Viral meningoencephalitis

B00.4 + (G05.1*) / A86

DESCRIPTION

Patients present with headache, neck stiffness, and encephalitic symptoms which may include fever, personality or behavioural changes, hallucinations and seizures. Lumbar puncture typically shows mildly elevated protein, normal glucose and mild pleocytosis (< 500), mainly lymphocytes (early on polymorphs may predominate). Treatment for herpes simplex encephalitis should be commenced in all patients until this has been excluded (see below).

MEDICINE TREATMENT

Analgesia:

  • Paracetamol, oral, 1 g 4–6 hourly when required.
    • Maximum dose: 15 mg/kg/dose.
    • Maximum daily dose: 4 g in 24 hours.

AND/OR

  • NSAID, e.g.:
  • Ibuprofen, oral, 400 mg immediately then 8 hourly with meals, if needed.

LoEIII [61]

OR

  • Morphine, IV, to a total maximum dose of 10 mg (See Appendix II, for individual dosing and monitoring for response and toxicity).

Herpes simplex encephalitis

Clinical features are fever, change in behaviour and seizures, which may be either focal or generalised.

Evidence of mucocutaneous involvement is usually not present. Lumbar puncture shows the above features of viral meningoencephalitis. Evidence of encephalitis involving medial temporal lobe region on MRI/CT neuro-imaging or on EEG is strongly supportive of the diagnosis and positive HSV PCR test on CSF is diagnostic.

  • Aciclovir, IV, 10 mg/kg 8 hourly for 14 days (21 days in immunocompromised patients).
    • Start therapy as early as possible, i.e. before results are available.
    • A negative herpes PCR usually excludes the diagnosis unless the specimen was taken within 72 hours of onset of symptoms, when false negatives have been described.

Treat seizures appropriately, see Epilepsy.

LoEIII [62]

All suspected cases of herpes encephalitis should be discussed with a specialist.

REFERRAL

  • For neuro-imaging: patients not responding or worsening in condition, i.e. decrease in consciousness and cranial nerve palsies, despite appropriate therapy.
  • This is especially urgent in patients with tuberculous meningitis, who may develop hydrocephalus and require an urgent shunting procedure.
  • Patients with shunts.