Magnesium and inorganic phosphate content in CSF related to blood-brain barrier function in neurological disease.

In normal controls and in a large number of neurological patients divided into certain disease groups both Mg and PO4 were determined in cerebrospinal fluid (CSF) and serum. For both Mg and PO4 there was a marked concentration gradient between CSF and serum in normals where Mg was higher and PO4 content lower in CSF. Comparison of CSF values with serum values of patients showed pathological changes only in CSF, serum values always being within the control range. A number of disease processes associated with a disturbance of blood-brain barrier (BBB) function such as inflammatory CNS disease or CNS tumors showed significant alterations of PO4 concentrations in CSF which are interpreted as an approximation of serum values. A similar decrease of Mg did not reach statistical significance. Both Mg and PO4 in CSF showed a correlation with CSF protein concentrations, but no relationship with cells in CSF. Patients with cerebrosvascular disease were not significantly different from controls as regards their Mg and PO4 in CSF, but a small subgroup consisting of patients with an intracranial hemorrhage showed elevation of both Mg and PO4 which could signify cell necrosis rather than BBB dysfunction. Patients with disc protrusion or peripheral neuropathy did not demonstrate any abnormality of CSF Mg and PO4. In the multiple sclerosis group individual patients had elevated CSF concentrations of PO4 but the group as a whole is not different from the controls.