Encephalitis

Question 1

Define encephalitis.

Answer 1

Encephalitis is defined as inflammation of the brain parenchyma associated with neurological dysfunction such as altered state of consciousness, seizures, personality changes, cranial nerve palsies, speech problems, and motor and sensory deficits.

Question 2

Explain the aetiology/risk factors of encephalitis.

Answer 2

Age <1 or >65 years
Immunodeficiency
Post-infection
Blood/body fluid exposure
Organ transplantation
Animal or insect bites
Location
Season
Swimming or diving in warm freshwater or nasal/sinus irrigation

Question 3

Summarise the epidemiology of encephalitis.

Answer 3

Around 2500 cases of encephalitis occur in England each year. Globally, the incidence of encephalitis is around 7 per 100,000 population per year.

Question 4

Recognise the presenting symptoms of encephalitis. Recognise the signs of encephalitis on physical examination.

Answer 4

Fever
Rash
Altered mental state
Focal neurological deficit
Meningismus
Parotitis
Lymphadenopathy
Optic neuritis
Acute flaccid paralysis
Movement disorder
Cough
Gastrointestinal infection
Seizures

Question 5

Identify appropriate investigations for encephalitis and interpret the results.

Answer 5

FBC
Peripheral blood smear
Serum electrolytes
Liver function tests
Blood cultures
Throat swab
Nasopharyngeal aspirate
Sputum culture
Chest radiography
CT brain
MRI brain
Electroencephalogram (EEG)
Cerebrospinal fluid (CSF) analysis, culture, serology and polymerase chain reaction (PCR)