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Information ⬇

Author: David Sprigings

Consider encephalitis in any febrile patient with headache, abnormal behaviour or reduced conscious level. These clinical features have a broad differential diagnosis (Table 69.1), which must be considered. As prompt treatment of herpes simplex encephalitis (Appendix 69.1) can minimize brain injury and improve outcomes, aciclovir should be given to all patients with possible encephalitis, until the results of diagnostic tests are known.

Priorities ⬆ ⬇

  1. Review the physiological observations and make a focused clinical assessment (Table 69.2).
  2. If you suspect encephalitis, start aciclovir 10 mg/kg 8-hourly IV. If meningism is present, or there are other reasons to suspect bacterial meningitis, take blood cultures and start appropriate antibiotic therapy (Chapter 68).
  3. Arrange CT, LP and other urgent investigations (Table 69.3). In high-resource countries, the ready availability of CT makes it reasonable to do CT before LP in every case. CT should definitely be done before LP if there are risk factors for an intracranial mass lesion, or signs of raised intracranial pressure:
    • Immunosuppression (e.g. HIV-AIDS, immunosuppressive therapy)
    • History of brain tumour or focal infection
    • Major seizures within one week of presentation
    • Papilloedema
    • Reduced conscious level (Glasgow Coma Scale score <13)
    • Focal neurological signs (not including cranial nerve palsies)

Further Management ⬆ ⬇

  1. Management is directed by the clinical picture, neuroimaging and CSF formula (see Tables 68.5 and 68.6).
  2. If viral encephalitis is probable or cannot be excluded, continue aciclovir and seek advice from an infectious diseases physician and neurologist.
  3. Supportive treatment of viral encephalitis includes:
    • Analgesia as required (e.g. paracetamol, NSAID or codeine).
    • Control of seizures (see Chapter 16).
    • Attention to fluid balance. Losses are increased due to fever. Aim for an intake of 2–3L/day, supplementing oral with IV normal saline if needed. Check electrolytes and creatinine, initially daily. Hyponatraemia may occur due to inappropriate ADH secretion.

Further Reading ⬆

Graus F, Titulaer MJ, Balu R (2016) A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol 4, 391–404.

Solomon T, Michael BD, Smith PE, et al. (2012) Management of suspected viral encephalitis in adults: The Association of British Neurologists and British Infection Association National guidelines. J Infect 64, 347–373. Open access. http://www.journalofinfection.com/article/S0163-4453(11)00563-9/pdf