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Cerebral blood flow velocity and perfusion in purulent meningitis: a comparative TCD and 99M-TC-HMPAO-SPECT study
1Department of Neurology, Neuro Intensive Care Unit, University of Innsbruck, Innsbruck, Austria.
Abstract:
In 15 patients (median age 33 years; range 17-74 years) suffering from acute pneumococcal (10 cases) and meningococcal (five cases) meningitis, cerebral blood flow velocity (CBFV) was measured in the M1 - segment of the middle cerebral artery (MCA) by transcranial Doppler sonography, and cerebral perfusion changes were evaluated by 99m-Tc-hexamethylpropylene 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 CBFVs during the acute phase of the disease SPECT scans were normal in five. 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 abnormalities in the remaining three. Follow up SPECT scans were normal in 14/15 patients. The results of our study suggest that elevated CBFV in acute bacterial meningitis does not reflect cerebral hyperemia. Focal cerebral perfusion defects occur independently from functional alterations in the cerebral macrovasculature. A causative pathophysiologic relationship of high CBFV and focal perfusion defects cannot be drawn from these data.
Insights
Elevated cerebral blood flow velocity in bacterial meningitis does not indicate hyperemia. Focal brain perfusion defects in meningitis appear unrelated to macrovascular changes, suggesting independent pathophysiological processes.
Area of Science:
- Neurology
- Infectious Diseases
- Medical Imaging
Background:
- Bacterial meningitis can cause significant neurological complications.
- Cerebral blood flow velocity (CBFV) and perfusion are critical indicators of brain health.
Purpose of the Study:
- To determine if increased CBFV in acute bacterial meningitis signifies hyperemia.
- To assess focal perfusion abnormalities and their relationship with CBFV changes.
Main Methods:
- Transcranial Doppler sonography measured CBFV in the middle cerebral artery (MCA).
- 99m-Tc-hexamethylpropylene amine oxime single photon emission computed tomography (HMPAO SPECT) evaluated cerebral perfusion.
- 15 patients with acute pneumococcal or meningococcal meningitis were studied.
Main Results:
- Elevated CBFV did not consistently correlate with cerebral hyperemia.
- Focal perfusion defects were observed in some patients, independent of macrovascular changes.
- Follow-up SPECT scans showed normal perfusion in most patients.
Conclusions:
- Increased CBFV in acute bacterial meningitis is not indicative of hyperemia.
- Focal cerebral perfusion defects in meningitis occur separately from macrovascular alterations.
- No direct causal link between high CBFV and focal perfusion defects was established.