Meningitis and Septicaemia

Question 1

Name the three protective coverings of the CNS.

Answer 1

Outwards to inwards:
Dura Mater
Arachnoid Mater
Pia Mater

Question 2

Describe the dura mater.

Answer 2

Outermost, thick, opaque, fibrous layer attached to inner table of the skull

Question 3

What is the name for the pia and arachnoid mater together?

Answer 3

Leptomeninges

Question 4

Where is CSF normally found?

Answer 4

Within the vascularized subarachnoid space (between the arachnoid and pia)

Question 5

What causes meningitis?

Answer 5

When the CSF becomes contaminated by infective agents, leading to inflammation of the meninges

Question 6

What do we call the disorder when the inflammation of the meninges extends to the underlying brain?

Answer 6

Meningoencephalitis.

Question 7

What does the histology of a normal subarachnoid space show?

Answer 7

Blood vessels and CSF 
Very hypocellular (not many cells present)

Question 8

Define meningitis.

Answer 8

Inflammation of the leptomeninges and intervening CSF within the subarachnoid space.
Usually caused by an infection
Acute or chronic

Question 9

Describe the classification system of meningitis.

Answer 9

Acute/pyogenic/bacterial/septic meningitis
Acute aseptic/viral meningitis
Chronic e.g. TB meningitis

Question 10

Name common causative organisms for meningitis in neonates.

Answer 10

GROUP B STREP
E coli
Listeria monocytogenes

Question 11

List common causative organisms of meningitis for those up to 10 years.

Answer 11

NEISSERIA MENINGITIDIS (MENINGOCOCCUS) 
Haemophilus influenzae

Question 12

List common causative organisms for meningitis in adolescents.

Answer 12

NEISSERIA MENINGITIDIS

Question 13

Name common causative organisms of meningitis in adults.

Answer 13

NEISSERIA MENINGITIDS 
STREPTOCOCCUS PNEUMONIAE (PNEUMOCOCCUS)

Question 14

Name common causative organisms for meningitis in older adults.

Answer 14

STREPTOCOCCUS PNEUMONIAE

Listeria monocytogenes

Question 15

What are the 3 main major issues caused by meningitis?

Answer 15

Increased intracranial pressure
Meningeal irritation (Meningism) 
Meningococcal Septicaemia

Question 16

What are the signs and symptoms of increased intracranial pressure?

Answer 16

Severe headache, papilloedema (check for it before performing a lumbar puncture), nausea and vomiting, confusion and eventually loss of consciousness.

Question 17

What are the signs and symptoms of meningeal irritation?

Answer 17

Neck stiffness, photophobia, positive Kernig’s/Brudzinski’s signs

Question 18

What are the signs and symptoms of meningococcal septicaemia?

Answer 18

Picture of shock (circulatory collapse), rash caused by DIC, multi-organ dysfunction/failure

Question 19

What are the gross findings of acute pyogenic/septic meningitis?

Answer 19

Brain shows congestion, swelling/oedema/ pus accumulation

Question 20

What are the histological findings of acute pyogenic/septic meningitis?

Answer 20

Subarachnoid space - congested blood vessel, expanded, heavily infiltrated by acute inflammatory cells (neutrophils)

Question 21

What type of inflammation does Mycobacterium Tuberculosis cause in TB Meningitis?

Answer 21

Granulomatous inflammation

Question 22

What causes a granulomatous inflammation?

Answer 22

Chronic inflammation caused by persistent activation of T cell mediated immune response by an organism that is difficult to eradicate.

Question 23

What is a granuloma?

Answer 23

Multiple collections of activated macrophages surrounded by T lymphocytes

Question 24

What type of hypersensitivity is a granuloma?

Answer 24

Type IV

Question 25

What does the TB granuloma show?

Answer 25

Giant cells (fusion of multiple macrophages) - Langerhans giant cells Epithelioid cells (activated macrophages) Necrosis in the centre - caseous necrosis T lymphocytes surrounding the epithelioid cells Healing is attempted by fibrosis surrounding the granuloma

Question 26

Name some gross findings of TB meningitis.

Answer 26

Small nodules throughout the meningeal surface

Question 27

What is the outcome of viral meningitis?

Answer 27

Recovery due to no gross changes seen in the brain.

Question 28

What is the outcome of bacterial meningitis?

Answer 28

Most people survive due to early diagnosis and antibiotic treatment If treatment is delayed, fibrosis of the inflammatory exudate in the subarachnoid space may lead to permanent neurological deficits.

Question 29

What are the outcomes if treatment is delayed in bacterial meningitis.

Answer 29

Fibrosis of inflammatory exudate in subarachnoid space: - fibrosis around cranial nerves = cranial nerve palsies - blockage of CSF flow = hydrocephalus - Inflammation of blood vessels and occlusion = brain infarcts - epilepsy

Question 30

Define septicaemia.

Answer 30

Presence of propagating bacteria and their toxins in the blood

Question 31

Describe the pathogenesis of septic shock.

Answer 31

Septicaemia results in endothelial cell activation. Complement activation which contributes to pro-inflammatory state that leads to endothelial cell activation. Activated endothelial cells express adhesion molecules, pro-coagulants & produce cytokines. Multi-organ dysfunction/failure

Question 32

What occurs due to activated endothelial cells?

Answer 32

Widespread thrombosis - DIC Increased vascular permeability Vasodilation of microcirculation all over the body = severe hypotension and shock due to decrease in peripheral resistance

Question 33

What is DIC?

Answer 33

Thrombo-haemorrhagic disorder | Excessive widespread coagulation and formation of thrombi in the microcirculation.

Question 34

What happens in DIC in order for it to be called consumption coagulopathy?

Answer 34

Consumption of platelets and clotting factors as a result of the widespread thrombotic process

Question 35

Ecchymoses

Answer 35

Result of DIC | Haemorrhagic spots larger than 1cm

Question 36

Purpura

Answer 36

Result of DIC | Spots less than 1 cm

Question 37

Petechiae

Answer 37

``` Result of DIC Pinpoint bleeds (less than 1mm) ```

Question 38

What happens to the adrenal glands in meningococcal septicaemia?

Answer 38

Adrenal gland is under stress in shock due to increased demand for corticosteroids and catecholamines. In Neisseria meningitidis, massive bilateral adrenal haemorrhage occurs Mostly related to vascular endothelial injury and DIC Adrenal glands are converted to sacs of blood

Question 39

What is the name given to the adrenal necrosis/haemorrhage in meningococcal septicaemia?

Answer 39

Waterhouse-Friderichsen Syndrome

Question 40

What happens to platelets and D-dimers in DIC?

Answer 40

Platelets decrease because they are consumed in forming clots D-dimers increase because they show the presence of an inappropriate blood clot.