Meningitis & Brain Abscess

Terms in this set (16)

•Two common types:
-Tentorial: medial portion of the temporal lobe herniates into the tentorial notch and compresses the midbrain, peduncle, and third nerve
-Tonsillar: herniation of the cerebellar tonsils through the foramen magnum
•Etiology can include cerebral edema, space occupying lesions (abscesses, tumors, blood), hydrocephalus

Who is at risk for herniation?
•Previous studies proven that it is impossible to tell who will have increased ICP on CT
•Papilledema is not reliable
•Although CT findings are not always reliable, there are findings that suggest who is at risk for herniation

CT findings that suggest risk for herniation
• LP may cause herniation if brain shift exists with or without papilledema
•Perform CT before LP if clinical suspicion exists for brain shift and look for:
-Loss of differentiation of gray and white matter
-Effacement of CSF spaces, sulci, fissures, ventricles
-Displacement of brain structures

CT Findings that contraindicate LP
•Lateral shift of midline structures
•Loss of basilar cisterns
•Obliteration of the fourth ventricle
•Obliteration of superior cerebellar/quadrigeminal cisterns with sparing of the ambient cisterns

Treatment of Cerebral Herniation
•20% mannitol IV - 1g/kg over 15 minutes
-Effects last 4-6 hours.
•Corticosteroid: dexamethasone IV 12-24 mg IVP (Rosen states no benefit proven.)
•Intubate and hyperventilate

Who should undergo CT prior to LP: immunocompromised state, history of CNS disease, new onset seizure, papilledema, abnormal level of consciousness, focal neurologic deficit
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