Cerebral Inflammation Flashcards
What is meningitis?
inflammation of the meninges caused by viral or bacterial infection
What is encephalitis?
inflammation of the brain caused by infection or autoimmune mechanisms
What is cerebral vasculitis?
inflammation of blood vessel walls (sometimes called angiitis)
How was the Blood Brain Barrier discovered?
Discovered that dyes injected intravenously will accumulate in most tissues but no the brain
How do we know the brain is rich in blood supply?
Dense vascularisation of the brain - No neuron is more than 100µm from a capillary
How does the BBB reduce fluid leak?
BBB capillaries have extensive tight junctions at the endothelial cell-cell contacts, massively reducing solute and fluid leak across the capillary wall
What does the tightness of the BBB allow for?
solutes that can exchange across peripheral capillaries cannot cross the BBB
allows the BBB to control the exchange of these substances using specific membrane transporters to transport into and out of the CNS
Why is the BBB important?
Blood-borne infectious agents have reduced entry into CNS tissue
What happens when the endothelial layer of the BBB becomes disrupted after trauma?
Contents of the blood can move into brain
e.g. fibrinogen is seen in brain blood vessels after trauma
Glial cells react and astrocytes retract and break down BBB
Basement menbrane change and collagen builds up - possible sclerosis for vessels
What are initial symptoms of encephalitis?
Initially symptoms are flu-like with pyrexia (high body temperature) and headache
What are the subsequent symptoms of encephalitis?
confusion or disorientation seizures or fits changes in personality and behaviour difficulty speaking weakness or loss of movement loss of consciousness
What are the most common causes of encephalitis?
Viral infections
Herpes Simplex
Measles
Varicella (chickenpox)
Rubella (German measles)
What are other causes of encephalitis?
Mosquito, tick and other insect bites
Bacterial and fungal infections
Trauma
Autoimmune
How do we treat encephalitis?
Antivirals e.g. acyclovir Steroids Antibiotics/antifungals Analgesics Anti-convulsants Ventilation
What does treatment of encephalitis depend on?
The underlying cause
What is Multiple Sclerosis?
Autoimmune attach on the BBB
Demyelinating disease
Relapsing - remitting episodes (due to inflammatory activity)
Deficits increase over time due to axonal loss
What is the cellular pathology of MS?
Inflammation
Demyelination
Axonal loss
Neurodegeneration
Why do symptoms of MS vary so much?
Random disorder that can occur in the white matter anywhere in the brain
Amount and location of the damage varies so much
What is characteristic of inflammation in MS?
Perivascular cuffing - infiltration of immune cells into the substance of the brain
Form cuff around vessels
Largely T-cells but also B-cells
What are the main features of Meningitis?
Irritation, inflammation and swelling of the meninges
6th most common infectious disease killer
Affects more than 5 million people per annum worldwide
Leaves 1 in 5 of the infected people with an impairment
What are the causes of Meningitis?
Bacterial
Meningococcal – the most common cause of bacterial meningitis in UK
Pneumococcal
Haemophilus Influenzae type b (Hib)
Streptococccal – the main cause in newborn babies
What are the other causes of Meningitis?
Viral - very rarely life-threatening
Fungal
Who is more vulnerable to Meningitis?
Children
University students (people mixing with each other)
Eldery
Immunocompromised
What is an infection of the spinal cord known as?
Vertebral osteomyelitis
What are the symptoms of Meningitis?
high temperature cold hands and feet nausea + vomiting confusion breathing quickly muscle and joint pain pale, mottled or blotchy skin spots or a rash headache a stiff neck (nuchal rigidity) a dislike of bright lights being very sleepy or difficult to wake fits (seizures)
What diagnostic methods can diagnose meningitis?
Blood tests
Lumbar puncture
CT Scan
What methods can diagnose encephalitis?
CT Scan
MRI Scan
EEG
Lumbar punctures
What are the main complications with Meningitis?
hearing loss
visual impairments
problems with memory and concentration
cognitive decline
co-ordination, movement and balance problems
learning difficulties and behavioural problems
vision loss, which may be partial or total
loss of limbs – amputation is sometimes necessary to stop the infection
bone and joint problems, such as arthritis
kidney problems
How might someone with encephalitis present differently to someone with meningitis?
Behavioural changes
Seizures
How might someone with meningitis present differently to someone with encephalitis?
Neck stiffness
How do you tell if someone has had a seizure if you haven’t observed it?
EEG
Electroencephalogram
Measure electrical activity of brain
Tell you that normal brainwaves are interrupted by abnormal brain waves
Where is the epidural space found?
Spinal Cord
Where is the site of lumbar puncture?
Below L2 vertebrae
What does the lumbar puncture needle go through before reaching fluid?
Dura
Arachnoid
What does CSF look like normally?
Watery and clear
What is the significance of low glucose in CSF?
Confirm brain is infected
Low blood glucose is a hallmark of infection
What structures would look different in severe meningitis?
Large ventricles
due to blockage of aqueduct
(hydrocephalus)
What happens if you do a lumbar puncture in someone with raise intra-cranial pressure?
Herniation through foramen magnum
Must rule our raised intracranial pressure before lumbar puncture
