What is the treatment for a suspected brain infection?

Treatment for Suspected Brain Infection

Immediately start intravenous aciclovir (10 mg/kg three times daily for adults; 500 mg/m² three times daily for children 3 months-12 years) within 6 hours of admission for any patient with suspected viral encephalitis, while simultaneously pursuing diagnostic workup including lumbar puncture and neuroimaging. 1

Immediate Critical Care Assessment

Patients with decreased level of consciousness require urgent ICU evaluation for:

• Airway protection and ventilatory support 1
• Management of raised intracranial pressure 1
• Optimization of cerebral perfusion pressure 1
• Correction of electrolyte imbalances 1

Empiric Antimicrobial Therapy

Start aciclovir empirically if:

• Initial CSF or imaging findings suggest viral encephalitis 1
• Clinical suspicion remains high even if initial CSF microscopy or imaging is normal 1
• There is potential delay in performing lumbar puncture 1

The evidence is compelling: Two randomized trials demonstrated that aciclovir reduces mortality in HSV encephalitis from 70% to less than 20-30%, with delays beyond 48 hours associated with worse outcomes. 1 Because HSV is the most commonly diagnosed viral encephalitis in industrialized countries and early treatment is critical for survival and reducing morbidity, empiric therapy should not be delayed. 1, 2

If bacterial meningitis is also suspected, add appropriate antibiotics per meningitis guidelines concurrently. 1

Diagnostic Workup (Performed Urgently, Not Delaying Treatment)

Neuroimaging:

• MRI is preferred; CT if MRI unavailable or patient too unstable 1
• Should be accessible under general anesthesia if needed 1
• Perform urgently to assess for cerebral edema, mass effect, and alternative diagnoses 1, 3

Lumbar puncture:

• Obtain CSF for PCR (HSV-1, HSV-2, VZV, enteroviruses), microscopy, culture, protein, glucose, and lactate 1
• CSF PCR results should be available within 24-48 hours 1
• CT before LP is only needed if: severe immunocompromise, focal neurological signs, papilledema, or significantly reduced consciousness level 1

Common pitfall: Unselected CT scanning of all patients before LP causes unnecessary delays (median 18.5 hours vs 6 hours for immediate LP), when most patients have no contraindications to immediate LP. 1

Specialist Consultation and Transfer

Obtain immediate neurological specialist opinion, with clinical review within 24 hours of referral. 1

Transfer to neurological/neuroscience unit if:

• Diagnosis not rapidly established 1
• Patient fails to improve with therapy 1
• Transfer should occur within 24 hours of being requested 1

Multidisciplinary care requires: neurologists, infectious disease physicians, virologists, microbiologists, neurophysiologists, neuroradiologists, neurosurgeons, and intensive care staff. 1

Duration of Aciclovir Treatment

For proven HSV encephalitis:

• Continue IV aciclovir for 14-21 days 1
• Perform repeat LP at 14-21 days to confirm CSF is HSV PCR-negative 1
• If CSF remains positive, continue IV aciclovir with weekly PCR until negative 1

Rationale: The original 10-day treatment regimen was associated with clinical relapses due to continuing viral replication in some cases, leading to the current recommendation for longer treatment duration. 1

For immunocompromised patients with HSV encephalitis:

• Treat for at least 21 days IV aciclovir 1
• Reassess with CSF PCR 1
• Consider long-term oral suppressive therapy until CD4 count >200×10⁶/L 1

Dose Adjustments

Reduce aciclovir dose in pre-existing renal impairment to prevent crystalluria and obstructive nephropathy, which can affect up to 20% of patients after 4 days of IV therapy. 1

Special Circumstances

For returning travelers from malaria-endemic areas:

• Obtain rapid blood malaria antigen tests and three thick/thin blood films 1
• If cerebral malaria likely and delay in results, start antimalarial treatment immediately 1

For immunocompromised patients, expand diagnostic workup to include:

• CSF PCR for EBV, CMV, HHV-6, HHV-7 1
• Mycobacterium tuberculosis culture 1
• Cryptococcal antigen testing 1
• Toxoplasma serology 1

Monitoring Environment

Patients require close monitoring in:

• Neurological wards, high dependency units, or intensive care units 1
• Quiet environment with frequent neurological assessments 1
• Routine isolation is not required 1

Discharge Planning

Do not discharge without definite or suspected diagnosis. 1

All patients require:

• Outpatient follow-up arrangements formulated at discharge meeting 1
• Access to rehabilitation assessment regardless of age 1
• Awareness that neuropsychiatric sequelae (anxiety, depression, behavioral changes) often emerge after discharge and may be more common than with other acute brain injuries 1

Critical consideration: 96% of encephalitis patients report ongoing complications, yet 33% were historically discharged without follow-up arrangements. 1