Meningitis: inflammation of the meninges.
Encephalitis: inflammation of part of the brain (any part).
Presentation: Fever, neck stiffness, and mental status changes. 50% have all three. When adding headache, patients with meningitis have 95% chance of presenting with >2 of the 5.
Start antibiotics as soon as you’re thinking of bacterial meningitis.
Start empiric steroids. If youre thinking bacterial meningitis, you need to start steroids. If you’re pretty confident on viral or HSV, you can hold off. Give dexamethasome while you’re figuring it out.
Don’t delay antimicrobials for the CT or LP. CSF becomes sterilize after 6 hours after IV abx.
Do you CT before every LP? If AMS, focal neuro deficits, papilledema, new onset seizures, hx/o neuro dx or immunosuppression.
Get opening pressure if you can.
Normal CSF:< 50 protein, < 5 WBCs, no RBC, no organisms.
Bacterial Meningitis: < 2/3 glucose, > 50 protein, > 100 WBC, few RBCs, organism seen on 70% cases.
Viral Mengingitis: normal glucose, normal protein, > 10 WBC (lymphs), few RBCs, no organisms on gram stain.
Herpes encephalitis: > 2/3 serum glucose, < 50 or > 50 protein, > 100 WBC, > 10 RBC, no organisms on gram stain. Seen in elderly with headache/fever.
Two criteria: Reller Criteria (elevated CSF cell count >5, elevated CSF protein >50, immunocompromised (HIV or transplant), age <2yo) and Bouza Criteria (elevated CSF WBC count >10, immunocompromised (HIV or transplant), and age <2yo). If meet criteria, likely start acyclovir before getting back CSF PCR. Acyclovir can be nephrotoxic and increase seizure threshold. (PulmCrit, 2017)
If meningococcus, remember exposure prophylaxis.
Meningitis and Encephalitis, Michael Abraham, The Crashing Patient Conference 2015.