What is the treatment approach for meningitis vs meningoencephalitis?

Treatment Approach for Meningitis vs Meningoencephalitis

Meningitis and meningoencephalitis require fundamentally different treatment approaches: bacterial meningitis demands immediate empiric antibiotics (vancomycin plus ceftriaxone) within 1 hour of presentation, while meningoencephalitis requires immediate empiric acyclovir in addition to antibacterial coverage due to the high likelihood of HSV encephalitis. 1

Initial Stabilization and Assessment (Both Conditions)

All patients require immediate stabilization of airway, breathing, and circulation as the first priority. 1

• Senior clinician review should occur within the first hour, with intensive care assessment for any patient with Glasgow Coma Scale ≤12 or National Early Warning Score ≥7 1
• Blood cultures must be obtained within 1 hour of hospital arrival 1
• Document Glasgow Coma Scale immediately for prognostic value and monitoring 1

Meningitis: Diagnostic and Treatment Algorithm

Timing of Lumbar Puncture and Antibiotics

For suspected bacterial meningitis without signs of shock or severe sepsis:

• Perform LP within 1 hour of arrival if safe to do so 1
• Start antibiotics immediately after LP, within the first hour 1
• If LP cannot be performed within 1 hour, give antibiotics immediately after blood cultures and perform LP as soon as possible (preferably within 4 hours of antibiotic initiation) 1

For patients with predominantly sepsis or rapidly evolving rash:

• Give antibiotics immediately after blood cultures—do not wait for LP 1
• Start fluid resuscitation with 500 mL crystalloid bolus 1
• Follow Surviving Sepsis guidelines 1
• Do not perform LP at this time 1

When to Delay LP for Neuroimaging

Obtain CT before LP only if: 1

• Focal neurological signs present
• Papilloedema identified
• Continuous or uncontrolled seizures
• Glasgow Coma Scale ≤12

Empiric Antibiotic Regimen for Bacterial Meningitis

Standard empiric therapy: Vancomycin plus ceftriaxone (or cefotaxime) 1

Ceftriaxone dosing: 2

• Adults: 2 grams IV every 12-24 hours (maximum 4 grams/day)
• Pediatric meningitis: 100 mg/kg initial dose (max 4 grams), then 100 mg/kg/day (max 4 grams/day) divided once daily or every 12 hours
• Neonates: Administer over 60 minutes to reduce bilirubin encephalopathy risk

Adjunctive Dexamethasone

Administer dexamethasone before or at the time of first antibiotic dose in both children and adults with suspected bacterial meningitis. 1, 3

Viral Meningitis Management

Once viral meningitis is confirmed, treatment is primarily supportive: 4

• Provide analgesia for headache and other symptoms 4
• Ensure adequate hydration (IV or oral fluids) 4
• Discontinue antibiotics once viral diagnosis confirmed 4
• Expedite hospital discharge 4

Important caveat: Despite theoretical benefits, there is no evidence supporting acyclovir or valacyclovir for HSV or VZV meningitis (without encephalitis) 4

Meningoencephalitis: Diagnostic and Treatment Algorithm

Critical Distinction from Meningitis

Meningoencephalitis involves brain parenchymal inflammation, manifesting with altered mental status, focal neurological deficits, or seizures—not just meningeal signs. 5, 6

Immediate Empiric Treatment

Start triple therapy immediately while awaiting diagnostics: 1, 7

1. Acyclovir 10 mg/kg IV every 8 hours for suspected HSV encephalitis 1
2. Vancomycin plus ceftriaxone for bacterial coverage 1
3. Consider adding coverage for rickettsial/ehrlichial infection based on epidemiology 1

This triple coverage approach is mandatory because HSV encephalitis is the most common cause of encephalitis and requires prompt treatment, while bacterial meningitis cannot be excluded initially. 1, 8

Diagnostic Workup Priorities

MRI is the imaging modality of choice (90% sensitivity vs 25% for CT) and should be obtained within 48 hours. 7

CSF analysis is critical, with PCR results ideally available within 24-48 hours: 1, 7

• Test for HSV-1, HSV-2, VZV, and enterovirus 4
• Bacterial cultures and Gram stain
• Consider fungal and TB testing based on risk factors

EEG should be obtained when: 7

• Distinguishing psychiatric versus organic causes in patients with mildly altered behavior
• Subtle motor or non-convulsive seizures suspected
• Status epilepticus suspected (including non-convulsive status in patients with fluctuating GCS off sedation) 1

Etiology-Specific Treatment Modifications

Once pathogen identified, adjust therapy: 7

• HSV encephalitis: Continue acyclovir (proven mortality benefit) 1, 8
• Bacterial meningitis: Continue appropriate antibiotics 1
• Toxoplasma gondii: Pyrimethamine plus sulfadiazine or clindamycin 7
• Cerebral malaria (Plasmodium falciparum): Quinine, quinidine, or artemether; exchange transfusion if ≥10% parasitemia 7
• ADEM: High-dose IV methylprednisolone (1 gram daily for 3-5 days); consider plasma exchange if poor response to steroids 1, 7

Management of Complications

Seizure management: 1

• Treat suspected or proven seizures early
• Use EEG monitoring for suspected status epilepticus
• Consider prophylactic anticonvulsants (though evidence for routine prophylaxis is limited) 6

Raised intracranial pressure management: 1

• Maintain mean arterial pressure ≥65 mmHg (individualize based on age and clinical scenario)
• Head elevation, avoid hyperthermia and hyponatremia
• Maintain normocarbia and normoglycemia
• Routine ICP monitoring is not recommended 1

Fluid management: 1

• Keep patients euvolemic to maintain normal hemodynamic parameters
• Fluid restriction to reduce cerebral edema is not recommended
• Use crystalloids as initial fluid of choice
• Consider albumin for persistent hypotensive shock
• Use norepinephrine as first-line vasopressor after euvolemia restored

Common Pitfalls to Avoid

Do not delay antibiotics for imaging or LP in unstable patients or those with rapidly evolving symptoms. Delayed antibiotic administration is associated with adverse outcomes when patients progress to high-risk clinical severity. 1

Do not assume viral meningitis without LP and CSF analysis. Clinical examination maneuvers (Kernig sign, Brudzinski sign) have variable sensitivity and specificity and cannot reliably differentiate bacterial from viral meningitis. 3

Do not withhold acyclovir in suspected encephalitis while awaiting HSV PCR results. HSV encephalitis has high morbidity and mortality without treatment, and early acyclovir administration improves outcomes. 1, 8

Do not use calcium-containing solutions with ceftriaxone in neonates or administer simultaneously via Y-site in any patient. This can cause fatal ceftriaxone-calcium precipitation. 2

Discharge Planning and Follow-up

All patients require assessment for rehabilitation needs before discharge, as sequelae may not be immediately apparent: 1, 7

• Viral meningitis: Up to one-third develop chronic headaches, plus fatigue, sleep disorders, and emotional difficulties 4
• Meningoencephalitis: Common sequelae include anxiety, depression, cognitive deficits, and functional disability in 15-25% of survivors 6
• Arrange staged return to work/studies initially 4
• Formulate specific outpatient follow-up and ongoing therapy plans at discharge meeting 7