Ventriculo-lumbar gradient of concentration of total cerebrospinal fluid proteins: 1 - mechanisms of origin

Abstract

In normal conditions there is a concentration gradient of proteins along the neuraxis. From a low level in the ventricles, ranging from 5 to 15 mg/10C ml, to an intermediate level in the cisterna magna, the protein content reaches its highest level in the lumbar sac, 12 to 44 mg/100 ml. Several mechanisms were considered to elucidate the origin of this gradient but many investigators think that the progressive increase of the protein concentration is best explained by the transfer of proteins from serum to the cerebrospinal fluid due to the relatively raised permeability of blood-cerebrospinal fluid barrier in the spinal subarachnoid space. This paper presents a study of the protein concentrations in cisternal and lumbar cerebrospinal fluid samples of patients with neurocysticercosis in activity. The 11 patients of the first group had free subarachnoid space communication between the cisterna magna and the lumbar sac; the 6 patients of the second group had a complete block of the subarachnoid space between these two levels. In every cerebrospinal fluid specimen the quantitative complement fixation test for cysticercus was performed and the titer determined in order to make an assessment of the central nervous system humoral immune response. The analysis of the data of this investigation shows that the concentration gradient of proteins is evident in the cerebrospinal fluid of patients with patency of the spinal subarachnoid space, and the ratio of concentrations of protein contents in simultaneous cisternal and lumbar samples was similar to that one observed in normal individuals. This gradient is also detected when the intensity of the humoral immune response is determined by quantitative complement fixation test for cysticercus in simultaneous cisternal and lumbar specimens. After the onset of spinal subarachnoid block, the confront of the results of the tests in cerebrospinal fluid samples, obtained before and after the blockage, shows a large increase both in the total protein content as well as the intensity of the humoral immune response, in the lumbar level. The similar increases both in protein concentration and titer of cysticercus complement fixation test in the lumbar fluid, in comparison with the cisternal fluid, in patients with patent spinal subarachnoid space, and the large simultaneous and similar increases in both protein content and titer of the cysticercus complement fixation test in the lumbar fluid of patients with spinal subarachnoid block are in disagreement with the usual explanation of the origin mechanisms of the gradient.(ABSTRACT TRUNCATED AT 400 WORDS)