Is the blood-CSF barrier altered in disease?

OBJECTIVE: To illustrate the influence of cerebrospinal fluid (CSF) flow on lumbar CSF protein concentration and to test for an altered blood-CSF barrier permeability as additional influence. PATIENTS AND METHODS: Consecutively hospitalized patients with normotensive hydrocephalus (n = 21) underwent lumbar puncture with CSF being sampled in sequential portions. CSF/blood quotients of albumin (QAlb) and of immunoglobulin G (QIgG) were compared intra-individually and with calculated values from a reference patient sample. RESULTS AND
CONCLUSIONS: QAlb and QIgG of intra-individual sequential portions correlated highly with each other (median r = 0.95), suggesting lumbar CSF flow as the main thecal determinant of lumbar QAlb and QIgG variation. In addition, QIgG, relative to QAlb, was significantly lower in study patients compared with a reference patient sample (P = 0.002), implying an alteration of the blood-CSF barrier permeability as a minor determinant of QAlb and QIgG variation in study patients.