Clinical implication of protein gradients in the lumbar cerebrospinal fluid

Background: Concentration gradients for proteins between ventricular (low level), cisternal (intermediate level) and lumbar (high level) cerebrospinal fluid (CSF) have been demonstrated (1). However, although a gradient for total protein along the CSF system has been well established, the gradient for total protein along the lumbar sac has not been well studied. Objective: The objective of this study was to determine whether the gradient for total protein in the lumbar CSF exists. Patients and Methods: We studied 18 patients (age, sex) with communicating hydrocephalus (8 patients with normal pressure hydrocephalus, and 10 patients with atrophic hydrocephalus). Exactly 20 ml of lumbar CSF were collected during a lumbar puncture and the first, the fifth, the tenth, the fifteenth, and the twentieth ml of the lumbar CSF were separated into test tubes for total protein measurement using colorimetric (pyrogallol red) method. Concentrations of total protein were expressed in mg/l. The Student-t test for paired data was used for statistical evaluation. Results: Our results showed statistically significant different concentrations of total protein between the first (647, 66p 84, 56) and the twentieth ml (298, 69p 40.82) of lumbar CSF. Conclusions: These results indicate that lumbar CSF is not a homogeneous fluid and that during a lumbar puncture standardized volume of the lumbar CSF should be obtained for protein analysis.