Encephalitis

Question 1

What is encephalitis?

Answer 1

Inflammation of the brain parenchyma associated with neurological dysfunction

Question 2

How does encephalitis differ from meningitis?

Answer 2

Inflammation of the brain tissue vs inflammation of the meninges

Question 3

In what percentage of cases of encephalitis is an aetiological agent identified?

Answer 3

~50%

Question 4

What is the most common type of causative organism of encephalitis?

Answer 4

Viruses

Question 5

Other than viruses, what else can cause encephalitis?

Answer 5

• Other organisms
• Toxins
• Autoimmune disorders

Question 6

What are the two types of viral encephalitis?

Answer 6

• Acute viral encephalitis

- Post-infectious encephalitis

Question 7

What is acute viral encephalitis?

Answer 7

Direct viral infection of the brain

Question 8

What is post-infectious encephalitis?

Answer 8

An autoimmune process that occurs following infection elsewhere in the body

Question 9

What is the most common viral cause of encephalitis?

Answer 9

HSV

Question 10

What other viruses can cause encephalitis?

Answer 10

• CMV
• Adenovirus
• Influenza virus
• Rabies

Question 11

What are the bacterial causes of encephalitis?

Answer 11

• TB
• Mycoplasma
• Listeria
• Lyme disease
• All causes of bacterial meningitis

Question 12

What fungi can cause encephalitis?

Answer 12

• Histoplasmosis

- Candidiasis

Question 13

What parasites can cause encephalitis?

Answer 13

• Toxoplasmosis

- Schistosomiasis

Question 14

What are the risk factors for encephalitis?

Answer 14

• Age <1
• Age >65
• Immunodeficiency
• Travel to endemic locations

Question 15

What is the clinical hallmark of acute encephalitis?

Answer 15

Triad of:

• Fever
• Headache
• Altered mental status

Question 16

What do most patients with viral encephalitis initially present with?

Answer 16

Symptoms of meningitis

Question 17

What are the symptoms of meningitis?

Answer 17

• Fever
• Headache
• Neck stiffness
• Vomiting

Question 18

What symptoms often follow the symptoms of meningitis in cases of viral encephalitis?

Answer 18

• Altered consciousness
• Convulsions
• Focal neurological signs
• Signs of raised ICP
• Psychiatric symptoms

Question 19

What are the signs of raised ICP?

Answer 19

• Severe headache
• Vertigo
• Nausea
• Convulsions
• Mental confusion

Question 20

At what point should patients be diagnosed with encephalitis?

Answer 20

When there is altered consciousness, lethargy or personality change for >24 hours with no other explainable cause

Question 21

What investigations can be used to help identify encephalitis?

Answer 21

• MRI brain scan
• EEG
• LP
• Urinalysis
• Bloods

Question 22

Why is an MRI useful in diagnosing encephalitis?

Answer 22

Can determine inflammation and differentiate other possible causes

Question 23

Why can EEG be used in diagnosing encephalitis?

Answer 23

Produces background slowing as an early sign of cerebral involvement

Question 24

Why is an EEG not very useful in diagnosing encephalitis?

Answer 24

Not very specific

Question 25

What test should be performed on LP?

Answer 25

PCR of CSF to detect viral DNA

Question 26

What are the potential differentials for encephalitis?

Answer 26

- Aseptic meningitis - Toxic/metabolic encephalopathy - Malignant hypertension - Intracranial tumours and cysts - SLE - Intracranial bleed - Traumatic brain injury - Ischaemic strokes - Bacterial meningitis

Question 27

What should the initial management of encephalitis consist of?

Answer 27

Antiviral therapy and supportive management

Question 28

What antiviral should be given an immunocompetent host?

Answer 28

IV aciclovir 10mg/kg every 8 hours for 10-21 days

Question 29

On what assumption is the administration of IV aciclovir in encephalitis made?

Answer 29

That the causative agent is HSV

Question 30

Why is it assumed the causative agent of the encephalitis is HSV?

Answer 30

Most cases are

Question 31

What antiviral therapy should be given to immunocompromised patients in encephalitis?

Answer 31

Combination therapy of ganciclovir, forscarnet and aciclovir

Question 32

What supportive care may be given in encephalitis?

Answer 32

- Endotracheal intubation - Mechanical ventilation - Circulatory support - Prevention and management of secondary bacterial infection - DVT prophylaxis - GI prophylaxis

Question 33

What medical management should be considered for patients with raised ICP due to encephalitis?

Answer 33

Corticosteroids and mannitol

Question 34

What surgical interventions can be considered if medical management of raised ICP in encephalitis fails?

Answer 34

Shunting or surgical decompression by craniotomy

Question 35

When specifically may surgical intervention be required in raised ICP due to encephalitis?

Answer 35

Impending uncal herniation

Question 36

Why do IV fluids need to be managed carefully in encephalitis?

Answer 36

So as not to aggravate cerebral oedema

Question 37

What additional treatments can be given in encephalitis?

Answer 37

Anti-convulsants and sedatives if needed

Question 38

What should be given instead of anti-virals if the cause of encephalitis is bacterial?

Answer 38

Antibiotics

Question 39

What should be given if the cause of encephalitis is post-infectious?

Answer 39

Immune modulators

Question 40

What are the potential complications of encephalitis?

Answer 40

- Inappropriate ADH secretion - DIC - Cardiac and respiratory arrest - Epilepsy - Neuropsychiatric impairment - Physical problems

Question 41

What neuropsychiatric impairment might occur as a result of encephalitis?

Answer 41

- Changes in personality - Cognitive, behavioural or emotional impairment - Severe amnestic syndrome

Question 42

What physical problems may occur as a result of encephalitis?

Answer 42

- Balance, coordination and dexterity problems - Speech and swallowing problems - Total dependency