[Significance of bromide levels in evaluation of the hemato-encephalic barrier during acute viral meningitis].

INTRODUCTION

Inflammatory diseases of the CNS are associated with increased permeability of blood-brain barrier due to vasculitis of cerebral blood vessels leading to regional ischaemia and necrosis. Many substances pass easily from the serum into the CSF through inflamed and damaged blood-brain barrier. Bromide partition test is one of the parameters for evaluation of the blood-brain barrier integrity during CNS inflammatory diseases. As early as 1929 Walter published a monograph on blood-brain barrier accentuating the value of bromide partition test for evaluation of the functional status of blood-brain barrier. In healthy individuals bromide partition test usually ranges from 2.9-3.5. In most patients with TB meningitis bromide partition test remains below 1.6 while it is usually higher in patients with serous meningitis of other aetiologies. However, the low bromide partition test may associate also some other viral and other serous meningitides accompanied with severe lesions of the blood-brain barrier, resulting in increased passage of sodium bromide from the serum into the CSF, so that the serum/CSF ratio is lower. The aim of th study was to calculate and analyze the results of bromide partition test in patients with acute viral meningitis and hyperproteinorachia above 0.70 g/l and to calculate and analyze the results of bromide partition test in patients with TB and parasitic meningitis. The results of bromide patirion tests were compared with results of other parameters for evaluation of the blood-brain barrier function.

METHOD

Titration method was used to determine the serum sodium bromide and CSF ratio. Sodium bromide oxidation into sodium bromate was the principle, where addition of potassium iodide is followed by release of equivalent amount of elementary iodide. Iodide is titrimetrically evidenced with thyosulphate, with starch as an indicator. In addition to bromide partition test functional condition of blood-brain barrier was also evaluated by albumin coefficients, albuminorachia and total proteinorachia.

RESULTS

In 6 of 30 patients (20%) with acute viral meningitis the bromide partition ratio was below 1.6, suggesting severe damage of blood-brain barrier in these patients: albumin coefficients exceeded 16.7 (mean = 24.7), albuminorachia was over 0.90 (mean = 1.38 g/l), and total proteinorachia over 3.0 g (mean = 3.1 g/l). The aetiology was confirmed in all patients: lymphocyte choriomeningitis virus in 5, COX B1 in one. Values of bromide partition test were higher on follow-up examination, and values of other parameters decreased, suggesting restitution of blood-brain barrier. The results are given in Table 1. Most severe damage of blood-brain barrier was evidenced in patients with lymphocyte choriomeningitis. Parameters for evaluation of functional condition of blood-brain barrier in patients with lymphocyte choriomeningitis and TB meningitis with most severe damage of the barrier, were compared. The results are given in Table 2. No differences between the compared parameters were found, i.e. no difference in the severity of blood-brain damage. Bromide patition test values were below 1.6 in all patients with TB meningitis and in 3 of 5 patients with parasitic meningitis.

DISCUSSION

Numerous studies have shown that bromide patition test value during TB meningitis was usually below 1.6. This is probably due to hypersensitivity reaction of the meninges to tuberculin which is located intrathecally and leads to blood-brain barrier damage. Use of antituberculous drugs does not affect the bromide partition test values in early stages of the disease. In all of our 15 patients with TB meningitis the bromide partition test values were below 1.6, coinciding with reference reports. However, we also measured bromide partition test values below 1.6 in 6 (20%) of 30 patients with acute viral meningitis with proteinorachia above 0,70 g/l (ABSTRACT TRUNCATED).