The blood-brain barrier (BBB) function in childhood central nervous system (
CNS) infections was evaluated, using cerebrospinal fluid (CSF) and paired serum samples from 30 controls and 74 patients aged from 1 to 15 years with various
CNS infections. The 74 patients included 34 cases of
aseptic meningitis, 24 of
encephalitis and 16 of purulent
meningitis. The degree of BBB damage was graded by CSF/
serum albumin ratio, and
IgG production by
IgG index (
IgG ratio/
albumin ratio of CSF to serum). In the acute stage, patients with purulent
meningitis had greater elevation of the
albumin ratio than other study groups. The patients with
encephalitis, especially chronic
encephalitis, had a selectively elevated
IgG index compared to other groups. Most patients with
aseptic meningitis showed little or no elevation of
albumin ratio and
IgG index. This study demonstrated the nature of various degrees of BBB damage and intra-BBB
IgG production in different infectious
CNS diseases in children. BBB damage is most severe in cases of purulent
meningitis, while the intrathecal
IgG production is greatest in chronic
encephalitis. These abnormalities disappear as the inflammatory processes subside.