CEREBRAL BLOOD-FLOW VELOCITY AND PERFUSION IN PURULENT-MENINGITIS - ACOMPARATIVE TCD AND 99M-TC-HMPAO-SPECT STUDY

In 15 patients (median age 33 years; range 17-74 years) suffering from acute pneumococcal (10 cases) and meningococcal (five cases) meningit is, cerebral blood flow velocity (CBFV) was measured in the M-1 - segm ent of the middle cerebral artery (MCA) by transcranial Doppler sonogr aphy, and cerebral perfusion changes were evaluated by (99m)-Tc-hexame thylpropylene amine oxime single photon emission computed tomography ( HMPAO SPECT). The objective of the study was to test whether increased CBFV during the acute phase of purulent meningitis reflects hyperemia , and to evaluate focal perfusion abnormalities and their correlation to CBFV changes. In eight patients with marked side-differences in CBF Vs during the acute phase of the disease SPECT scans were normal in fi ve. In three patients unilateral perfusion defects correlated with the side of higher CBFV. In seven patients presenting with symmetrically elevated CBFV, SPECT scans were normal in four and revealed focal abno rmalities in the remaining three. Follow up SPECT scans were normal in 14/15 patients. The results of our study suggest that elevated CBFV i n acute bacterial meningitis does not reflect cerebral hyperemia. Foca l cerebral perfusion defects occur independently from functional alter ations in the cerebral microvasculature. A causative pathophysiologic relationship of high CBFV and focal perfusion defects cannot be drawn from these data.