Viral meningitis and encephalitis

Question 1

What is meningitis?

Answer 1

Inflammation of meninges

Question 2

What is encephalitis?

Answer 2

Inflammation of brain tissue

Question 3

What is meningoencephalitis?

Answer 3

I nflammation of meninges and brain tissue

Question 4

What is aseptic meningitis?

Answer 4

Clinical picture of meningitis observed (i.e. increased lymphocytes, increased protein, normal/reduced glucose)

BUT negative bacterial culture

Question 5

What is the main cause of aseptic meningitis?

Answer 5

Viruses mainly but also..

• listeria
• TB
• Syphilis (can not be grown in culture)

Question 6

What group of people is viral meningitis most common in?

Answer 6

Children/neonates

Question 7

What are the main viruses that cause viral meningitis?

Answer 7

1/3 cases = unknown
Enteroviruses e,g echovirus, coxsackie
- herpes viruses - HSV, EBV, VZV, cytomegalovirus
- Mumps virus
- HIV

• Measles
• Influenza/parainfluenza

Question 8

Which herpes simplex virus is more associated with meningitis?

Answer 8

HSV II

Question 9

What is the pathogenies of viral meningitis (i.e. how does it occur?)

Answer 9

Colonisation of mucosal surfaces

invasion of epithelial cells

Replication in cells

Dissemination and invasion in CNS - blood/nerves

Question 10

What are the clinical features of viral meningitis?

Answer 10

• Very similar to bacterial!
• Fever
• -/+ rash (unusual)
• ‘Meningism’ i.e. headache, neck stiffness, photophobia
• Sometimes viral prodrome i.e. evidence of previous viral infection

Question 11

What to look out for in infant viral meningitis?

Answer 11

Meningeal signs might be absent

• Nuchal rigidity (neck stiffness)
• Bulging anterior fontanelle (increasing intracranial pressure)

Question 12

what is the Kernigs sign?

Answer 12

With hips and knee flexed at 90 degrees, cannot extend knee due to pain/stiffness in hamstrings

Question 13

What is the Brudzinski’s sign?

Answer 13

Flexing the neck (pain) will cause the hips and knees to flex

Question 14

What is nuchal rigidity?

Answer 14

Resistance to flexion of neck

Question 15

What investigations should you perform?

Answer 15

Blood - FBC, U&E, CRP, clotting
CT scan (maybe)
Lumbar puncture 
     - Microscopy 
     - Glucose (CSF:Plasma)
     - Protein
     - PCR

Question 16

What is pleocytosis?

Answer 16

White blood cells in CSF

Question 17

What are the CSF features with viral meningitis?

Answer 17

• Lymphocytes in CSF approx 500 (polymorphs i..e neutrophils maybe in first 24hrs)
• Normal/reduced glucose (CSF:Plasma ratio; usually 50-66%)
• Increased protein (0.5-1.0; normal - 0.2-0.4)

Question 18

What is the treatment for viral meningitis?

Answer 18

Start appropriate IV antibiotics (risk of bacterial meningitis e.g. cefotoxime)

No evidence for use of antivirals (e.g. aciclovir) for viral meningitis - supportive therapy

Question 19

Which HSV, HSVI or II, is more commonly associated with meningitis?

Answer 19

HSVII (genital warts and meningitis) - meningitis can follow genital lesions

HSVI (cold sores and viral ENCEPHALITIS)

Question 20

What are the main cause of viral encephalitis?

Answer 20

Herpes simplex virus I and II (90% are HSV I)

VZV, CMV, EBV
Measles
Mumps
Enterovirus (inc polio)
HIV

Other causes - acute disseminated encephalomyopathy (ADEM)

Question 21

What are the clinical features of viral encephalitis?

Answer 21

Altered mental state (bizarre/abnormal behaviour) (Not in meningitis)

Fever
Headache
Meningism (may be absent)

+/- focal neurological symptoms
e.g. seizures**, weakness, dysphagia/asphasgia, CN palsy, ataxia

Question 22

What investigations should be performed for viral encephalitis?

Answer 22

• Blood tests
• CT BEFORE LP
• MRI - see changes typical of HSV
• Lumbar puncture - microscopy, protein, glucose, viral PCR

Question 23

What is the treatment for viral encephalitis?

Answer 23

Focused on HSV encephalitis

Aciclovir

Question 24

What is acute disseminated encephalomyelopathy? (ADEM)

Answer 24

Immune mediated CNS demyelination following viral illness or vaccination

CSF findings are same as viral meningitis