Osmotic pressure of serum and cerebrospinal fluid in patients with suspected neurological conditions

Tetsuya Akaishi, Toshiyuki Takahashi, Ichiro Nakashima, Michiaki Abe, Masashi Aoki, Tadashi Ishii

Research output: Contribution to journalArticle

Abstract

Interstitial fluid movement in the brain parenchyma has been suggested to contribute to sustaining the metabolism in brain parenchyma and maintaining the function of neurons and glial cells. The pulsatile hydrostatic pressure gradient may be one of the driving forces of this bulk flow. However, osmotic pressure-related factors have not been studied until now. In this prospective observational study, to elucidate the relationship between osmolality (mOsm/kg) in the serum and that in the cerebrospinal fluid (CSF), we simultaneously measured the serum and CSF osmolality of 179 subjects with suspected neurological conditions. Serum osmolality was 283.6 ± 6.5 mOsm/kg and CSF osmolality was 289.5 ± 6.6 mOsm/kg. Because the specific gravity of serum and CSF is known to be 1.024-1.028 and 1.004-1.007, respectively, the estimated average of osmolarity (mOsm/L) in the serum and CSF covered exactly the same range (i.e., 290.5-291.5 mOsm/L). There was strong correlation between CSF osmolality and serum osmolality, but the difference in osmolality between serum and CSF was not correlated with serum osmolality, serum electrolyte levels, protein levels, or quotient of albumin. In conclusion, CSF osmolarity was suggested to be equal to serum osmolarity. Osmolarity is not one of the driving forces of this bulk flow. Other factors such as hydrostatic pressure gradient should be used to explain the mechanism of bulk flow in the brain parenchyma.

Original languageEnglish
Pages (from-to)944-947
Number of pages4
JournalNeural Regeneration Research
Volume15
Issue number5
DOIs
Publication statusPublished - 2020 May 1

Keywords

  • brain parenchyma
  • bulk flow
  • cerebrospinal fluid
  • hydrostatic pressure
  • interstitial fluid
  • osmolarity
  • osmotic pressure

ASJC Scopus subject areas

  • Developmental Neuroscience

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