25 Viral meningitis

Question 1

Differentiate between meningitis and encephalitis.

Answer 1

Meningitis: inflammation of meninges.
Encephalitis: inflammation of brain.

Question 2

Define aseptic meningitis.

Answer 2

Clinical meningitis with white cell count >5x10^6/L. Negative bacterial culture for CSF.

Question 3

Epidemiology of viral meningitis:

Answer 3

Neonates and 5 year olds.

Question 4

Aetiology of viral meningitis. (5)

Answer 4

Enteroviruses (leading) - echoviruses, cockasackie, parecho viruses
Herpes: VZV, HSV2>>HSV1.
Mumps.
HIV.
Unknown in 35%.

Question 5

How do viruses invade the CNS to cause meningitis?

Answer 5

Cerebral microvascular endothelial cells.
Choroid plexus epithelium.
Olfactory nerve.

Question 6

Clinical presentation of viral meningitis?

Presentation in neonates?

Answer 6

Fever. Headache. Neck stiffness. Photophobia. Possible viral prodrome.
Neonates: nuchal rigidity + bulging anterior fontanelle.

Question 7

What are the examination findings in viral meningitis?

Answer 7

Kernels sign: hip and knee at 90o, knee cannot be extended.
Brudzinski’s sign. Neck flexion causes hip and knee flexion.
Nuchal rigidity: resistance to neck flexion.

Question 8

What is a lumbar puncture used for in meningitis?

Why CT beforehand sometimes?

Answer 8

MC&S. Protein. Glucose (+blood glucose). Viral PCR.

CSF removal may cause herniation through foramen magnum.

Question 9

What are the CSF findings in viral meningitis?

Answer 9

Lymphocytic WCC .

Question 10

What is the treatment for viral meningitis?

Answer 10

IV antibiotics if bacterial risk.

Supportive therapy - analgesis and antipyretics.

Question 11

What is the most common cause of viral meningitis in the UK?

Extra symptoms with this cause? (5)

Answer 11

Enteroviruses.

Fever, vomiting, anorexia, rash, URT symptoms.

Question 12

What is mollaret’s meningitis?

Cause?

Answer 12

Recurrent aseptic meningitis.

Major cause is HSV2.

Question 13

When can meningitis occur in VZV infection?

Answer 13

During chickenpox, singles, on its own or after vaccination.

Question 14

What is the aetiology of enchepalitis? (10)

Answer 14

HSV1»>HSV2.
VZV, EBV, measles, mumps, enteroviruses.
Bacteria: strep pneumoniae, neisseria meningitidis, TB.
Acute disseminated encephalomyopathy.

Question 15

What is the clinical presentation of encephalitis? (5)

Answer 15

Altered mental state, fever, headache, meningism (may be absent).
± focal neurology: seizures, weakness, dysphasia, ataxia.

Question 16

Why are MRI and EEG used to investigate encephalitis.

Answer 16

MRI - changes in HSV encephalitis.

EEG: HSV encephalitis shows abnormal temporal lobe activity.

Question 17

What is the treatment for viral encephalitis?

Answer 17

High dose IV acyclovir on clinical suspicion for 14-21 days.

No oral switch recommended.

Question 18

What is the epidemiology of herpes simplex encephalitis?

Pathogenesis?

Answer 18

Bimodal - under 20 + over 50.

Reactivation in trigeminal ganglia -> acute focal necrotising encephalitis.

Question 19

What is the outcome of herpes simplex encephalitis?

Answer 19

30% mortality at 18months even if treated.

Survivors: paralysis, speech loss, personality change.

Question 20

What is acute disseminated encephalomyopathy?
CSF findings?
Rx?

Answer 20

Immune mediated CNS demyelination. May follow viral illness/vaccination. Clinical features of encephalitis.
CSF findings=viral meningitis.
Rx: steroids.