Cerebral ischemia (CI) in bacterial meningitis (BM) has been associated with adverse outcome and may occur because of intracranial hypertension or reduced metabolic demand. It has also been speculated that increased cerebrovascular resistance (CVR) secondary to vasospasm or arterial occlusion may also lead to global CI; however measurement of CVR in clinical or experimental studies of BM has not been well documented. We have recently shown in a model of tumor necrosis factor (TNF)-induced meningitis (Tureen, J Clin Invest 1995, 95:1086) that intracisternal injection of TNF increases CVR and is associated with CI. The purpose of the present study was to determine whether increased CVR is present in experimental BM and whether it plays a role in CI. Using the model of Dacey and Sande, uninfected controls and rabbits with experimental BM due to Streptococcus pneumoniae had sequential measurement of cerebral perfusion pressure (CPP) = [mean blood pressure - intracranial pressure] and cerebral blood flow (CBF) at 0, 6 and 16 hours of infection. CVR was calculated by the following formula: CVR (mm Hg/ml/min/100gm) = CPP (mm Hg)/CBF (ml/min/100g). Results (Mean ± SD) are presented below. (N = # of animals). In addition to the increase in CVR in the infected group, there was a significant inverse correlation between CBF and CVR (r = -.796, P <.05 [Student's t-test]), suggesting that CI in meningitis may be mediated in part, by increased CVR.Table

Table 1
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