Neuro emergencies

Meningitis and encephalitis

Reviewed Nov 2026·3 references
New· views rounded down, updated weekly

Suspected bacterial meningitis: blood cultures, dexamethasone and antibiotics within 1 hour; do not delay for CT or LP. Add aciclovir for encephalitis. In India think also of TB meningitis, Japanese encephalitis, scrub typhus, cerebral malaria and cryptococcus.

At the bedside

Timed steps
  1. 1

    Cultures + treat

    0 min

    Blood cultures, then dexamethasone 10 mg IV with or just before ceftriaxone 2 g IV every 12 h (+ vancomycin if penicillin-resistant pneumococcus is a concern; + ampicillin 2 g every 4 h if > 50 years, pregnant, immunocompromised, alcohol use).

  2. 2

    Indications

    CT first only if

    Focal deficits (not cranial nerve), new seizures, GCS < 10, severe immunocompromise. Otherwise LP immediately. Never delay antibiotics for imaging.

  3. 3

    Aciclovir

    Encephalitis

    Altered behaviour, seizures, focal signs, fever: aciclovir 10 mg/kg IV every 8 h until HSV PCR negative (repeat if early and negative); MRI and EEG.

  4. 4

    Interpret

    CSF

    Bacterial: neutrophils, low glucose (CSF:serum < 0.4), high protein. TB: lymphocytes, very low glucose, high protein, ADA, GeneXpert. Viral: lymphocytes, normal glucose. Cryptococcus: India ink, CrAg.

  5. 5

    Add cover

    Tropical

    Scrub typhus (eschar, transaminitis): doxycycline or azithromycin. Malaria smear/RDT in every febrile coma. JE: supportive (no specific antiviral). TB meningitis: 4-drug ATT + dexamethasone.

  6. 6

    Support

    ICU

    Airway if GCS ≤ 8, seizure control, avoid hyponatraemia, ICP measures; dexamethasone 4 days (stop if not bacterial, or if Listeria).

Bacterial meningitis

Dexamethasone

IV
Dose
10 mg every 6 h for 4 days, first dose with or before antibiotic

Empirical meningitis

Ceftriaxone

IV
Dose
2 g every 12 h

HSV encephalitis

Aciclovir

IV over 1 h
Dose
10 mg/kg every 8 h for 14-21 days
Worked example
60 kg: 600 mg 8-hourly; reduce if creatinine clearance < 50 mL/min
Red flag · call your senior now
Petechial/purpuric rash with fever: meningococcaemia; antibiotics within minutes, shock management.
Red flag
Falling GCS, new focal signs or papilloedema: raised ICP or abscess; CT.
Pitfall
Waiting for CT before giving antibiotics.
Pitfall
Stopping aciclovir after a single negative PCR done within 72 h of symptom onset.
Pearl
Dexamethasone benefit is greatest in pneumococcal meningitis (de Gans 2002: mortality 7% vs 15%).

References

  1. 1

    van de Beek D, Cabellos C, Dzupova O, et al. ESCMID guideline: diagnosis and treatment of acute bacterial meningitis. Clin Microbiol Infect. 2016;22(Suppl 3):S37-S62

  2. 2

    de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. N Engl J Med. 2002;347(20):1549-1556

  3. 3

    Tunkel AR, Glaser CA, Bloch KC, et al. The management of encephalitis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2008;47(3):303-327

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