Cerebral inflammation & disorders

Question 1

what is meningitis?

Answer 1

inflammation of the meninges caused by viral or bacterial infection

Question 2

what is encephalitis?

Answer 2

inflammation of the brain caused by infection or autoimmune mechanisms

Question 3

what is cerebral vasculitis?

Answer 3

inflammation of blood vessel walls (sometimes called angiitis)

Question 4

What does meningitis histology look like?

Answer 4

Pus within subarachnoid space (indicating probable bacterial meningitis)
Proliferation of immune cells around blood vessels

Question 5

how vascularised is the brain?
Why is this necessary?

Answer 5

no neuron is more than 100micrometers from a capillary
Neuron is highly metabolically active, requires prolific local blood supply

Question 6

how does the BBB form?

Answer 6

BBB capillaries have extensive tight junctions at endothelial cell-cell contacts, massively reducing solute and fluid leak across capillary wall

Question 7

What does the tightness of the BBB enable?

Answer 7

Because of the “tightness” of the BBB capillaries, solutes that can exchange across peripheral capillaries cannot cross the BBB.

This allows the BBB to control the exchange of these substances using specific membrane transporters to transport into and out of the CNS (influx and efflux transporters).

Blood-borne infectious agents have reduced entry into CNS tissue.

Question 8

what happens if the BBB is broken?

Answer 8

endothelial cells are damaged, blood leaks into brain parenchyma including fibrinogen, astrocytes retract end feet (leaving BBB undefended), immune cells/ inflammatory cytokines can move into brain tissue

Question 9

what are the symptoms of encephalitis?

Answer 9

Initially symptoms are flu-like with pyrexia (high body temperature) and headache

Subsequently, within hours, days or weeks:
confusion or disorientation
seizures or fits
changes in personality and behaviour
difficulty speaking
weakness or loss of movement
loss of consciousness

Question 10

Causes of encephalitis?

Answer 10

In most cases, encephalitis is caused by viral infection, the commonest of which are:
Herpes Simplex
Measles
Varicella (chickenpox)
Rubella (German measles)

Other causes include:
Mosquito, tick and other insect bites
Bacterial and fungal infections
Trauma
Autoimmune

Question 11

how is encephalitis treated?

Answer 11

depends on underlying cause
antivirals (acyclovir)/antibiotics/antifungals
steroids
analgesics
anti-convulsants (often prophylactically)
ventilation

Question 12

what is multiple sclerosis?

Answer 12

demyelinating autoimmune disease of the CNS

Question 13

what is the cellular pathology of multiple sclerosis?

Answer 13

Inflammation

Demyelination

Axonal loss

Neurodegeneration

Question 14

What are the perivascular immune cells seen in infiltrates in MS?

Answer 14

CD3 T-cells and CD20 B-cells

Question 15

what are the bacterial causes of meningitis?

Answer 15

Meningococcal (Neisseria meningitidis) – the most common cause of bacterial meningitis in UK
Pneumococcal (streptococcus pneumoniae-most serious)
Haemophilus Influenzae type b (Hib)-reduced by Hib vaccination, previously a leading cause in children under 5
Streptococcal – the main cause in new-born babies

Question 16

what are the non- bacterial causes of meningitis?

Answer 16

viruses (rarely life threatening)
fungi

Question 17

What is myelitis? What is encephalomyelitis?

Answer 17

Infection of the spinal cord is known as myelitis. When both the brain and spinal cord are involved, the condition is known as encephalomyelitis.

Question 18

how is meningitis diagnosed?

Answer 18

lumbar puncture for CSF sample

Question 19

what are the hallmarks of meningitis?

Answer 19

sudden fever, severe headache, nausea or vomiting, double vision, drowsiness, sensitivity to bright light, and a stiff neck, rash (not always).

Question 20

Meningitis vs encephalitis

Answer 20

Question 21

what are some long term effects of meningitis?

Answer 21

Long term learning disabilities, memory loss, poor concentration, clumsiness/co-ordination problems, headaches, deafness/hearing problems/tinnitus/dizziness/loss of balance, epilepsy, weakness/paralysis/spasms, speech problems, visual problems.

Question 22

what diagnostic tests are useful for suspected encephalitis or meningitis?

Answer 22

Neurological examination, CT, MRI, lumbar puncture (CSF is usually clear and colourless; low glucose in bacterial meningitis; raised white blood cell counts are a sign of inflammation), blood, urine analysis.