[21] Encephalitis Flashcards

1
Q

What is encephalitis?

A

Inflammation of the brain parenchyma associated with neurological dysfunction

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2
Q

How does encephalitis differ from meningitis?

A

Inflammation of the brain tissue vs inflammation of the meninges

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3
Q

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

A

~50%

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4
Q

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

A

Viruses

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5
Q

Other than viruses, what else can cause encephalitis?

A
  • Other organisms
  • Toxins
  • Autoimmune disorders
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6
Q

What are the two types of viral encephalitis?

A
  • Acute viral encephalitis

- Post-infectious encephalitis

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7
Q

What is acute viral encephalitis?

A

Direct viral infection of the brain

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8
Q

What is post-infectious encephalitis?

A

An autoimmune process that occurs following infection elsewhere in the body

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9
Q

What is the most common viral cause of encephalitis?

A

HSV

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10
Q

What other viruses can cause encephalitis?

A
  • CMV
  • Adenovirus
  • Influenza virus
  • Rabies
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11
Q

What are the bacterial causes of encephalitis?

A
  • TB
  • Mycoplasma
  • Listeria
  • Lyme disease
  • All causes of bacterial meningitis
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12
Q

What fungi can cause encephalitis?

A
  • Histoplasmosis

- Candidiasis

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13
Q

What parasites can cause encephalitis?

A
  • Toxoplasmosis

- Schistosomiasis

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14
Q

What are the risk factors for encephalitis?

A
  • Age <1
  • Age >65
  • Immunodeficiency
  • Travel to endemic locations
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15
Q

What is the clinical hallmark of acute encephalitis?

A

Triad of:

  • Fever
  • Headache
  • Altered mental status
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16
Q

What do most patients with viral encephalitis initially present with?

A

Symptoms of meningitis

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17
Q

What are the symptoms of meningitis?

A
  • Fever
  • Headache
  • Neck stiffness
  • Vomiting
18
Q

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

A
  • Altered consciousness
  • Convulsions
  • Focal neurological signs
  • Signs of raised ICP
  • Psychiatric symptoms
19
Q

What are the signs of raised ICP?

A
  • Severe headache
  • Vertigo
  • Nausea
  • Convulsions
  • Mental confusion
20
Q

At what point should patients be diagnosed with encephalitis?

A

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

21
Q

What investigations can be used to help identify encephalitis?

A
  • MRI brain scan
  • EEG
  • LP
  • Urinalysis
  • Bloods
22
Q

Why is an MRI useful in diagnosing encephalitis?

A

Can determine inflammation and differentiate other possible causes

23
Q

Why can EEG be used in diagnosing encephalitis?

A

Produces background slowing as an early sign of cerebral involvement

24
Q

Why is an EEG not very useful in diagnosing encephalitis?

A

Not very specific

25
Q

What test should be performed on LP?

A

PCR of CSF to detect viral DNA

26
Q

What are the potential differentials for encephalitis?

A
  • Aseptic meningitis
  • Toxic/metabolic encephalopathy
  • Malignant hypertension
  • Intracranial tumours and cysts
  • SLE
  • Intracranial bleed
  • Traumatic brain injury
  • Ischaemic strokes
  • Bacterial meningitis
27
Q

What should the initial management of encephalitis consist of?

A

Antiviral therapy and supportive management

28
Q

What antiviral should be given an immunocompetent host?

A

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

29
Q

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

A

That the causative agent is HSV

30
Q

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

A

Most cases are

31
Q

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

A

Combination therapy of ganciclovir, forscarnet and aciclovir

32
Q

What supportive care may be given in encephalitis?

A
  • Endotracheal intubation
  • Mechanical ventilation
  • Circulatory support
  • Prevention and management of secondary bacterial infection
  • DVT prophylaxis
  • GI prophylaxis
33
Q

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

A

Corticosteroids and mannitol

34
Q

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

A

Shunting or surgical decompression by craniotomy

35
Q

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

A

Impending uncal herniation

36
Q

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

A

So as not to aggravate cerebral oedema

37
Q

What additional treatments can be given in encephalitis?

A

Anti-convulsants and sedatives if needed

38
Q

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

A

Antibiotics

39
Q

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

A

Immune modulators

40
Q

What are the potential complications of encephalitis?

A
  • Inappropriate ADH secretion
  • DIC
  • Cardiac and respiratory arrest
  • Epilepsy
  • Neuropsychiatric impairment
  • Physical problems
41
Q

What neuropsychiatric impairment might occur as a result of encephalitis?

A
  • Changes in personality
  • Cognitive, behavioural or emotional impairment
  • Severe amnestic syndrome
42
Q

What physical problems may occur as a result of encephalitis?

A
  • Balance, coordination and dexterity problems
  • Speech and swallowing problems
  • Total dependency