Bacterial Meningitis

Findings:
CECT images show filling in of the subarachnoid space with abnormal enhancement. The sulci and cisterns are effaced. The midbrain appears compressed and has abnormal low attenuation. In addition, patchy low attenuation is present throughout the brain parenchyma. Sinus disease with air fluid levels is also noted.

Differential Diagnosis:
Bacterial meningitis, anoxic injury, diffuse subarachnoid hemorrhage, less likely metastatic disease or sarcoidosis.

Discussion:
The CT findings of bacterial meningitis are commonly nonspecific and even normal in the majority of cases. In severe cases, noncontrast evaluation may show abnormal ill defined filling of the subarachnoid spaces with isoattenuating material, which may show diffuse enhancement after contrast. The patient in this case was moribund at the time of the scan.
    -bacterial organisms -H. flu, Neisseria, S. pneumo comprise 80%.
    -by age group:
            -neonates: GBS, E coli
            -young children: Hflu
            -children>7: N. meningitides
            -adults: S. pneumo
   -dx usually clinically  (LP)

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