Blood-arachnoid barrier disruption in experimental rat meningitis detected using gadolinium-enhancement ratio imaging.

Disruption of the central nervous system (CNS) barriers is one of the major pathophysiological consequences of bacterial meningitis. The increase in the permeability of the CNS barriers caused by the disruption is thought to contribute to the development of adverse neurological outcomes. We have established a method by which the CNS barrier permeability can be demonstrated by the gadolinium-enhancement ratio (GER) calculated from the T₁ weighted image (T₁WI) which is based on gadolinium-enhanced magnetic resonance imaging (GdEMRI). The present study examined the disruption of CNS barriers such as blood-brain barrier (BBB), blood-cerebrospinal fluid barrier (BCSFB) and blood-arachnoid barrier (BAB) in rats with meningitis induced by lipopolysaccharide (LPS)- or interleukin (IL)-1β. Four hours after intracisternal injection of LPS or IL-1β, severe disruption of the BAB, but not the BBB or BCSFB, was observed. This suggests that the BAB, rather than the BBB or BCSFB, plays a key role in the influx of blood-borne cells and substances during meningitis. The BAB is therefore more vulnerable to disruption than the BBB or BCSFB during meningitis in rats. In addition, GdEMRI with GER imaging analysis appears to be useful in spatio-temporal studies on the function of the CNS barriers under various physiological and pathological conditions.