Meningitis

Question 1

why is meningitis a medical emergency?

Answer 1

It can cause life-threatening septicaemia and result in permanent damage to the brain or nerves.

Question 2

What is meningitis?

Answer 2

an inflammatory process of leptomeninges and CSF (Meningoencephalitis refers to inflammation to meninges and brain parenchyma

Question 3

How can meningitis be classified?

Answer 3

a) Acute pyogenic : usually bacterial meningitis
b) Aseptic : usually viral meningitis or lymphocytic pleocytosis
c) Chronic : Mycobacterium tuberculosis (TBM)

Question 4

What are the ways in which infectious agents can enter the CNS?

Answer 4

Haematogenous spread : most common

Direct implantation - most often is traumatic but can be iatrogenic or congential

Local extension - secondary to established infections - most often from mastoid/frontal sinuses e.g. infected tooth etc

Viral agents usually enter along peripheral nerves e.g. rabies

Question 5

Acute bacterial meningitis - what are the different causative organisms depending on age groups?

Answer 5

<1 month = streptococcus agalactiae, E.coli and Listeria

1-23 months = Strep. pneumoniae, Neisseria meningitidis, e.coli, Haemophilus influenzae

2-50 years = Strep pneumoniae and N. meningitidis

> 50 years = Streptococcus pneumoniae,

N.meningitidis,
Listeria monocytogenes,
and
aerobic Gram negative bacilli

Question 6

what are the clinical features of meningitis?

Answer 6

Headache
Irritable
Neck stiffness
Photophobia
Fever
Vomiting
Varying levels of consciousness
Rash

(neonates, elderly and immunosuppressed have non specific presentation)

Question 7

what is the process of lab diagnosis in meningitis?

Answer 7

Blood cultures

Lumbar puncture : CSF for microscopy, Gram stain, culture & Biochemistry

EDTA blood for PCR

Question 8

CSF abnormalities in meningitis: normal compared to bacterial

Answer 8

Normal: clear, colourless with no protein or glucose

Bacterial: cloudy and turbid with high protein and low glucose and 100-2000 polymorphs

Question 9

Difference between bacterial and viral meningitis

Answer 9

Primarily affects children and young adults

Milder signs and symptoms
May start as respiratory or intestinal infection then viraemia

CSF shows raised lymphocyte count (50-200/cu mm); protein and sugar usually normal

Full recovery expected

Question 10

what causes viral meningitis?

Answer 10

Enteroviruses:
Echo, Coxsackie A ,B

Paramyxovirus:
Mumps
Herpes simplex, Varicella Zoster virus

Adenoviruses

Other:
Arboviruses, Lymphocytic choriomeningitis, HIV

Question 11

What is the epidemiology and aetiology of Tuberculous meningitis?

Answer 11

Higher incidence in immigrant populations (countries with a higher incidence of TB)

Insidious onset

Question 12

Nature of tuberculous meningitis - complications, CSF, protein and sugar content

Answer 12

High frequency of complications, cranial nerve palsies

CSF shows predominantly lymphocytic response but polymorphs also present

High protein, low/absent sugar

Question 13

what is recurrent meningitis?

Answer 13

> 2 episodes meningitis
Symptom-free intervals
Normal CSF between episodes
Must be differentiated from chronic meningitis