Cerebral Inflammation and Disorders Flashcards
What is the definition of meningitis?
Inflammation of the meninges caused by viral or bacterial infection
What is the definition of encephalitis?
Inflammation of the brain caused by infection or autoimmune mechanisms
What is the definition of cerebral vasculitis?
Inflammation of blood vessel walls (angiitis)
What is the definition of myelitis?
Inflammation of the spinal cord
What causes the blood brain barrier?
- dense vascularisation of the CNS
What forms the blood brain barrier (BBB)?
extensive tight junctions at the endothelial cell-cell contacts, massively reducing the fluid leak across capillary walls
What does the BBB do?
control the exchange of the substances using specific membrane transporters to transport into and out of the CNS (influx and efflux transporters).
What is the site of problems in the blood brain barrier?
- Perivascular space
- promotes drainage of solutes in diseases such as Alzheimer’s
What happens in BBB disruption?
- endothelial layer disruption
- blood components leak into the brain (fibrinogen)
- astrocytes withdraw end feet from the vessel wall
- further compromising the BBB
- collagen buildup leading to hardening of the vessel wall
What are the initial symptoms of encephalitis?
- flu-like
- pyrexia (fever)
- headache
What are the subsequent symptoms of encephalitis?
- confusion
- seizures/fits
- personality/behaviour changes
- difficulty speaking
- weakness/loss of movement
- loss of consciousness
What are the causes of encephalitis?
MOST COMMON: - herpes simplex - measles - varicella - rubella OTHER: - insect bites - bacteria/fungal infections - trauma - autoimmune
How to treat encephalitis?
dependent on the cause, but may include:
- antivirals e.g. acyclovir
- steroids
- antibiotics/antifungals
- analgesics
- anti-convulsants
- ventilation
How does COVID-19 affect the brain?
- appears to cause acute inflammatory vasculitis
- doesn’t affect brain tissue
- either perivascular or vascular
- causes small haemorrhages
What is Multiple Sclerosis?
- autoimmune demyelinating disease of the CNS
- relapses linked to inflammatory activity
- progression is linked to neurodegeneration
- neurological deficit, relapses and remits but steadily progresses
What is the cellular pathology of MS?
- inflammation
- demyelination
- axonal loss
- neurodegeneration
How would you look for evidence of demyelination
MRI scan
Why do MS symptoms vary?
the amount and location of damage to the nervous system varies from person to person
What are the two courses of symptoms for MS?
- relapsing-remitting
- secondary progression
What inflammation is involved in MS?
perivascular immune cell infiltration
- CD3 T-cells
- CD20 B-cells
What are the causes of meningitis?
bacterial: - meningococcal (most common cause in the UK) - pneumococcal - haemophilus Influenza type B - streptococcal (new-born) other: - viral (rarely life threatening) - fungal
What is the pathophysiology of meningitis?
- pathogens from the nasopharynx or upper airways enter the CNS
- bateria release toxins causing neuronal damage and cell death
- the antigens/toxins trigger an immune response and immune cells damage nerves
- inflammatory cascade leads to cerebral oedema
- intracranial pressure rises
How do you confirm a diagnosis of meningitis?
CSF sample, lumbar puncture
How does antibiotics pass the BBB?
high dose, IV antibiotics does pass through the BBB
What is an infection of the spinal cord known as?
Myelitis
What types of infections tend to cause encephalitis?
Virus
What diagnostic tests can be performed to diagnose meningitis and encephalitis?
- physical examination
- lumbar puncture, with subsequent cultures + glucose test
- Brain scan (CT+MRI)
- bloods
- urine analysis
What are some of the long term effects of meningitis?
- seizures
- visual disturbances
- behavioural changes
- confusion
- amnesia
- excessive fatigue
- hearing loss (biggest cause in children)
- aphasia
- learning disabilities
- memory loss
- poor concentration
- clumisness/co-ordination problems
- headaches
- weakness
- speech problems
Which is more severe, bacterial or viral meningitis?
bacterial, 1 in 10 die from it
What are the hallmarks of encephalitis?
- seizures
- fever
- behaviour changes
- confusion and disorientation
- aphasia
- visual disturbances
Why is encephalitis more likely to be viral?
Because viruses are able to pass through the blood-brain barrier
What are the hallmark features of meningitis?
- sudden fever
- severe headache
- nausea/vomiting
- double vision
- drowsiness
- light sensitivity
- stiff neck
- distinctive rash
What would you treat meningitis with?
- broad spectrum antibiotics
- analgesia
- steroids
- anti-inflammatories
- anti-pyretics
What is the structure of the capillaries that make up the BBB? DELETE
- extensive tight junctions at the endothelial cell-cell contacts
- massively reduced solute and fluid leak across the capillary wall
Describe the vascularisation of the CNS in the BBB?
no neuron is more than 100 micrometers from a capillary
Why is the tight control of the BBB beneficial?
blood-borne infections have reduced entry to CNS tissue
What is the structure of the capillaries of the BBB?
- endothelial layer
- collagen layer
- astrocytes with end feet on vessel wall
What is an infection of both the spinal cord and brain known as?
encephalomyelitis
How can you tell the difference between meningitis and encephalitis?
Encephalitis has:
- photophobia
- seizures
- neurologic findings (weakness, aphasia, behviour change)
