6. Viruses of the CNS

Question 1

What is the difference between meningitis and encephalitis?

Answer 1

Meninges vs parenchyma inflamed

Encephalitis affects normal brain function and seizures predominate

Question 2

What are the viral causes of meningitis?

Answer 2

Enteroviruses
Mumps
Herpes: HHV6, VZV, HSV
Arboviruses

Question 3

What are the viral causes of encephalitis?

Answer 3

Herpes viruses
West Nile virus
Japanese encephalitis
Rabies

Question 4

What are the viral causes of post infectious encephalitis?

Answer 4

Measles

VZV

Question 5

What are the viral causes of neonatal brain infections?

Answer 5

Rubella
CMV
Zika virus

Question 6

How do viruses enter the CNS to cause meningitis?

Answer 6

Enteroviruses via bloodstream
Rabies and HSV along nerve pathways
Through olfactory mucosa

Question 7

What are the findings in CSF in a viral meningitis?

Answer 7

High protein, normal glucose
High lymphocytes
PCR only

Question 8

Apart from viruses, what can cause a raised lymphocyte count in CSF?

Answer 8

Spirochaetes, fungi, TB
Malignancy in the meninges
Connective tissue disease
Partial antibiotic treatment

Question 9

What is the treatment for viral meningitis?

Answer 9

Mild and self limiting:
rest, hydration and anti-pyretics
Seizures management
Consider antivirals in neonates

Question 10

How can viral meningitis be prevented?

Answer 10

MMR vaccine

Question 11

Which herpes virus most commonly causes encephalitis in neonates vs adults and children?

Answer 11

HSV 2 in neonates

HSV 1 in adults

Question 12

What part of the brain is affected in HSV encephalitis in neonates vs in adults?

Answer 12

Neonates: global, infection is disseminated beyond CNS
Adults: Temporal lobe, confined to CNS

Question 13

What are the clinical features of HSV encephalitis?

Answer 13

Acute neurological syndrome: behavioural disturbance, hemiparesis, aphasia, focal seizures

Question 14

How is HSV encephalitis diagnosed?

Answer 14

Temporal lobe changes on MRI
EEG
HSV PCR on CSF

Question 15

What is the treatment for HSV encephalitis?

Answer 15

IV aciclovir

Question 16

How is west nile virus transmitted?

Answer 16

Mosquito bites

Birds are also hosts: suspect a rise in cases if ‘bird falls’

Question 17

What are the clinical features of west nile virus?

Answer 17

80% no symptoms
Some mild flu-like illness
1% develop encephalitis or meningoencephalitis

Question 18

How is west nile virus diagnosed?

Answer 18

IgM on blood or CSF

PCR not useful as v short viraemic period

Question 19

What is the management of west nile virus?

Answer 19

Usually self limiting

Hospital support if severe

Question 20

What does the incubation period of rabies depend on?

Answer 20

Where the bite is eg. foot could take 12 weeks, face could take 3

Question 21

What are the clinical features of rabies?

Answer 21

Prodrome: fever, transient pain at bite, salivation

Restlessness, irritability, aggression, seizures

Question 22

How is rabies diagnosed?

Answer 22

History of a bite, travel
PCR on CSF or saliva
Biopsy from nape of neck for immunofluorescence
Serology only if never had vaccine or PEP

Question 23

What is the treatment for rabies?

Answer 23

Wash would ASAP

PEP within 10 days: Ig around bite and IM, rabies vaccine

Question 24

How is Japanese encephalitis acquired?

Answer 24

Infected mosquito

Mostly children infected or non-natives as adults acquire immunity

Question 25

What are the clinical features of Japanese encephalitis?

Answer 25

<1% get the disease

acute encephalitis or meningitis with acute flaccid paralysis

Question 26

How is japanese encephalitis diagnosed?

Answer 26

Clinical with a history of travel

IgM of blood and CSF

Question 27

How is japanese encephalitis prevented?

Answer 27

Avoid exposure to mosquitos

Immunisation

Question 28

What is spinal paralytic polio?

Answer 28

Asymmetric paralysis, usually in legs

-muscles supplied by efferent nerves from infected anterior horn cells

Question 29

What is bulbar polio?

Answer 29

Weakness of tongue and pharyngeal muscles

Question 30

What is post polio syndrome?

Answer 30

30-40 years after paralytic polio patient gets increased weakness and muscle pain
Due to loss of initially affected neurons

Question 31

What is the treatment of paralytic polio?

Answer 31

Supportive

Ventilation, monitor BP etc if bulbar involvement

Question 32

What diseases are caused by the Zika virus?

Answer 32

Congenital zika syndrome

Guillan-Barre syndrome

Question 33

What is Congenital zika syndrome?

Answer 33

Microcephaly

Partially collapsed skull, reduced brain tissue and brain damage

Question 34

What is the predominant feature of Guillan Barre syndrome?

Answer 34

Ascending paralysis

Question 35

What is SSPE?

Answer 35

Persistant measles in CNS years after infection causes behavioural and intellectual deterioration and seizures

Question 36

What is TSE?

Answer 36

Transmissable Spongiform Encephalopathy

Fatal degenerative brain disease caused by protein accumulations

Question 37

What are the types of TSE?

Answer 37

Sporadic/familial: inherited protein, older onset, rapid
Variant: ingestion of BSE containing products
Iatrogenic

Question 38

What are the clinical features of sporadic TSE?

Answer 38

Memory impairment, cognition and cerebellar ataxia

Late: dementia and ataxia

Question 39

What are the clinical features of variant TSE?

Answer 39

Behavioural or psych changes

Ataxia and involuntary movements

Question 40

How is TSE diagnosed?

Answer 40

MRI
CSF for 14-3-3 protein
Diagnosis can only be confirmed at autopsy

Question 41

What is seen at autopsy in TSE?

Answer 41

Spongiform changes
Amyloid plaques
Prion proteins

Question 42

How is TSE prevented?

Answer 42

Protect blood and food supply
Surgical equipment used on brain, spinal cord and posterior eye on a patient with CJD should not be reused
Low risk surgeries can be reused if autoclave used to decontaminate