What is the initial management of suspected encephalitis?

Initial Management of Suspected Encephalitis

The initial management of suspected encephalitis requires immediate neurological specialist assessment, prompt lumbar puncture (LP) unless contraindicated, and empiric intravenous aciclovir therapy within 6 hours of admission. 1, 2

Immediate Assessment and Stabilization

• Patients with falling level of consciousness require urgent assessment by Intensive Care Unit staff for airway protection, ventilatory support, management of raised intracranial pressure, optimization of cerebral perfusion pressure, and correction of electrolyte imbalances 2, 1
• Patients should be managed in a setting where clinical neurological review can be obtained as soon as possible and definitely within 24 hours of referral 2, 1
• Children and young adults should be stabilized before performing any diagnostic procedures, and an anaesthetist, paediatrician or intensivist should be consulted 2

Diagnostic Approach

Lumbar Puncture

• All patients with suspected encephalitis should have an LP as soon as possible after hospital admission, unless there are specific contraindications 2
• Contraindications to immediate LP include:
  • Moderate to severe impairment of consciousness (GCS < 13) or fall in GCS of >2
  • Focal neurological signs
  • Papilledema
  • Seizures until stabilized
  • Coagulation abnormalities
  • Immunocompromise
  • Suspected raised intracranial pressure 2

Neuroimaging

• If there is a clinical contraindication indicating possible raised intracranial pressure, a CT scan should be performed as soon as possible 2
• An immediate LP following CT should be considered on a case-by-case basis, unless imaging reveals significant brain shift, tight basal cisterns, or an alternative diagnosis 2
• If an immediate CT is not indicated, imaging (preferably MRI) should be performed as soon as possible after the LP 2
• Unselected CT scanning of all patients before LP can cause unnecessary delays for the majority of patients without contraindications 2

Special Considerations for LP

• In anticoagulated patients, adequate reversal is mandatory before LP:
  • Protamine for those on heparin
  • Vitamin K, prothrombin complex concentrate, or fresh frozen plasma for those on warfarin 2
• In patients with bleeding disorders, replacement therapy is indicated 2
• If unclear how to proceed with coagulation issues, seek advice from a haematologist 2
• In situations where an LP is not possible initially, review the situation every 24 hours and perform LP when safe 2
• If an initial LP is non-diagnostic, a second LP should be performed 24-48 hours later 2

Empiric Treatment

• Intravenous aciclovir should be started if the initial CSF and/or imaging findings suggest viral encephalitis, and definitely within 6 hours of admission if results are awaited 2, 3
• If the first CSF microscopy or imaging is normal but clinical suspicion of HSV or VZV encephalitis remains, aciclovir should still be started within 6 hours 2
• Dosage for aciclovir in adults and adolescents (12 years and older): 10 mg/kg intravenously every 8 hours 4, 2
• Dosage for children (3 months to 12 years): 20 mg/kg intravenously every 8 hours 2, 4
• The dose should be adjusted in patients with renal impairment 2, 4
• Treatment duration for herpes simplex encephalitis is typically 10 days 4, 3

Additional Management Considerations

• Access to neuroimaging (MRI preferred over CT), neurophysiology (EEG), and CSF diagnostic assays is critical 2, 1
• CSF PCR results should ideally be available within 24-48 hours of LP 2, 1
• When a diagnosis is not rapidly established or a patient fails to improve with therapy, transfer to a neurological unit is recommended as soon as possible and definitely within 24 hours 2
• Patients should not be discharged without either a definite or suspected diagnosis, and arrangements for outpatient follow-up 1, 5

Common Pitfalls to Avoid

• Delaying aciclovir treatment while waiting for diagnostic confirmation can significantly worsen outcomes 3, 6
• Performing unnecessary CT scans before LP in patients without clinical contraindications delays diagnosis and treatment 2
• Failing to recognize encephalitis in elderly patients, who may present atypically and are at higher risk of HSV encephalitis 2, 7
• Neglecting to adjust aciclovir dosing in patients with renal impairment 2, 4
• Discharging patients without adequate follow-up planning, as many experience ongoing complications 1, 5