title: Regional differences in the cerebral blood flow velocity response to hypobaric hypoxia at high altitudes.
abstract: Symptoms of acute mountain sickness (AMS) may appear above 2,500 m altitude, if the time allowed for acclimatization is insufficient. As the mechanisms underlying brain adaptation to the hypobaric hypoxic environment are not fully understood, a prospective study was performed investigating neurophysiological changes by means of near infrared spectroscopy, electroencephalograpy (EEG), and transcranial doppler sonography at 100, 3,440 and 5,050 m above sea level in the Khumbu Himal, Nepal. Fourteen of the 26 mountaineers reaching 5,050 m altitude developed symptoms of AMS between 3,440 and 5,050 m altitude (Lake-Louise Score ⩾3). Their EEG frontal beta activity and occipital alpha activity increased between 100 and 3,440 m altitude, i.e., before symptoms appeared. Cerebral blood flow velocity (CBFV) in the anterior and middle cerebral arteries (MCAs) increased in all mountaineers between 100 and 3,440 m altitude. During further ascent to 5,050 altitude, mountaineers with AMS developed a further increase in CBFV in the MCA, whereas in all mountaineers CBFV decreased continuously with increasing altitude in the posterior cerebral arteries. These results indicate that hypobaric hypoxia causes different regional changes in CBFV despite similar electrophysiological changes.
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.|Department of Palliative Medicine, Specialized Palliative Home Care Team, University of Munich, Munich, Germany.
authors.forename: Berend
authors.initials: B
authors.lastname: Feddersen
authors.affiliation: Department of Internal Medicine, Sinai Hospital, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Pritam
authors.initials: P
authors.lastname: Neupane
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Thanbichler
authors.affiliation: Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Hadolt
authors.affiliation: Klinik für Neurochirurgie, Dr Horst Schmidt Klinik, Wiesbaden, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Sattelmeyer
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfefferkorn
authors.affiliation: Department of Neuropsychology, Landeskrankenhaus Rankweil, Rankweil, Austria.
authors.forename: Robb
authors.initials: R
authors.lastname: Waanders
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.
authors.forename: Soheyl
authors.initials: S
authors.lastname: Noachtar
authors.affiliation: Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.|Department of Neurology, Franz-Tappeiner Krankenhaus, Meran, Italy.
authors.forename: Harald
authors.initials: H
authors.lastname: Ausserer
mesh_terms: D000064:Acclimatization; D000328:Adult; D000368:Aged; D000513:Alpha Rhythm; D000532:Altitude Sickness / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001611:Beta Rhythm; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000378:metabolism; D002536:Cerebral Arteries / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D004569:Electroencephalography; D005260:Female; D006801:Humans; D002534:Hypoxia, Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009051:Mountaineering; D009778:Occipital Lobe / Q000098:blood supply; D010101:Oxygen Consumption; D011446:Prospective Studies; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide