastname: Troprés
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Poquet
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Warnking
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: François
authors.initials: F
authors.lastname: Estève
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bouzat
authors.affiliation: Grenoble Institute of Neurosciences, Université Grenoble AlpesGrenoble, France; SFR1, Université Grenoble AlpesGrenoble, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Krainik
keywords: altitude; brain volume; cerebral blood flow; diffusion; hypoxia; intracranial pressure