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Continuous Video Electroencephalogram during Hypoxia-Ischemia in Neonatal Mice
Published on: June 11, 2020
Early brain swelling in acute hypoxia
David J Dubowitz1, Edward A W Dyer, Rebecca J Theilmann
1UCSD Centre for Functional MRI, 9500 Gilman Dr., MC 0677, La Jolla, CA 92093-0677, USA. dubowitz@ucsd.edu
Summary
Brain swelling occurs rapidly during acute hypoxia, with cerebrospinal fluid shifts happening within 40 minutes. This early brain swelling response to hypoxia is consistent across all individuals, regardless of acute mountain sickness susceptibility.
Area of Science:
- Neuroscience
- Altitude Medicine
- Physiology
Background:
- Acute mountain sickness (AMS) and high-altitude cerebral edema share clinical similarities, suggesting cerebral swelling is key to AMS pathophysiology.
- High-altitude hypoxia and hypocapnia impact cerebral circulation, but their interaction and effects on AMS susceptibility remain unclear.
Purpose of the Study:
- To investigate if individuals susceptible to AMS exhibit different brain swelling responses to acute hypoxia compared to resistant individuals.
- To quantify changes in cerebral blood flow, cerebral blood volume, and cerebrospinal fluid volume during acute hypoxia.
Main Methods:
- Utilized quantitative arterial spin-labeling and volumetric MRI to measure physiological changes.
- Assessed cerebral blood flow and cerebrospinal fluid (CSF) volume changes over 40 minutes of acute hypoxia.
- Compared AMS-susceptible (n=6) and AMS-resistant (n=6) groups with high-altitude experience.
Main Results:
- Significant decrease in intracranial CSF volume (-10.5 ml) within 40 minutes of hypoxia (P < 0.001).
- Significant increases observed in cerebral blood volume (CBV) (+2.3 ml, P < 0.005) and brain parenchyma volume (+8.2 ml, P < 0.001).
- No significant differences in these acute changes were found between AMS-susceptible and AMS-resistant groups.
Conclusions:
- Brain swelling occurs early in acute hypoxia, evidenced by rapid CSF shifts within 40 minutes.
- These acute physiological changes in brain volume are present in all individuals, irrespective of their susceptibility to AMS.
- The study provides new insights into the initial cerebral responses to hypoxia, challenging previous timelines for brain swelling onset.
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