(neuro) cerebral inflammation

Question 1

define meningitis

Answer 1

inflammation of the meninges caused by a bacterial or viral infection

Question 2

define encephalitis

Answer 2

inflammation of the brain caused by infection or autoimmune mechanisms

Question 3

define cerebral vasculitis

Answer 3

inflammation of the blood vessel walls, involving the brain (alternatively called angiitis)

Question 4

which is more aggressive in terms of meningitis: a bacterial or viral infection?

Answer 4

bacterial infection of the meninges tends to be more aggressive than a viral one

Question 5

define myelitis

Answer 5

inflammation of the spinal cord

Question 6

what is an alternative term for cerebral vasculitis?

Answer 6

angiitis

Question 7

what is angiitis?

Answer 7

cerebral vasculitis (i.e. inflammation of the walls of small blood vessels)

Question 8

how was the existence of the blood-brain barrier discovered?

Answer 8

dyes/tracers were injected intravenously into various tissues

accumulated in most tissues, except CNS tissues

= suggested the existence of a BBB

Question 9

describe the vascularisation of the CNS

Answer 9

the CNS has very dense vascularisation as no neurone is more than 100 micrometres away from a capillary

Question 10

how dense is the vascularisation of the CNS?

Answer 10

very dense - no neurone is ever more than 100 micrometres away from a capillary

Question 11

how much of the cardiac output is directed towards the brain?

Answer 11

approximately 20%

Question 12

how is the blood-brain barrier formed?

Answer 12

capillaries of the BBB have very strong tight junctions between the endothelial cells = massively reducing the solute and fluid leak across the capillary wall

Question 13

why does the BBB actually work?

Answer 13

there are very strong tight junctions between the endothelial cells that massively reduce fluid and solute leakage across the capillary wall

Question 14

how does diffusion occur across the endothelial tight junctions of the BBB?

Answer 14

nothing can freely diffuse across as the tight junctions are extremely strong = massively reduce the solute and fluid leakage across the capillary wall

Question 15

which CNS cell is involved in maintaining the BBB?

Answer 15

astrocytes

Question 16

how does the ‘tightness’ of the BBB capillaries compare to peripheral capillaries?

Answer 16

solutes that would normally diffuse and be exchanged across peripheral capillaries cannot cross the BBB

= special transporters to control the influx and efflux of these solutes into/out of the CNS

Question 17

how is the brain adapted to overcome the additional ‘tightness’ caused by the BBB?

Answer 17

= special transporters to control the influx and efflux of these solutes into/out of the CNS (that cannot diffuse normally across the capillary wall)

Question 18

give one way in which the tightness of the BBB is an advantage

Answer 18

blood-borne infectious agents have reduced entry into the CNS tissue

Question 19

what are the initial symptoms of encephalitis?

Answer 19

initially

• pyrexia (high body temperature)
• headache
• flu-like symptoms

Question 20

what are the longer-term symptoms of encephalitis?

Answer 20

within hours, days, weeks

• confusion, disorientation
• seizures/fits
• changes in personality/behaviour
• difficulty speaking
• weakness/loss of movement
• loss of consciousness

Question 21

what is the most common cause of encephalitis?

Answer 21

viral infection (herpes simplex, measles, varicella - chickenpox, Rubella)

Question 22

which viruses commonly cause encephalitis?

Answer 22

herpes simplex, measles, varicella (chickenpox), Rubella

Question 23

what are the possible causes of encephalitis?

Answer 23

viral infection

mosquite/tick/insect bites

bacterial/fungal infection

trauma

autoimmune

Question 24

what are the treatments for encephalitis?

Answer 24

depend on underlying cause BUT

• antivirals
• steroids
• antibiotics/antifungals
• analgesics
• anticonvulsants
• ventilation

Question 25

why are anti-convulsants used as treatment for encephalitis?

Answer 25

prophylactic treatment for potential seizures

Question 26

what is multiple sclerosis?

Answer 26

autoimmune demyelinating disease of the CNS

Question 27

how does multiple sclerosis occur?

Answer 27

autoimmune antibodies are produced against the myelin that encases the neurones of the CNS = causing demyelination and subsequent neurodegeneration

Question 28

what are the types of multiple sclerosis?

Answer 28

relapsing-remitting (associated w inflammation) secondary progression

Question 29

what is the relapsing-remitting type of multiple sclerosis associated with?

Answer 29

inflammation (i.e. inflammatory demyelination)

Question 30

why is myelin important?

Answer 30

insulation of the neurones of the CNS and to enable saltatory conduction

Question 31

how does multiple sclerosis initially present?

Answer 31

initially presents with different neurological presentation each time

Question 32

how does axonal loss progress with multiple sclerosis?

Answer 32

progressively worsens as MS proceeds from being relapsing-remitting to continuous (secondary progression)

Question 33

what does axonal loss cause?

Answer 33

neurodegeneration

Question 34

how does the cellular pathology of multiple sclerosis progress?

Answer 34

inflammation demyelination axonal loss neurodegeneration

Question 35

why do the symptoms vary so much between MS patients?

Answer 35

vary because the amount and location of damage/demyelination to the CNS is different in each person w MS

Question 36

what causes the progression of disease in multiple sclerosis and why?

Answer 36

increased inflammation | leads to increased demyelination = increased neurodegeneration

Question 37

how many people does meningitis affect yearly?

Answer 37

approx 5 million worldwide

Question 38

what is the long-term impact of meningitis on individuals?

Answer 38

leaves 1 in 5 people with an impairment after the infection has been cleared

Question 39

what are the main causes of meningitis?

Answer 39

bacterial infection (meningococcal, pneumococcal, haemophilus influnzae type B, streptococcal) viral infection (very rarely life-threatening) fungal infection

Question 40

what are the main causes of bacterial meningitis?

Answer 40

meningococcal (most common cause of bacterial meningitis in the UK) penumococcal HiB (haemophilus influenzae type B) streptococcal (main cause in new born babies)

Question 41

what is the most common cause of bacterial meningitis in the UK?

Answer 41

meningococcal

Question 42

what is the most common cause of bacterial meningitis in the newborns?

Answer 42

streptococcal

Question 43

how is meningitis confirmed?

Answer 43

take a small sample of CSF and stain it to check for the presence of pathogens (LUMBAR PUNCTURE)

Question 44

how do desired fluid and solute molecules overcome the blood-brain barrier?

Answer 44

active transport mechanisms (transport pumps)

Question 45

what are multiple sclerosis relapses associated with?

Answer 45

inflammatory (demyelination) activity

Question 46

what do immune cell infiltrates contain in multiple sclerosis?

Answer 46

both T lymphocytes and B lymphocytes = perivascular immune cell infiltration (CD3 T-cells and CD20 B-cells)

Question 47

what happens when the blood-brain barrier is disrupted?

Answer 47

leakage of blood from the capillary into the cerebral tissue = astrocytes migrate to clean up and respond to the leakage

Question 48

what is the response to a blood-brain barrier disruption?

Answer 48

astrocytes migrate to clean up and respond to the leakage

Question 49

which cells respond to a blood-brain barrier disruption?

Answer 49

astrocytes

Question 50

what is astrogliosis?

Answer 50

when the astrocyte numbers increase significantly to repair damage to the CNS (i.e. when BBB is damaged due to trauma/infection)

Question 51

which cells make up the perivascular immune cell infiltrate in multiple sclerosis?

Answer 51

CD3 T cells CD20 B cells = activated and then migrate across the BBB capillary walls to cause inflammation & damage