Open AccessOsmotic pressure of serum and cerebrospinal fluid in patients with suspected neurological conditions
Author(s) -
Tetsuya Akaishi,
Toshiyuki Takahashi,
Ichiro Nakashima,
Michiaki Abe,
Masashi Akiyama,
Tadashi Ishii
Publication year - 2020
Publication title -
neural regeneration research/neural regeneration research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.93
H-Index - 38
eISSN - 1876-7958
pISSN - 1673-5374
DOI - 10.4103/1673-5374.268906
Subject(s) - osmole , osmotic concentration , cerebrospinal fluid , parenchyma , hydrostatic pressure , medicine , osmotic pressure , tonicity , endocrinology , chemistry , pathology , biochemistry , mechanics , physics
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. This study was approved by the Institutional Review Board of the Tohoku University Hospital (approval No. IRB No. 2015-1-257) on July 29, 2015.